inetutils/doc/inetutils.texi

\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename inetutils.info
@settitle @sc{gnu} Inetutils
@c %**end of header

@include version.texi

@c Define new indices for file names and options.
@defcodeindex op
@defcodeindex fl

@c Put everything in one index (arbitrarily chosen to be the concept
@c index).
@syncodeindex fl cp
@syncodeindex fn cp
@syncodeindex ky cp
@syncodeindex op cp
@syncodeindex pg cp
@syncodeindex vr cp

@set Francois Fran@,{c}ois

@dircategory Basics
@direntry
* Inetutils: (inetutils).       GNU networking utilities.
* Common options: (inetutils)Common options.      Common options.
@end direntry

@dircategory Individual utilities
@direntry
* ftp: (inetutils)ftp invocation.                 FTP client.
* ftpd: (inetutils)ftpd invocation.               FTP Daemon.
* hostname: (inetutils)hostname invocation.       Show or set system host name.
* dnsdomainname: (inetutils)dnsdomainname invocation.       Show DNS domain name.
* inetd: (inetutils)inetd invocation.             Interner super-server.
* logger: (inetutils)logger invocation.           Send messages to the system log.
* ping: (inetutils)ping invocation.               Packets to network hosts.
* rcp: (inetutils)rcp invocation.                 Remote copy
* rexec: (inetutils)rexec invocation.             Remote execution client.
* rexecd: (inetutils)rexecd invocation.           Remote execution server.
* rlogin: (inetutils)rlogin invocation.           Remote login.
* rlogind: (inetutils)rlogind invocation.         Remote login server.
* rsh: (inetutils)rsh invocation.                 Remote shell.
* rshd: (inetutils)rshd invocation.               Remote shell server.
* syslogd: (inetutils)syslogd invocation.         Syslog server.
* talk: (inetutils)talk invocation.               Talk client.
* talkd: (inetutils)talkd invocation.             Talk server.
* telnet: (inetutils)telnet invocation.           User interface to TELNET.
* telnetd: (inetutils)telnetd invocation.         Telnet server.
* tftp: (inetutils)tftp invocation.               TFTP client.
* tftpd: (inetutils)tftpd invocation.             TFTP server.
* traceroute: (inetutils)traceroute invocation.   Trace the route to a host.
* uucpd: (inetutils)uucpd invocation.             Unix to Unix Copy.
* whois: (inetutils)whois invocation.             Whois user interface.
@end direntry

@copying
This manual documents version @value{VERSION} of the @sc{gnu} networking
utilities.

Copyright @copyright{} 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A
copy of the license is included in the section entitled ``GNU Free
Documentation License''.
@end quotation
@end copying

@titlepage
@title @sc{gnu} @code{inetutils}
@subtitle GNU networking utilities
@subtitle for version @value{VERSION}, @value{UPDATED}
@author Alain Magloire et al.

@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage
@shortcontents
@contents

@ifnottex
@node Top
@top GNU Inetutils

@insertcopying
@end ifnottex

@cindex networking utilities

@menu
* Introduction::                       Caveats, overview, and authors.
* Common options::                     Common options.

Diagnostic programs

* hostname invocation::                Show or set system host name.
* dnsdomainname invocation::           Show DNS domain name.
* logger invocation::                  Send messages to system log.
* ping invocation::                    Packets to network hosts.
* traceroute invocation::              Trace the route to a host.
* whois invocation::                   Whois user interface.

Clients

* ftp invocation::                     FTP client.
* tftp invocation::                    TFTP client.
* rsh invocation::                     Remote shell.
* rlogin invocation::                  Remote login.
* rexec invocation::                   Remote execution client.
* rcp invocation::                     Remote copy
* talk invocation::                    Talk client.
* telnet invocation::                  User interface to TELNET.

Daemons

* inetd invocation::                   Interner super-server.
* syslogd invocation::                 Syslog server.
* ftpd invocation::                    FTP Daemon.
* tftpd invocation::                   TFTP server.
* rshd invocation::                    Remote shell server.
* rlogind invocation::                 Remote login server.
* rexecd invocation::                  Remote execution server.
* talkd invocation::                   Talk server.
* telnetd invocation::                 Telnet server.
* uucpd invocation::                   Unix to Unix Copy.

* GNU Free Documentation License::     The license for this manual.
* Index::                              Index of manual.
@end menu

@c OK -- 2009-04-27
@node Introduction
@chapter Introduction
@cindex introduction

The GNU Network Utilities is a distribution of common networking
utilities and servers, including for example ping, traceroute and ftp.

This manual is a work in progress: many sections make no attempt to
explain basic concepts in a way suitable for novices.  Thus, if you
are interested, please get involved in improving this manual.  The
entire @sc{gnu} community will benefit.

@cindex bug, reporting
Please report bugs to @email{bug-inetutils@@gnu.org}.  Remember to
include the version number, machine architecture, input files, and any
other information needed to reproduce the bug: your input, what you
expected, what you got, and why it is wrong.  Diffs are welcome, but
please include a description of the problem as well, since this is
sometimes difficult to infer.

The individual utilities were originally derived from the 4.4BSDLite2
distribution, although some of them have more or less been rewritten.
What you are reading now is the authoritative and complete
documentation for these utilities; the man pages are now automatically
generated.

Many features were integrated from NetBSD, OpenBSD, FreeBSD and
GNU/Linux, the merges were done by a group of dedicated hackers (in no
particular order): Jeff Bailey, Marcus Brinkmann, Michael Vogt,
Bernhard Rosenkraenzer, Kaveh R. Ghazi, NIIBE Yutaka, Nathan
Neulinger, Jeff Smith, Dan Stromberg, David O'Shea, Frederic Goudal,
Gerald Combs, Joachim Gabler, Marco D'Itri, Sergey Poznyakoff, and
many more.

@node Common options
@chapter Common options

Certain options are available in all these programs.  Rather than
writing identical descriptions for each of the programs, they are
described here.  (In fact, every @sc{gnu} program accepts, or should
accept, these options.)

Many of these programs take arbitrary strings as arguments.  In those
cases, @option{--help} and @option{--version} are taken as these
options only if there is one and exactly one command line argument.

@table @option
@item --help
@opindex --help
@cindex help, online
Print a usage message, listing all available options, then exit
successfully.

@item --usage
@opindex --usage
@cindex usage, online
Print a condensed usage message, displaying all available options
formatted like a command line call, then exit successfully.

@item --version
@opindex --version
@cindex version number, finding
Print the version number, then exit successfully.

@item --
@opindex --
@cindex option delimiter
Delimit the option list.  Later arguments, if any, are treated as
operands even if they begin with @samp{-}.
@end table

@menu
* Exit status::                 Indicating program success or failure.
@end menu

@node Exit status
@section Exit status

@macro exitstatus
An exit status of zero indicates success, and a nonzero value
indicates failure.
@end macro

Nearly every command invocation yields an integral @dfn{exit status}
that can be used to change how other commands work.  For the vast
majority of commands, an exit status of zero indicates success.
Failure is indicated by a nonzero value --- typically @samp{1}, though
it may differ on unusual platforms, as POSIX requires only that it be
nonzero.

@node hostname invocation
@chapter @command{hostname}: Show or set system host name.
@cindex hostname

@command{hostname} is a program to show or set the name of host system.

@example
hostname [@var{option}@dots{}] [@var{name}]
@end example

@table @option
@item -a
@itemx --aliases
@opindex -a
@opindex --aliases
Get alias names.

@item -d
@itemx --domain
@opindex -d
@opindex --domain
Get DNS domain name.

@item -f
@itemx --fqdn
@itemx --long
@opindex -f
@opindex --fqdn
@opindex --long
Get DNS host name or Fully Qualified Domain Name.

@item -F
@itemx --file
@opindex -F
@opindex --file
Set host name or NIS domain name from FILE.

@item -i
@itemx --ip-addresses
@opindex -i
@opindex --ip-addresses
Get addresses for the host name.

@item -s
@itemx --short
@opindex -s
@opindex --short
Get short host name.

@item -y
@itemx --yp
@itemx --nis
@opindex -y
@opindex --yp
@opindex --nis
Get NIS/YP domain name.
@end table

@node dnsdomainname invocation
@chapter @command{dnsdomainname}: Show DNS domain name
@cindex dnsdomainname

@command{dnsdomainname} is a program to show the domain part of the
system's fully qualified domain name.  For example, if the FQDN of the
system is @code{name.example.org} the command will show
@code{example.org}.

The tool uses gethostname to get the host name of the system and
getaddrinfo to resolve it into a canonical name.  The part after the
first period (@code{.}) of the canonical name is shown.

The output is not necessarily related to the NIS/YP domain name.

@example
dnsdomainname [@var{option}@dots{}]
@end example

@node logger invocation
@chapter @command{logger}: Send messages to system log
@cindex logger

@command{logger} is a program to send entries to system log.  It
provides a shell command interface similar to the system log module.
@xref{Syslog, , Syslog, libc, The GNU C Library Reference Manual}, for
details.

@example
logger [@var{option}@dots{}] [@var{message}]
@end example

@table @option
@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Use IPv4 as transport when logging to a host.  The default behaviour
is to use whatever IP version that matches the host.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Use IPv6 as transport when logging to a host.  The option is present
also on systems without support for IPv6, but will then issue a warning
and then fall back to IPv4 when delivering the message.

Both options are most influencial when the target host is named using
a symbolic name, but numerical addresses for host or source must also
match if either of @option{--ipv4} or @option{--ipv6} is stated.

@item -i[@var{pid}]
@itemx --id=[@var{pid}]
@opindex -i
@opindex --id
Add process ID to each message.  If @var{pid} is not supplied, use the
process ID of the logger process with each line.  Notice, that
@var{pid} is an optional argument.  When supplied to the @option{-i}
option, it must follow the @samp{i} letter immediately, without any
separating whitespace.  When supplied to the @option{--id} form, it
must be separated from it by exactly one equals sign.

@item -h @var{host}
@itemx --host=@var{host}
@opindex -h
@opindex --host
Send messages to the given host or socket.  The @var{host} argument
can be either a local UNIX socket name (starting with a slash @samp{/}),
or:

@smallexample
@var{host}[:@var{port}]
@end smallexample

@noindent
where @var{host} is the remote host name or IP address, and the
optional @var{port} is a decimal port number or symbolic service
name from @file{/etc/services}.  If @var{port} is not specified,
the port number corresponding to the @samp{syslog} service is used.
If a numerical IPv6 address is given without a port specification,
then the address must be enclosed within brackets (like [::1]).

@item -u @var{socket}
@itemx --unix=@var{socket}
@opindex -h
@opindex --host
Send messages to the given local UNIX socket.  The @var{socket} argument
can be either an absolute path (starting with a slash @samp{/}), or a relative
path understood relative to the current working directory.

@item -S @var{addr}
@itemx --source=@var{addr}
@opindex -S
@opindex --source
Supply the source IP address for INET connections.  This option is
useful in conjunction with @option{--host} (see above).  The kind of
address specified here (IPv4 or IPv6) will propagate to influence
the resolution of the host address, if it is a symbolic name.

@item -s
@itemx --stderr
@opindex -s
@opindex --stderr
Log the message to standard error, as well as the system log.

@item -f @var{file}
@itemx --file=@var{file}
@opindex -f
@opindex --file
Log the content of the specified file.  If @var{file} is @samp{-} the
standard input is assumed.

@item -p @var{priority}
@itemx --priority=@var{priority}
@opindex -p
@opindex --priority
Enter the message with the specified priority.  The priority may be
specified numerically or as a @samp{facility.level} pair.  For
example, @option{-p local3.info} logs the message at the informational
level in the @samp{local3} facility.  The default is
@samp{user.notice}.

The actual list of supported facilities and levels is system specific.

@item -t @var{tag}
@itemx --tag=@var{tag}
@opindex -t
@opindex --tag
Mark every line in the log with the specified tag.
@end table

The options are followed by the message which should be written to the
log.  If not specified, and the @option{-f} flag is not provided,
standard input is logged.

The logger utility exits 0 on success, and >0 if an error occurs.

The following examples illustrate the usage of the @command{logger}
command:

@enumerate 1
@item Log the message @samp{System rebooted} to the local syslog.
Use default facility and priority:

@example
logger System rebooted
@end example

@item Run command and send its error output to the channel
@samp{local0.err}.  Mark each message with tag @samp{cmd}:

@example
command 2>&1 | logger -p local0.notice -t cmd
@end example

@item Log each line from file @file{warnings} to channel
@samp{daemon.warn} on host @samp{logger.runasimi.org},
using the source IP @samp{10.10.10.1}:

@example
logger -p daemon.warn -h logger.runasimi.org -S 10.10.10.1 --file
warnings
@end example
@end enumerate

@node ping invocation
@chapter @command{ping}: Packets to network hosts
@cindex ping

@c FIXME: The text is far to detailed about the actual implementation
@c of ping.  A user doesn't need to know that we are using TIMEVAL, or
@c how things are padded.

@command{ping} uses the ICMP protocol's mandatory @code{ECHO_REQUEST}
datagram to elicit an ICMP @code{ECHO_RESPONSE} from a host or
gateway.  @code{ECHO_REQUEST} datagrams (@dfn{pings}) have an IP and
ICMP header, followed by a @dfn{struct timeval} and then an arbitrary
number of @dfn{pad} bytes used to fill out the packet.  Synopsis:

@example
ping [@var{option}@dots{}] @var{host}@dots{}
@end example

@c Options controlling ICMP request types:
@c       --address              Send ICMP_ADDRESS packets (root only)
@c       --echo                 Send ICMP_ECHO packets (default)
@c       --mask                 Same as --address
@c       --timestamp            Send ICMP_TIMESTAMP packets
@c   -t, --type=TYPE            Send TYPE packets
@table @option
@item --address
@opindex --address
Send ICMP_ADDRESS packets, thus requesting the address netmask
being in use by the targetted host.

@item --echo
@opindex --echo
Send ICMP_ECHO requests (default).

@item --mask
@opindex --mask
Identical to @option{--address}.

@item --timestamp
@opindex --timestamp
Send ICMP_TIMESTAMP packets, thereby requesting a timed response
from the targetted host.  In successful cases three time values
will be returned.  All are expected to state the number of
milliseconds since midnight UTC.  The first, @samp{icmp_otime},
contains the original time for sending the request.  Then,
@samp{icmp_rtime}, is the time of reception by the target, and
finally, @samp{icmp_ttime}, is the time for transmitting an answer
back to the originator.

@item -t @var{type}
@itemx --type=@var{type}
@opindex --type
@opindex -t
Send @var{type} packets.  Accepted values are @samp{address},
@samp{echo}, @samp{mask}, and @samp{timestamp}.
@end table

@c Options valid for all request types:
@c   -c, --count=NUMBER         Stop after sending NUMBER packets
@c   -d, --debug                Set the SO_DEBUG option
@c   -i, --interval=NUMBER      Wait NUMBER seconds between sending each packet
@c   -n, --numeric              Do not resolve host addresses
@c   -r, --ignore-routing       Send directly to a host on an attached network
@c   -T, --tos=NUM              Set type-of-service to NUM
@c       --ttl=NUMBER           Set specified time-to-live on packet

@table @option
@item -c @var{n}
@itemx --count=@var{n}
@opindex -c
@opindex --count
Stop after sending (and receiving) @var{n} ECHO_RESPONSE packets.

@item -d
@itemx -debug
@opindex -d
@opindex --debug
Set the SO_DEBUG option on the socket being used.

@item -i @var{n}
@itemx --interval=@var{n}
@opindex -i
@opindex --interval
Wait @var{n} seconds between sending each packet.  The default is to
wait for one second between each packet.  This option is incompatible
with the @option{-f} option.

@item -n
@itemx --numeric
@opindex -n
@opindex --numeric
Numeric output only.  No attempt will be made to lookup symbolic names
for host addresses.

@item -r
@itemx --ignore-routing
@opindex -r
@opindex --ignore-routing-log
Bypass the normal routing tables and send directly to a host on an
attached network.  If the host is not on a directly-attached network,
an error is returned.  This option can be used to ping a local host
through an interface that has no route through it (e.g., after the
interface was dropped by @command{routed}).

@item -T @var{num}
@itemx --tos=@var{num}
@opindex -T
@opindex --tos
Set type-of-service, TOS, to NUM on transmitted packets.

@item --ttl=@var{n}
@opindex --ttl
Set the specified number @var{n} as value of time-to-live when
transmitting packets.  Acceptable values are 1 to 255, inclusive.
@end table

@c Options valid for --echo requests:
@c   -f, --flood                Flood ping (root only)
@c       --ip-timestamp=FLAG    Timestamp IP option of types tsonly,
@                               tsaddr, or (not yet implemented) prespec.
@c   -l, --preload=NUMBER       Send NUMBER packets as fast as possible before
@c                              falling into normal mode of behavior (root only)
@c   -p, --pattern=PATTERN      Fill ICMP packet with given pattern (hex)
@c   -R, --route                Record route IP option
@c   -s, --size=NUMBER          Send NUMBER data octets
@table @option
@item -f
@itemx --flood
@opindex -f
@opindex --flood
Flood ping.  Outputs packets as fast as they come back or one hundred
times per second, whichever is more.  For every ECHO_REQUEST sent a
period @samp{.} is printed, while for every ECHO_REPLY received a
backspace is printed.  This provides a rapid display of how many
packets are being dropped.  Only the super-user may use this option.
This can be very hard on a network and should be used with caution.

@item --ip-timestamp=@var{flag}
@opindex --ip-timestamp
Include IP option Timestamp in transmitted packets.  The value
@var{flag} is either of @samp{tsonly}, which only records up to nine
time stamps, and @samp{tsaddr}, which records IP addresses as well
as time stamps for at most four hosts.

@item -l @var{n}
@itemx --preload=@var{n}
@opindex -l
@opindex --preload
If @var{n} is specified, ping sends that many packets as fast as
possible before falling into its normal mode of behavior.

@item -p @var{pat}
@itemx --pattern=@var{pat}
@opindex -p
@opindex --pattern
You may specify up to 16 pad bytes to fill out the packet you send.
This is useful for diagnosing data-dependent problems in a network.
For example, @option{-p ff} will cause the sent packet to be filled
with all ones.

@item -R
@itemx --route
@opindex -R
@opindex --route
Record route.  Includes the @code{RECORD_ROUTE} field in the
ECHO_REQUEST packet and displays the route buffer on returned packets.
Note that the IP header is only large enough for nine such routes.
Many hosts ignore or discard this option.

@item -s @var{n}
@itemx --size=@var{n}
@opindex -s
@opindex --size
Specifies the number of data bytes to be sent.  The default is 56,
which translates into 64 ICMP data bytes when combined with the 8
bytes of ICMP header data.

@item -w @var{n}
@itemx --timeout=@var{n}
@opindex -w
@opindex --timeout
Stop after @var{n} seconds.

@item -W @var{n}
@itemx --linger=@var{n}
@opindex -W
@opindex --linger
Maximum number of seconds @var{n} to wait for a response.
@end table

@section Using ping for network fault isolation

When using @command{ping} for fault isolation, it should first be run
on the local host, to verify that the local network interface is up
and running.  Then, hosts and gateways further and further away should
be pinged.  Round-trip times and packet loss statistics are computed.
If duplicate packets are received, they are not included in the packet
loss calculation, although the round trip time of these packets is
used in calculating the minimum/average/maximum round-trip time
numbers.  When the specified number of packets have been sent (and
received) or if the program is terminated with a @samp{SIGINT}, a
brief summary is displayed.

This program is intended for use in network testing, measurement and
management.  Because of the load it can impose on the network, it is
unwise to use ping during normal operations or from automated scripts.

@ignore
@section ICMP Packet Details

An IP header without options is 20 bytes.  An ICMP ECHO_REQUEST packet
contains an additional 8 bytes worth of ICMP header followed by an
arbitrary amount of data.  When a packetsize is given, this indicated
the size of this extra piece of data (the default is 56).  Thus the
amount of data received inside of an IP packet of type ICMP ECHO_REPLY
will always be 8 bytes more than the requested data space (the ICMP
header).

If the data space is at least eight bytes large, ping uses the first
eight bytes of this space to include a timestamp which it uses in the
computation of round trip times.  If less than eight bytes of pad are
specified, no round trip times are given.
@end ignore

@section Duplicate And Damaged Packets

Ping will report duplicate and damaged packets.  Duplicate packets
should never occur, and seem to be caused by inappropriate link-level
retransmissions.  Duplicates may occur in many situations and are
rarely (if ever) a good sign, although the presence of low levels of
duplicates may not always be cause for alarm.

Damaged packets are obviously serious cause for alarm and often
indicate broken hardware somewhere in the ping packet's path (in the
network or in the hosts).

@section Trying Different Data Patterns

The (inter)network layer should never treat packets differently
depending on the data contained in the data portion.  Unfortunately,
data-dependent problems have been known to sneak into networks and
remain undetected for long periods of time.  In many cases the
particular pattern that will have problems is something that doesn't
have sufficient ``transitions'', such as all ones or all zeros, or a
pattern right at the edge, such as almost all zeros.  It isn't
necessarily enough to specify a data pattern of all zeros (for
example) on the command line because the pattern that is of interest
is at the data link level, and the relationship between what you type
and what the controllers transmit can be complicated.

This means that if you have a data-dependent problem you will probably
have to do a lot of testing to find it.  If you are lucky, you may
manage to find a file that either can't be sent across your network or
that takes much longer to transfer than other similar length files.
You can then examine this file for repeated patterns that you can test
using the @option{-p} option of ping.

@section TTL Details

The TTL, Time To Live value of an IP packet represents the maximum
number of IP routers that the packet can go through before being
thrown away.  In current practice you can expect each router in the
Internet to decrement the TTL field by exactly one.

The TCP/IP specification states that the TTL field for TCP packets
should be set to 60, but many systems use smaller values (4.3 BSD uses
30, 4.2 used 15).

The maximum possible value of this field is 255, and most UNIX systems
set the TTL field of ICMP (@code{ECHO_REQUEST}) packets to 255.  This
is why you will find you can ping some hosts, but not reach them with
@command{telnet} or @command{ftp}.

In normal operation @command{ping} prints the TTL value from the
packet it receives.  When a remote system receives a ICMP packet, it
can do one of three things with the TTL field in its response:

@table @bullet
@item
Not change it; this is what Berkeley UNIX systems did before the
4.3BSD-Tahoe release.  In this case the TTL value in the received
packet will be 255 minus the number of routers in the round-trip path.

@item
Set it to 255; this is what current Berkeley UNIX systems do.  In this
case the @code{TTL} value in the received packet will be 255 minus the
number of routers in the path from the remote system to the pinging
host.

@item
Set it to some other value.  Some machines use the same value for ICMP
packets that they use for TCP packets, for example either 30 or 60.
Others may use completely wild values.

@end table

Many hosts and gateways ignore the @code{RECORD_ROUTE} field, since
the maximum IP header length is far to small to hold all the routes.
There's not much that can be done about this.

Flood pinging is not recommended in general, and flood pinging the
broadcast address should only be done under very controlled
conditions.

@node traceroute invocation
@chapter @command{traceroute}: Trace the route to a host
@pindex traceroute

@command{traceroute} traces the route packets take to a host.
Synopsis:

@example
traceroute [@var{option}@dots{}] @var{host}
@end example

@table @option
@item -M @var{method}
@itemx --type=@var{method}
@opindex -M
@opindex --type
Use @var{method} (@samp{icmp} or @samp{udp}) for traceroute
operations.

@item -p @var{port}
@itemx --port=@var{port}
@opindex -p
@opindex --port
Use destination @var{port} (default: 33434).

@item -q @var{num}
@itemx --tries=@var{num}
@opindex -q
@opindex --tries
Send @var{num} probe packets per hop (default: 3).

@item --resolve-hostnames
@opindex --resolve-hostnames
Resolve hostnames.

@item -t @var{num}
@itemx --tos=@var{num}
@opindex -t
@opindex --tos
Set type-of-service, TOS, to NUM on transmitted packets.
@end table

@node whois invocation
@chapter @command{whois}: Whois user interface

Synopsis:

@example
whois [@var{OPTION}]... @var{OBJECT}...
@end example

@table @option
@item -a
Search all databases.

@item -F
Fast raw output (implies -r).

@item -g SOURCE:FIRST-LAST
Find updates from SOURCE from serial FIRST to LAST.

@item -h HOST
Connect to server HOST.

@item -H
Hide legal disclaimers.

@item -i ATTR[,ATTR]...
Do an inverse lookup for specified attributes.

@item -l
One level less specific lookup (RPSL only).

@item -L
Find all Less specific matches.

@item -M
Find all More specific matches.

@item -m
Find first level more specific matches.

@item -r
Turn off recursive lookups.

@item -p PORT
Connect to PORT.

@item -R
Force to show local copy of the domain object even if it contains
referral.

@item -S
Tell server to leave out syntactic sugar.

@item -s SOURCE[,SOURCE]...
Search the database from SOURCE.

@item -T TYPE[,TYPE]...
Only look for objects of TYPE.

@item -q [version|sources]
Query specified server info (RPSL only).

@item -t TYPE
Requests template for object of TYPE ('all' for a list).

@item -v TYPE
Requests verbose template for object of TYPE.

@item -x
Exact match only (RPSL only).
@end table

@node ftp invocation
@chapter @command{ftp}: FTP client
@cindex ftp

@command{ftp} is the user interface for FTP, File Transfer Protocol.
The program allows a user to transfer files to and from a remote
network site.  Synopsis:

@example
ftp [@var{option}@dots{}] [@var{host} [@var{port}]]
@end example

@table @option
@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Initially set addressing to IPv4 only.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Initially set addressing to IPv6 only.

@item -A
@itemx --active
@opindex -A
@opindex --active
Enable active mode transfer.

@item -p
@itemx --passive
@opindex -p
@opindex --passive
Enable passive mode transfer.

@item -d
@itemx --debug
@opindex -d
@opindex --debug
Enables debugging.

@item -g
@itemx --no-glob
@opindex -g
@opindex --no-glob
Disables file name globbing.

@item -i
@itemx --no-prompt
@opindex -i
@opindex --no-prompt
Turns off interactive prompting during multiple file transfers.

@item -n
@itemx --no-login
@opindex -n
@opindex --no-login
Restrains @command{ftp} from attempting @dfn{auto-login} upon initial
connection.  If auto-login is enabled, @command{ftp} will check the
@file{.netrc} (@pxref{The .netrc File}) file in the user's home
directory for an entry describing an account on the remote machine.
If no entry exists, @command{ftp} will prompt for the remote machine
login name (default is the user identity on the local machine), and,
if necessary, prompt for a password and an account with which to
login.

@itemx --prompt[=@var{prompt}]
@opindex --prompt
Print a command-line prompt, even if not on a tty.  If @var{prompt} is
supplied, its value is used instead of the default @samp{ftp> }.
Notice, that the argument is optional.

@item -t
@item --trace
@opindex -t
@opindex --trace
Enable packet tracing.
@end table

@menu
* Commands::
* Aborting A File Transfer::
* File Naming Conventions::
* File Transfer Parameters::
* The .netrc File::
@end menu

@node Commands
@section Commands

The client host with which @command{ftp} is to communicate may be
specified on the command line.  If this is done, @command{ftp} will
immediately attempt to establish a connection to an FTP server on that
host; otherwise, it will enter its command interpreter and await
instructions from the user.  When @command{ftp} is awaiting commands
from the user the prompt @samp{ftp>} is provided to the user.  The
following commands are recognized by @command{ftp}:

@table @code
@item ! [@var{command} [@var{args}]]
Invoke an interactive shell on the local machine.  If there are
arguments, the first is taken to be a command to execute directly,
with the rest of the arguments as its arguments.

@item $ @var{macro-name} [@var{args}]
Execute the macro @var{macro-name} that was defined with the macdef
command.  Arguments are passed to the macro unglobbed.

@item account [@var{passwd}]
Supply a supplemental password required by a remote system for access
to resources once a login has been successfully completed.  If no
argument is included, the user will be prompted for an account
password in a non-echoing input mode.

@item append @var{local-file} [@var{remote-file}]
Append a local file to a file on the remote machine.  If
@var{remote-file} is left unspecified, the local file name is used in
naming the remote file after being altered by any @code{ntrans} or
@code{nmap} setting.  File transfer uses the current settings for
type, format, mode, and structure.

@item ascii
Set the file transfer type to network ASCII.  This is the default
type.

@item bell
Arrange that a bell be sounded after each file transfer command is
completed.

@item binary
Set the file transfer type to support binary image transfer.

@item bye
@itemx quit
Terminate the FTP session with the remote server and exit
@command{ftp}.  An end of file will also terminate the session and
exit.

@item case
Toggle remote computer file name case mapping during @code{mget}
commands.  When case is on (default is off), remote computer file
names with all letters in upper case are written in the local
directory with the letters mapped to lower case.

@item cd @var{remote-directory}
Change the working directory on the remote machine to
remote-directory.

@item cdup
Change the remote machine working directory to the parent of the
current remote machine working directory.

@item chmod @var{mode} @var{file-name}
Change the permission modes of the file @var{file-name} on the remote
sytem to @var{mode}.

@item close
@itemx disconnect
Terminate the FTP session with the remote server, and return to the
command interpreter.  Any defined macros are erased.

@item cr
Toggle carriage return stripping during ASCII type file retrieval.
Records are denoted by a carriage return/linefeed sequence during
ASCII type file transfer.  When @code{cr} is on (the default),
carriage returns are stripped from this sequence to conform with the
UNIX single linefeed record delimiter.  Records on non-UNIX remote
systems may contain single linefeeds; when an ASCII type transfer is
made, these linefeeds may be distinguished from a record delimiter
only when cr is off.

@item delete @var{remote-file}
Delete the file @var{remote-file} on the remote machine.

@item debug [@var{debug-value}]
Toggle debugging mode.  If an optional @var{debug-value} is specified
it is used to set the debugging level.  When debugging is on,
@command{ftp} prints each command sent to the remote machine, preceded
by the string @samp{-->}.

@item dir [@var{remote-directory}] [@var{local-file}]
Print a listing of the directory contents in the directory,
@var{remote-directory}, and, optionally, placing the output in
@var{local-file}.  If interactive prompting is on, @command{ftp} will
prompt the user to verify that the last argument is indeed the target
local file for receiving dir output.  If no directory is specified,
the current working directory on the remote machine is used.  If no
local file is specified, or @var{local-file} is @samp{-}, output comes
to the terminal.

@item epsv4
Toggle the use of EPSV/EPRT for IPv4 addressing.  Default is off.

@item form @var{format}
Set the file transfer form to @var{format}.  The default format is
@samp{file}.

@c FIXME: List all avaiable FORMATS's.

@item get @var{remote-file} [@var{local-file}]
@itemx recv @var{remote-file} [@var{local-file}]
Retrieve the @var{remote-file} and store it on the local machine.  If
the local file name is not specified, it is given the same name it has
on the remote machine, subject to alteration by the current
@code{case}, @code{ntrans}, and @code{nmap} settings.  The current
settings for type, form, mode, and structure are used while
transferring the file.

@item glob
Toggle filename expansion for @code{mdelete}, @code{mget} and
@code{mput}.  If globbing is turned off with @code{glob}, the file
name arguments are taken literally and not expanded.  Globbing for
@code{mput} is done as in @command{csh}.  For @code{mdelete} and
@code{mget}, each remote file name is expanded separately on the
remote machine and the lists are not merged.  Expansion of a directory
name is likely to be different from expansion of the name of an
ordinary file: the exact result depends on the foreign operating
system and FTP server, and can be previewed by doing @code{mls
remote-files -}.

Note: @code{mget} and @code{mput} are not meant to transfer entire
directory subtrees of files.  That can be done by transferring a
@command{tar} archive of the subtree (in binary mode).

@item hash [@var{size}]
Toggle hash-sign (@samp{#}) printing for each data block transferred.
The size of a data block can optionally be specified.  If not given,
it defaults to 1024 bytes.

@item help [@var{command}]
@itemx ? [@var{command}]
Print an informative message about the meaning of command.  If no
argument is given, @command{ftp} prints a list of the known commands.

@item idle [@var{seconds}]
Set the inactivity timer on the remote server to @var{seconds}
seconds.  If seconds is omitted, the current inactivity timer is
printed.

@item ipv4
Select IPv4 as the only addressing scheme.

@item ipv6
Select IPv6 as the only addressing scheme.

@item ipany
Allow IPv4 as well as IPv6 addressing.

@item lcd [@var{directory}]
Change the working directory on the local machine.  If no directory is
specified, the user's home directory is used.

@item ls [@var{remote-directory}] [@var{local-file}]
Print a listing of the contents of a directory on the remote machine.
The listing includes any system-dependent information that the server
chooses to include; for example, most UNIX systems will produce output
from the command @command{ls -l}. If @var{remote}-directory is left
unspecified, the current working directory is used.  If interactive
prompting is on, @command{ftp} will prompt the user to verify that the
last argument is indeed the target local file for receiving ls output.
If no local file is specified, or if @var{local-file} is @samp{-}, the
output is sent to the terminal.

@item macdef @var{macro-name}
Define a macro called @var{macro-name}, with subsequent lines as the
macro definition; a null line (consecutive newline characters in a
file or carriage returns from the terminal) terminates macro input
mode.  There is a limit of 16 macros and 4096 total characters in all
defined macros.  Macros remain defined until a close command is
executed.  The macro processor interprets @samp{$} and @samp{\} as
special characters.  A @samp{$} followed by a number (or numbers) is
replaced by the corresponding argument on the macro invocation command
line.  A @samp{$} followed by an @samp{i} signals that macro processor
that the executing macro is to be looped.  On the first pass @samp{$i}
is replaced by the first argument on the macro invocation command
line, on the second pass it is replaced by the second argument, and so
on.  A @samp{\} followed by any character is replaced by that
character.  Use the @samp{\} to prevent special treatment of the
@samp{$}.

@item mdelete [@var{remote-files}]
Delete the remote-files on the remote machine.

@item mdir @var{remote-files} @var{local-file}
Like @code{dir}, except multiple remote files may be specified.  If
interactive prompting is on, @command{ftp} will prompt the user to
verify that the last argument is indeed the target local file for
receiving @code{mdir} output.

@item mget @var{remote-files}
Expand the @var{remote-files} on the remote machine and do a get for
each file name thus produced.  Resulting file names will then be
processed according to @code{case}, @code{ntrans}, and @code{nmap}
settings.  Files are transferred into the local working directory,
which can be changed with @code{lcd directory}; new local directories
can be created with @code{! mkdir directory}.

@item mkdir @var{directory-name}
Make a directory on the remote machine.

@item mls @var{remote-files} @var{local-file}
Like @code{nlist}, except multiple remote files may be specified, and
the @var{local-file} must be specified.  If interactive prompting is
on, @command{ftp} will prompt the user to verify that the last
argument is indeed the target local file for receiving @code{mls}
output.

@item mode [@var{mode-name}]
Set the file transfer mode to @var{mode-name}.  The default mode is
@samp{stream}.

@item modtime @var{file-name}
Show the last modification time of the file on the remote machine.

@item mput @var{local-files}
Expand wild cards in the list of local files given as arguments and do
a put for each file in the resulting list.  Resulting file names will
then be processed according to @code{ntrans} and @code{nmap} settings.

@item newer @var{file-name}
Get the file only if the modification time of the remote file is more
recent that the file on the current system.  If the file does not
exist on the current system, the remote file is considered newer.
Otherwise, this command is identical to get.

@item nlist [@var{remote-directory}] [@var{local-file}]
Print a list of the files in a directory on the remote machine.  If
@var{remote-directory} is left unspecified, the current working
directory is used.  If interactive prompting is on, @command{ftp} will
prompt the user to verify that the last argument is indeed the target
local file for receiving nlist output.  If no local file is specified,
or if @var{local-file} is @samp{-}, the output is sent to the
terminal.

@item nmap [@var{inpattern} @var{outpattern}]
Set or unset the filename mapping mechanism.  If no arguments are
specified, the filename mapping mechanism is unset.  If arguments are
specified, remote filenames are mapped during @code{mput} commands and
@code{put} commands issued without a specified remote target filename.
If arguments are specified, local filenames are mapped during
@code{mget} commands and @code{get} commands issued without a
specified local target filename.  This command is useful when
connecting to a non-UNIX remote computer with different file naming
conventions or practices.

The mapping follows the pattern set by @var{inpattern} and
@var{outpattern}.  The template @var{inpattern} is used for incoming
filenames (which may have already been processed according to the
@code{ntrans} and case settings).  Variable templating is accomplished
by including the sequences @samp{$1}, @samp{$2}, @dots{}, @samp{$9} in
@var{inpattern}.  Use @samp{\} to prevent this special treatment of
the @samp{$} character.  All other characters are treated literally,
and are used to determine the @code{nmap} @var{inpattern} variable
values.

For example, given inpattern @samp{$1.$2} and the remote file name
@file{mydata.data}, @samp{$1} would have the value @samp{mydata}, and
@samp{$2} would have the value @samp{data}.  The @var{outpattern}
determines the resulting mapped filename.  The sequences @samp{$1},
@samp{$2}, @dots{}., @samp{$9} are replaced by any value resulting
from the @var{inpattern} template.  The sequence @samp{$0} is replaced
by the original filename.  Additionally, the sequence
@samp{[@var{seq1}, @var{seq2}]} is replaced by @var{seq1} if
@var{seq1} is not a null string; otherwise it is replaced by
@var{seq2}.  For example, the command

@example
nmap $1.$2.$3 [$1,$2].[$2,file]
@end example

would yield the output filename @file{myfile.data} for input filenames
@file{myfile.data} and @file{myfile.data.old}, @file{myfile.file} for
the input filename @file{myfile}, and @file{myfile.myfile} for the
input filename @file{.myfile}.

Spaces may be included in @var{outpattern}, as in the example:
@code{nmap $1 sed "s/ *$//" > $1}.  Use the @samp{\} character to
prevent special treatment of the @samp{$}, @samp{[}, @samp{]}, and
@samp{,} characters.

@item ntrans [@var{inchars} [@var{outchars}]]
Set or unset the filename character translation mechanism.  If no
arguments are specified, the filename character translation mechanism
is unset.  If arguments are specified, characters in remote filenames
are translated during @code{mput} commands and @code{put} commands
issued without a specified remote target filename.  If arguments are
specified, characters in local filenames are translated during
@code{mget} commands and @code{get} commands issued without a
specified local target filename.  This command is useful when
connecting to a non-UNIX remote computer with different file naming
conventions or practices.

Characters in a filename matching a character in @var{inchars} are
replaced with the corresponding character in @var{outchars}.  If the
character's position in @var{inchars} is longer than the length of
@var{outchars}, the character is deleted from the file name.

@item open @var{host} [@var{port}]
Establish a connection to the specified host FTP server.  An optional
port number may be supplied, in which case, @command{ftp} will attempt
to contact an FTP server at that port.  If the @code{autologin} option
is on (default), @command{ftp} will also attempt to automatically log
the user in to the FTP server.

@item passive
Toggle passive mode.  If passive mode is turned on (default is off),
the @command{ftp} client will send a @code{PASV} command for all data
connections instead of the usual @code{PORT} command.  The @code{PASV}
command requests that the remote server open a port for the data
connection and return the address of that port.  The remote server
listens on that port and the client connects to it.  When using the
more traditional @code{PORT} command, the client listens on a port and
sends that address to the remote server, who connects back to it.
Passive mode is useful when using @command{ftp} through a gateway
router or host that controls the directionality of traffic.  (Note
that though @command{ftp} servers are required to support the
@code{PASV} command by RFC 1123, some do not.)  If @command{epsv4}
has been set to on, the client will attempt @code{EPSV} before
@code{PASV} for IPv4.  As a last resort @code{LPSV} is attempted.
With IPv6 only @code{EPSV} and @code{LPSV} are possible.

@item prompt
Toggle interactive prompting.  Interactive prompting occurs during
multiple file transfers to allow the user to selectively retrieve or
store files.  If prompting is turned off (default is on), any
@code{mget} or @code{mput} will transfer all files, and any
@code{mdelete} will delete all files.

@item proxy @var{ftp-command}
Execute an @command{ftp} command on a secondary control connection.
This command allows simultaneous connection to two remote FTP servers
for transferring files between the two servers.  The first proxy
command should be an open, to establish the secondary control
connection.  Enter the command @code{proxy ?} to see other ftp
commands executable on the secondary connection.  The following
commands behave differently when prefaced by @code{proxy}: @code{open}
will not define new macros during the auto-login process, @code{close}
will not erase existing macro definitions, @code{get} and @code{mget}
transfer files from the host on the primary control connection to the
host on the secondary control connection, and @code{put}, @code{mput},
and @code{append} transfer files from the host on the secondary
control connection to the host on the primary control connection.
Third party file transfers depend upon support of the FTP protocol
@code{PASV} command by the server on the secondary control connection.

@item put @var{local-file} [@var{remote-file}]
@itemx send @var{local-file} [@var{remote-file}]
Store a local file on the remote machine.  If @var{remote-file} is
left unspecified, the local file name is used after processing
according to any @code{ntrans} or @code{nmap} settings in naming the
remote file.  File transfer uses the current settings for type,
format, mode, and structure.

@item pwd
Print the name of the current working directory on the remote machine.

@item quote @var{arg}@dots{}
The arguments specified are sent, verbatim, to the remote FTP server.

@item reget @var{remote-file} [@var{local-file}]
@code{Reget} acts like @code{get}, except that if @var{local-file}
exists and is smaller than @var{remote-file}, @var{local-file} is
presumed to be a partially transferred copy of @var{remote-file} and
the transfer is continued from the apparent point of failure.  This
command is useful when transferring very large files over networks
that are prone to dropping connections.

@item remotehelp [@var{command-name}]
Request help from the remote FTP server.  If a command-name is
specified it is supplied to the server as well.

@item remotestatus [@var{file-name}]
With no arguments, show status of remote machine.  If filename is
specified, show status of @var{file-name} on remote machine.

@item rename [@var{from}] [@var{to}]
Rename the file from on the remote machine, to the file to.

@item reset
Clear reply queue.  This command re-synchronizes command/reply
sequencing with the remote FTP server.  Resynchronization may be
necessary following a violation of the FTP protocol by the remote
server.

@item restart @var{marker}
Restart the immediately following @code{get} or @code{put} at the
indicated marker.  On UNIX systems, marker is usually a byte offset
into the file.

@item rmdir @var{directory-name}
Delete a directory on the remote machine.

@item runique
Toggle storing of files on the local system with unique filenames.  If
a file already exists with a name equal to the target local filename
for a @code{get} or @code{mget} command, a @samp{.1} is appended to
the name.  If the resulting name matches another existing file, a
@samp{.2} is appended to the original name.  If this process continues
up to @samp{.99}, an error message is printed, and the transfer does
not take place.  The generated unique filename will be reported.  Note
that @code{runique} will not affect local files generated from a shell
command.  The default value is off.

@item sendport
Toggle the use of @code{PORT} commands.  By default, @command{ftp}
will attempt to use a @code{PORT} command when establishing a
connection for each data transfer.  The use of @code{PORT} commands
can prevent delays when performing multiple file transfers.  If the
@code{PORT} command fails, @command{ftp} will use the default data
port.  When the use of @code{PORT} commands is disabled, no attempt
will be made to use @code{PORT} commands for each data transfer.  This
is useful for certain FTP implementations which do ignore @code{PORT}
commands but, incorrectly, indicate they've been accepted.

@item site @var{arg}@dots{}
The arguments specified are sent, verbatim, to the remote FTP server
as a @code{SITE} command.

@item size @var{file-name}
Return size of @var{file-name} on remote machine.

@item status
Show the current status of @command{ftp}.

@item struct [@var{struct-name}]
Set the file transfer structure to @var{struct-name}.  By default
@samp{stream} structure is used.

@item sunique
Toggle storing of files on remote machine under unique file names.
Remote FTP server must support FTP protocol @code{STOU} command for
successful completion.  The remote server will report unique name.
Default value is off.

@item system
Show the type of operating system running on the remote machine.

@item tenex
Set the file transfer type to that needed to talk to TENEX machines.

@item trace
Toggle packet tracing.

@item type [@var{type-name}]
Set the file transfer type to @var{type-name}.  If no type is
specified, the current type is printed.  The default type is network
ASCII.

@item umask [@var{newmask}]
Set the default umask on the remote server to @var{newmask}.  If
@var{newmask} is omitted, the current umask is printed.

@item user @var{user-name} [@var{password}] [@var{account}]
Identify yourself to the remote FTP server.  If the password is not
specified and the server requires it, @command{ftp} will prompt the
user for it (after disabling local echo).  If an account field is not
specified, and the FTP server requires it, the user will be prompted
for it.  If an account field is specified, an account command will be
relayed to the remote server after the login sequence is completed if
the remote server did not require it for logging in.  Unless
@command{ftp} is invoked with @code{auto-login} disabled, this process
is done automatically on initial connection to the FTP server.

@item verbose
Toggle verbose mode.  In verbose mode, all responses from the FTP
server are displayed to the user.  In addition, if verbose is on, when
a file transfer completes, statistics regarding the efficiency of the
transfer are reported.  By default, verbose is on.
@end table

Command arguments which have embedded spaces may be quoted with quote
@samp{"} marks.

@node Aborting A File Transfer
@section Aborting A File Transfer

To abort a file transfer, use the terminal interrupt key (usually
@kbd{C-c}).  Sending transfers will be immediately halted.  Receiving
transfers will be halted by sending a FTP protocol ABOR command to the
remote server, and discarding any further data received.  The speed at
which this is accomplished depends upon the remote server's support
for @code{ABOR} processing.  If the remote server does not support the
@code{ABOR} command, an @samp{ftp>} prompt will not appear until the
remote server has completed sending the requested file.

The terminal interrupt key sequence will be ignored when @command{ftp}
has completed any local processing and is awaiting a reply from the
remote server.  A long delay in this mode may result from the
@code{ABOR} processing described above, or from unexpected behavior by
the remote server, including violations of the FTP protocol.  If the
delay results from unexpected remote server behavior, the local
@command{ftp} program must be killed by hand.

@node File Naming Conventions
@section File Naming Conventions

Files specified as arguments to @command{ftp} commands are processed
according to the following rules.

@enumerate
@item
If the file name @samp{-} is specified, standard input (for reading)
or standard output (for writing) is used.

@item
If the first character of the file name is @samp{|}, the remainder of
the argument is interpreted as a shell command.  @command{ftp} then
forks a shell, using @code{popen} with the argument supplied, and
reads/writes from standard input/output.  If the shell command
includes spaces, the argument must be quoted; e.g.  @samp{"ls -lt"}.
A particularly useful example of this mechanism is @samp{dir more}.

@item
Failing the above checks, if @dfn{globbing} is enabled, local file
names are expanded according to the rules used in the @command{csh};
c.f.  the @code{glob} command.  If the @command{ftp} command expects a
single local file (e.g.  @code{put}), only the first filename
generated by the globbing operation is used.

@item
For @code{mget} commands and @code{get} commands with unspecified
local file names, the local filename is the remote filename, which may
be altered by a @code{case}, @code{ntrans}, or @code{nmap} setting.
The resulting filename may then be altered if @code{runique} is on.

@item
For @code{mput} commands and @code{put} commands with unspecified
remote file names, the remote filename is the local filename, which
may be altered by a @code{ntrans} or @code{nmap} setting.  The
resulting filename may then be altered by the remote server if
@code{sunique} is on.
@end enumerate

@node File Transfer Parameters
@section File Transfer Parameters

The FTP specification specifies many parameters which may affect a
file transfer.  The type may be one of @samp{ascii}, @samp{image}
(binary), @samp{ebcdic}, and @samp{local} byte size (for PDP-10's and
PDP-20's mostly).  @command{ftp} supports the @samp{ascii} and
@samp{image} types of file transfer, plus local byte size 8 for tenex
mode transfers.

@command{ftp} supports only the default values for the remaining file
transfer parameters: @code{mode}, @code{form}, and @code{struct}.

@node The .netrc File
@section The @file{.netrc} File

The @code{.netrc} file contains login and initialization information
used by the auto-login process.  It resides in the user's home
directory.  The following tokens are recognized; they may be separated
by spaces, tabs, or new-lines:

@table @samp
@item machine name
Identify a remote machine name.  The auto-login process searches the
@file{.netrc} file for a machine token that matches the remote machine
specified on the @command{ftp} command line or as an open command
argument.  Once a match is made, the subsequent @file{.netrc} tokens
are processed, stopping when the end of file is reached or another
machine or a default token is encountered.

@item default
This is the same as machine name except that default matches any name.
There can be only one default token, and it must be after all machine
tokens.  This is normally used as:

@example
default login anonymous password user@@site
@end example

thereby giving the user automatic anonymous ftp login to machines not
specified in @file{.netrc}.  This can be overridden by using the
@option{-n} flag to disable auto-login.

@item login name
Identify a user on the remote machine.  If this token is present, the
auto-login process will initiate a login using the specified name.

@item password string
Supply a password.  If this token is present, the auto-login process
will supply the specified string if the remote server requires a
password as part of the login process.  Note that if this token is
present in the @file{.netrc} file for any user other than anonymous,
@command{ftp} will abort the auto-login process if the @file{.netrc}
is readable by anyone besides the user.

@item account string
Supply an additional account password.  If this token is present, the
auto-login process will supply the specified string if the remote
server requires an additional account password, or the auto-login
process will initiate an @code{ACCT} command if it does not.

@item macdef name
Define a macro.  This token functions like the @command{ftp}
@code{macdef} command functions.  A macro is defined with the
specified name; its contents begin with the next @file{.netrc} line
and continue until a null line (consecutive new-line characters) is
encountered.  If a macro named init is defined, it is automatically
executed as the last step in the auto-login process.
@end table

@command{ftp} utilizes the following environment variables.

@table @env
@item HOME
For default location of a @file{.netrc} file, if one exists.

@item SHELL
For default shell.
@end table

Correct execution of many commands depends upon proper behavior by the
remote server.

An error in the treatment of carriage returns in the 4.2BSD ascii-mode
transfer code has been corrected.  This correction may result in
incorrect transfers of binary files to and from 4.2BSD servers using
the ascii type.  Avoid this problem by using the binary image type.

@node tftp invocation
@chapter @command{tftp}: TFTP client
@cindex tftp

@command{tftp} is the user interface to the Internet TFTP, Trivial
File Transfer Protocol, which allows users to transfer files to and
from a remote machine.  The remote host may be specified on the
command line, in which case @command{tftp} uses host as the default
host for future transfers.

@example
tftp [@var{option}]@dots{} @var{host}
@end example

@section Commands

Once @command{tftp} is running, it issues the prompt and recognizes
the following commands:

@table @code
@item ? @var{command-name}
Print help information.

@item ascii
Shorthand for @code{mode ascii}

@item binary
Shorthand for @code{mode binary}

@item connect @var{host-name} [@var{port}]
Set the host (and optionally port) for transfers.  Note that the TFTP
protocol, unlike the FTP protocol, does not maintain connections
between transfers; thus, the connect command does not actually create
a connection, but merely remembers what host is to be used for
transfers.  You do not have to use the connect command; the remote
host can be specified as part of the get or put commands.

@item get @var{file-name}
@itemx get @var{remotename} @var{localname}
@itemx get @var{file}@dots{}
Get a file, or a set of files, from the specified sources.  The source can
be in one of two forms: a file name on the remote host, if the host has
already been specified, or a string of the form @samp{host:filename}
to specify both a host and file name at the same time.  If the latter
form is used, the last hostname specified becomes the default for
future transfers.  When specifying a numeric IPv6 address as host
part, then this address must be enclosed between square brackets,
since it contains colons and would interfere with the delimiter
before the file name.  Brackets are optional for IPv4 addresses.

@example
tftp> get [2001:1234::12]:issue
@end example

@item mode @var{transfer-mode}
Set the mode for transfers; @var{transfer-mode} may be one of
@samp{ascii} or @samp{binary}.  The default is @samp{ascii}.

@item put @var{file}
@itemx put @var{localfile} @var{remotefile}
@itemx put @var{file}@dots{} @var{remote-directory}
Put a file or set of files to the specified remote file or directory.
The destination can be in one of two forms: a filename on the remote
host, if the host has already been specified, or a string of the form
@samp{host:filename} to specify both a host and filename at the same
time.  If the latter form is used, the hostname specified becomes the
default for future transfers.  If the @file{remote-directory} form is
used, the remote host is assumed to be a UNIX machine.  The same use
of square brackets for enclosing numeric IPv6 addresses applies here,
as was mentioned for the command @command{get}.

@item quit
Exit @command{tftp}.  An end of file also exits.

@item rexmt @var{retransmission-timeout}
Set the per-packet retransmission timeout, in seconds.

@item status
Show current status.

@item timeout @var{total-transmission-timeout}
Set the total transmission timeout, in seconds.

@item trace
Toggle packet tracing.

@item verbose
Toggle verbose mode.
@end table

Because there is no user-login or validation within the @command{tftp}
protocol, the remote site will probably have some sort of file-access
restrictions in place.  The exact methods are specific to each site
and therefore difficult to document here.

@node rsh invocation
@chapter @command{rsh}: Remote shell
@cindex rsh

@command{rsh} executes command on host and copies its standard input
to the remote command, the standard output of the remote command to
its standard output, and the standard error of the remote command to
its standard error.  Interrupt, quit and terminate signals are
propagated to the remote command; @command{rsh} normally terminates
when the remote command does.

When using the @command{rsh} command, you can create a link to your
path using a host name as the link name.  For example:

@example
# ln -s /usr/bin/rsh @var{hostname}
# @var{hostname} ls
@end example

@var{hostname} will be passed to @command{rsh} as the default host.

@command{rsh} allows access to the remote host without the use of a
passwd.  For details, @xref{rcmd, , rcmd, libc, The GNU C Library
Reference Manual}.

@section Invoking

The options are as follows :

@table @option
@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Use only IPv4.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Use only IPv6.

@item -d
@itemx --debug
@opindex -d
@opindex --debug
Turns on socket debugging used for communication with the remote host.

@item -k @var{realm}
@itemx --realm=@var{realm}
@opindex -k
@opindex --realm
The option requests rsh to obtain tickets for the remote host in
realm @var{realm} instead of the remote host's realm.

@item -K
@itemx --kerberos
@opindex -K
@opindex --kerberos
Turns off all Kerberos authentication.

@item -l @var{user}
@itemx --user=@var{user}
@opindex -l
@opindex --user
By default, the remote username is the same as the local username.
The @option{-l} option and the @samp{username@@host} format allow the
remote user name to be specified.  Kerberos authentication is used,
whenever available, and authorization is determined as in @command{rlogin}
(@pxref{rlogin invocation}).

@item -n
@itemx --no-input
@opindex -n
@opindex --no-input
Use @file{/dev/null} for all input, and use no separate @samp{stderr}
at remote end.  This option is void together with encryption.

@item -x
@itemx --encrypt
@opindex -x
@opindex --encrypt
Turns on encryption for all data passed via the rsh session.  This
may impact response time and CPU utilization, but provides increased
security.
@end table

If no command is specified, you will be logged in on the remote host
using @command{rlogin}.

@c FIXME: I do not follow the example, what is OTHER_REMOTEFILE?

Shell metacharacters which are not quoted are interpreted on the local
machine, while quoted metacharacters are interpreted on the remote
machine.  For example:

@example
rsh otherhost cat remotefile >> localfile
rsh otherhost cat remotefile ">> "localfile
@end example

The first command appends the remote file file @file{remotefile} to
the local file @file{localfile}, while the later command appends
@file{remotefile} to @file{other_remotefile}.

@node rlogin invocation
@chapter @command{rlogin}: Remote login
@cindex rlogin

@command{rlogin} command logs into a specified remote host and
connects your local terminal to the remote host.  The remote terminal
type is the same as that given in the @env{TERM} local environment
variable.  The terminal or window size is also the same, if the remote
host supports them, and any changes in size are transferred.

When using the @command{rlogin} command, you can create a link to your
path using a host name as the link name.  For example:

@example
# ln -s /usr/bin/rlogin @var{hostname}
# @var{hostname} -8
@end example

Using @var{hostname} automatically uses the @command{rlogin} to log in
to the remote host named @var{hostname}.

@command{rlogin} allows access to the remote host without the use of a
passwd.  For details, @xref{rcmd, , rcmd, libc, The GNU C Library
Reference Manual}.

@section Invoking

The options are as follows :

@table @option
@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Use only IPv4.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Use only IPv6.

@item -8
@itemx --8-bit
@opindex -8
@opindex --8-bit
Allows an eight-bit input data path at all times; otherwise parity
bits are stripped except when the remote side's stop and start
characters are other than @kbd{C-S}/@kbd{C-Q}.

@item -d
@itemx --debug
@opindex -d
@opindex --debug
Turns on socket debugging on the TCP sockets used for communication
with the remote host.

@item -e @var{char}
@itemx --escape=@var{char}
@opindex -e
@opindex --escape
Allows user specification of the escape character, which is @samp{~}
by default.  This specification may be as a literal character, or as
an octal value in the form @samp{\nnn}.

@item -E
@itemx --no-escape
@opindex -E
@opindex --no-escape
Stops any character from being recognized as an escape character.
When used with the @option{-8} option, this provides a completely
transparent connection.

@item -k @var{realm}
@itemx --realm=@var{realm}
@opindex -k
@opindex --realm
The option requests rlogin to obtain tickets for the remote host in
realm @var{realm} instead of the remote host's realm.

@item -K
@itemx --kerberos
@opindex -K
@opindex --kerberos
Turns off all Kerberos authentication.

@item -l @var{user}
@itemx --user=@var{user}
@opindex -l
@opindex --user
By default, the remote username is the same as the local username.
This option, and the @samp{user@@host} format, allow the remote
user name to be made explicit, or changed.

@item -x
@itemx --encrypt
@opindex -x
@opindex --encrypt
Turns on encryption for all data passed via the rlogin session.
This may impact response time and CPU utilization, but provides
increased security.
@end table

A line of the form @kbd{@var{escape-char}.} disconnects from the
remote host.  Similarly, the line @kbd{@var{escape-char}C-Z} will
suspend the rlogin session, and
@kbd{@var{escape-char}@var{delayed-suspend-char}} suspends the send
portion of the @command{rlogin}, but allows output from the remote
system.  By default, the tilde (@samp{~) character} is the
@var{escape-char}, and normally @kbd{C-Y} is the
@var{delayed-suspend-char}.

All echoing takes place at the remote site, so that (except for
delays) the @command{rlogin} is transparent.  Flow control via
@kbd{C-S}/@kbd{C-Q}, if supported, stop and start the flow of
information, flushing of input and output on interrupts are handled
properly.

On the server side the @code{iruserok} and @code{ruserok} functions
are used to authenticate, see the appropriate man page for more
information, if supported.

@section Kerberos Authentication

If @command{rlogin} was compiled with kerberos support, options
@option{-x}, @option{-k}, @option{-K} are available.  Each user may
have a private authorization list in the file @file{.klogin} in their
home directory.  Each line in this file should contain a Kerberos
principal name of the form @samp{principal.instance@@realm}.  If the
originating user is authenticated to one of the principals named in
@file{.klogin}, access is granted to the account.  The principal
@samp{accountname.@@localrealm} is granted access if there is no
@file{.klogin} file.  Otherwise a login and password will be prompted
for on the remote machine as in @command{login}.  To avoid certain
security problems, the @file{.klogin} file must be owned by the remote
user.  If Kerberos authentication fails, a warning message is printed
and the standard Berkeley rlogin is used instead.

@node rcp invocation
@chapter @command{rcp}: Copy files between machines
@cindex rcp

@command{rcp} copies files between machines.  Each file or directory
argument is either a remote file name of the form
@samp{rname@@rhost:path}, or a local file name (containing no @samp{:}
characters, or a @samp{/} before any @samp{:}s).

@example
rcp [@var{option}]@dots{} @var{old-file} @var{new-file}
rcp [@var{option}]@dots{} @var{files}@dots{} @var{directory}
@end example

@table @option
@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Use only IPv4.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Use only IPv6.

@item -d @var{directory}
@itemx --target-directory=@var{directory}
@opindex -d
@opindex --target-directory
Copy all source arguments into @var{directory}.

@item -f
@itemx --from
@opindex -f
@opindex --from
(Server mode only.) Copying from remote host.

@item -k @var{realm}
@itemx --realm=@var{realm}
@opindex -k
@opindex --realm
The option requests rcp to obtain tickets for the remote host in
realm @var{realm} instead of the remote host's realm.

@item -K
@itemx --kerberos
@opindex -K
@opindex --kerberos
Turns off all Kerberos authentication.

@item -p
@itemx --preserve
@opindex -p
@opindex --preserve
Causes @code{rcp} to attempt to preserve (duplicate) in its copies the
modification times and modes of the source files, ignoring the umask.
By default, the mode and owner of the target file are preserved
if the target itself already exists; otherwise the mode of the source
file is modified by the @code{umask} setting on the destination host.

@item -r
@itemx --recursive
@opindex -r
@opindex --recursive
If any of the source files are directories, @command{rcp} copies each
subtree rooted at that name; in this case the destination must be a
directory.

@item -t
@itemx --to
@opindex -t
@opindex --to
(Server mode only.) Copying to remote host.

@item -x
@itemx --encrypt
@opindex -x
@opindex --encrypt
Turns on encryption for all data passed via the @command{rcp} session.
This may impact response time and CPU utilization, but provides increased
security.

@end table

@command{rcp} doesn't detect all cases where the target of a copy
might be a file in cases where only a directory should be legal.

@command{rcp} can be confused by any output generated by commands in a
@file{.login}, @file{.profile}, or @file{.cshrc} file on the remote
host.

The destination user and hostname may have to be specified as
@samp{rhost.rname} when the destination machine is running the 4.2BSD
version of @command{rcp}.

@node rexec invocation
@chapter @command{rexec}: a remote execution program
@cindex rexec

@command{rexec} is a program that executes a program on another host.

@example
rexec --user=@var{login} --password=@var{pass} --host=@var{host}  \
      [OPTION] @var{command}
@end example

The command line arguments are as follows:

@table @option
@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Use only IPv4 connections as all times.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Use only IPv6 connections.

@item -a
@itemx --ipany
@opindex -a
@opindex --ipany
Allow any address family for connections.  This is the default.

@item -e
@itemx --error=@var{port}
@opindex -e
@opindex --error
Specify the TCP port to use for stderr redirection, in case it is not
specified a random port will be used.

@item -h
@item --host=@var{name}
@opindex -h
@opindex --host
Specify the host with whom to connect: symbolic name or address.

@item -n
@itemx --noerr
@opindex -n
@opindex --noerr
If specified, an error stream will not be created.

@item -p
@itemx --password=@var{passwd}
@opindex -p
@opindex --password
Specify the password for logging-in.  The special value
consisting of a single dash @samp{-} will make @command{rexec}
read a single line from stdin.  This input is then used
as password and is passed as such to the remote server.
Thus it is possible to hide vital access information
slightly better than the full disclosure implicit in
the text of a command line option.

@item -P
@itemx --port=@var{num}
@opindex -P
@opindex --port
Specify to which numerical port a connection shall be sought.
If it is not specified, then use port 512/tcp by default.

@item -u
@itemx --user=@var{name}
@opindex -u
@opindex --user
Specify the user with whom to log into the server.
@end table


@node talk invocation
@chapter @command{talk}: a communication program
@cindex talk

@command{talk} is a visual communication program which copies lines
from your terminal to that of another user.

@section Invoking

The command line arguments are as follows:

@table @var
@item person
If you wish to talk to someone on your own machine, then person is
just the person's login name.  If you wish to talk to a user on
another host, then person is of the form @samp{user@@host}.

@item ttyname
If you wish to talk to a user who is logged in more than once, the
@var{ttyname} argument may be used to indicate the appropriate
terminal name, where @var{ttyname} is of the form @samp{ttyXX}.
@end table

When first called, talk sends the message:

@example
Message from TalkDaemon@@his_machine@dots{}
talk: connection requested by your_name@@your_machine.
talk: respond with: talk your_name@@your_machine
@end example

to the user you wish to talk to.  At this point, the recipient of the
message should reply by typing:

@example
talk @var{your_name}@@@var{your_machine}
@end example

It doesn't matter from which machine the recipient replies, as long as
his login-name is the same.  Once communication is established, the
two parties may type simultaneously, with their output appearing in
separate windows.  Typing @kbd{C-L} will cause the screen to be
reprinted, while your erase, kill, and word kill characters will
behave normally.  To exit, just type your interrupt character; talk
then moves the cursor to the bottom of the screen and restores the
terminal to its previous state.

Permission to talk may be denied or granted by use of the
@command{mesg} command.  At the outset talking is allowed.  Certain
commands, in particular @command{nroff} and @command{pr}, disallow
messages in order to prevent messy output.

To exit, just type your interrupt character; talk then moves the
cursor to the bottom of the screen and restores the terminal to its
previous state.

@node telnet invocation
@chapter @command{telnet}: User interface to TELNET

Login to a remote system HOST, optionally using a (non-standard)
service port PORT:

@example
telnet [@var{OPTION}...] [@var{HOST} [@var{PORT}]]
@end example

@table @option
@item -4
@itemx --ipv4
Use only IPv4.

@item -6
@itemx --ipv6
Use only IPv6.

@item -8
@itemx --binary
Use an 8-bit data path.

@item -a
@itemx --login
Attempt automatic login.

@item -c
@itemx --no-rc
Do not read the user's file @file{$HOME/.telnetrc}.

@item -d
@itemx --debug
Turn on debugging.

@item -e CHAR
@itemx --escape=CHAR
Use CHAR as escape character.

@item -E
@itemx --no-escape
Use no escape character.

@item -K
@itemx --no-login
Do not automatically login to the remote system.

@item -l USER
@itemx --user=USER
Attempt automatic login as USER.

@item -L
@itemx --binary-output
Use an 8-bit data path for output only.

@item -n FILE
@itemx --trace=FILE
Record trace information into FILE.

@item -r
@itemx --rlogin
Display a user-interface similar to that of @command{rlogin}.

@item -x
@itemx --encrypt
If possible, encrypt the data stream.

@item -X ATYPE
@itemx --disable-auth=ATYPE
Disable authentication of type ATYPE.
Use this option multiple times if more than one type
is to be disabled.  Standard choices are @samp{null},
@samp{kerberos_v4}, and @samp{kerberos_v5}.
@end table

@node inetd invocation
@chapter @command{inetd}: Interner super-server
@cindex inetd

@command{inetd} program should be run at boot time by /etc/rc.  It
then listens for connections on certain internet sockets.  When a
connection is found on one of its sockets, it decides what service the
socket corresponds to, and invokes a program to service the request.
The server program is invoked with the service socket as its standard
input, output and error descriptors.  After the program is finished,
inetd continues to listen on the socket (except in some cases which
will be described below).  Essentially, inetd allows running one
daemon to invoke several others, reducing load on the system.

There are two types of services that inetd can start: standard and
TCPMUX.  A standard service has a well-known port assigned to it; it
may be a service that implements an official Internet standard or is a
BSD-specific service.  As described in RFC 1078, TCPMUX services are
nonstandard services that do not have a well-known port assigned to
them.  They are invoked from inetd when a program connects to the
``tcpmux'' well-known port and specifies the service name.  This
feature is useful for adding locally-developed servers.

@menu
* Invocation::
* Configuration file::
* Built-in services::
* TCPMUX::
* Inetd Environment::
* Error Messages::
@end menu

@node Invocation
@section Invocation

Normally, @command{inetd} is invoked without any arguments.  It does,
however, support several command line options.  These are:

@table @option
@opindex -d
@opindex --debug
@item -d
@itemx --debug
Turns on debugging.  With this option, @command{inetd} stays in
foreground and prints additional debugging information of stderr.

@item -R @var{rate}
@itemx --rate=@var{rate}
@opindex --r
@opindex --rate
Specifies the maximum number of times a service can be invoked in one
minute; the default is 1000.

@opindex --environment
@item --environment
Pass local and remote socket information in environment variables.
@xref{Inetd Environment}.

@opindex --resolve
@item --resolve
Resolve IP addresses when setting environment variables.  @xref{Inetd
Environment}.
@end table

@node Configuration file
@section Configuration file

Upon execution, inetd reads its configuration information from a
configuration pathnames on the command line, by default,
@file{/etc/inetd.conf} and @file{/etc/initd.d}.  If the configuration
pathname is a directory, all the files in the directory are read like
a configuration file.  All of the configuration files are read and
merged.  There must be an entry for each field in the configuration
file, with entries for each field separated by a tab or a space.
Comments are denoted by a ``#'' at the beginning of a line.  There
must be an entry for each field.  The fields of the configuration file
are summarized in the table below (optional parts are enclosed in
square brackets:

@table @asis
@item [service node:]service name
The service-name entry is the name of a valid service in the file
@file{/etc/services}.  For ``internal'' services (@pxref{Built-in
services}), the service name must be the official name of the service
(that is, the first entry in @file{/etc/services}), or a numeric
representation thereof.  For TCPMUX services, the value of the
@samp{service name} field consists of the string @samp{tcpmux}
followed by a slash and the locally-chosen service name
(@pxref{TCPMUX}).

Optional @samp{service node} prefix is allowed for internet services.
When present, it supplies the local addresses @command{inetd} should
use when listening for that service.  @samp{Service node} consists of
a comma-separated list of addresses.  Both symbolic host names and
numeric IP addresses are allowed.  Symbolic hostnames are looked up in
DNS service.  If a hostname has multiple address mappings,
@command{inetd} creates a socket to listen on each address.

To avoid repeating an address that occurs frequently, a line with a
host address specifier and colon, but no further fields is allowed,
e.g.:

@smallexample
127.0.0.1,192.168.0.5:
@end smallexample

The address specifier from such a line is remembered and used for all
further lines lacking an explicit host specifier.  Such a default
address remains in effect until another such line or end of the
configuration is encountered, whichever occurs first.

A special hostname @samp{*} stands for @code{INADDR_ANY}.  When used
in a normal configuration line, it causes the default address
specifier to be ignored for that line.  When used in a default address
specification, e.g.:

@smallexample
*:
@end smallexample

it causes any previous default address specifier to be forgotten.

@item socket type
The socket type should be one of @samp{stream}, @samp{dgram},
@samp{raw}, @samp{rdm}, or @samp{seqpacket}, depending on whether the
socket is a stream, datagram, raw, reliably delivered message, or
sequenced packet socket.  TCPMUX services must use @samp{stream}.

@item protocol
The protocol must be a valid protocol as given in
@file{/etc/protocols}.  Examples might be @samp{tcp} or @samp{udp}.
TCPMUX services must use @samp{tcp}.  If IPv6 support is enabled the
sockets will accept both IPv4 and IPv6 connections if that is
supported by the OS.  If inetd should only accept IPv4 or IPv6
connections, add @samp{4} or @samp{6} to the protocol name.  For
example @samp{tcp4} will only accept IPv4 tcp connections and
@samp{udp6} will only accept IPv6 udp connections.

@item wait/nowait[.max]
The @samp{wait/nowait} entry specifies whether the server that is
invoked by @command{inetd} will take over the socket associated with
the service access point, and thus whether inetd should wait for the
server to exit before listening for new service requests.  Datagram
servers must use @samp{wait}, as they are always invoked with the
original datagram socket bound to the specified service address.
These servers must read at least one datagram from the socket before
exiting.  If a datagram server connects to its peer, freeing the
socket so inetd can received further messages on the socket, it is
said to be a ``multi-threaded'' server; it should read one datagram
from the socket and create a new socket connected to the peer.  It
should fork, and the parent should then exit to allow inetd to check
for new service requests to spawn new servers.  Datagram servers which
process all incoming datagrams on a socket and eventually time out are
said to be ``single-threaded''.  @command{comsat} and talkd are both
examples of the latter type of datagram server.  @command{tftpd} is an
example of a multi-threaded datagram server.

Servers using stream sockets generally are multi-threaded and use the
@samp{nowait} entry.  Connection requests for these services are
accepted by inetd, and the server is given only the newly-accepted
socket connected to a client of the service.  Most stream-based
services and all TCPMUX services operate in this manner.  For such
services, the number of running instances of the server can be
limitied by specifying optional @samp{max} suffix (a decimal number),
e.g.: @samp{nowait.15}.

Stream-based servers that use @samp{wait} are started with the
listening service socket, and must accept at least one connection
request before exiting.  Such a server would normally accept and
process incoming connection requests until a timeout.
Other services must use @samp{nowait}.

@item user
The user entry should contain the user name of the user as whom the
server should run.  This allows for servers to be given less
permission than root.  An optional form includes also a group name
as a suffix, separated from the user name by colon or a period, i.e.,
@samp{user:group} or @samp{user.group}.

@item server program
The server-program entry should contain the pathname of the program
which is to be executed by inetd when a request is found on its
socket.  If inetd provides this service internally, this entry should
be @samp{internal}.

It is common usage to specify @file{/usr/sbin/tcpd} in this field.

@item server program arguments
The server program arguments should be just as arguments normally are,
starting with @code{argv[0]}, which is the name of the program.  If
the service is provided internally, this entry must contain the word
@samp{internal}, or be empty.
@end table

@node Built-in services
@section Built-in services

The @command{inetd} program provides several ``trivial'' services
internally by use of routines within itself.  All these services can
operate both in @samp{stream} and in @samp{dgram} mode.  They are:

@table @asis
@item echo
Send back to the originating source any data received from it.  This
is a debugging and measurement tool.

@item discard
Silently throw away any data received.

@item chargen
This is a character generator service.  It can be operated as both
stream or dgram service.  When operating in @samp{stream} mode, once a
connection is established a stream of data is sent out the connection
(and any data received is thrown away).  This continues until the
calling user terminates the connection.  When operating in
@samp{dgram} mode, @command{inetd} listens for UDP datagrams, and for
each received datagram, answers with a datagram containing a random
number (between 0 and 512) of characters.  Any data in the received
datagram are ignored.

@item daytime
Send back the current date and time in a human readable form.  Any
input is discarded.

@item time
Send back the current date and time as a 32-bit integer number,
nrepresenting the number of seconds since midnight, January 1, 1900.
@end table

@node TCPMUX
@section TCPMUX
The TCPMUX protocol.

@quotation
A TCP client connects to a foreign host on TCP port 1.  It sends the
service name followed by a carriage-return line-feed <CRLF>.  The
service name is never case sensitive.  The server replies with a
single character indicating positive (+) or negative (-)
acknowledgment, immediately followed by an optional message of
explanation, terminated with a <CRLF>.  If the reply was positive, the
selected protocol begins; otherwise the connection is closed.''  The
program is passed the TCP connection as file descriptors 0 and 1.
@end quotation

If the TCPMUX service name begins with a ``+'', @command{inetd}
returns the positive reply for the program.  This allows you to invoke
programs that use stdin/stdout without putting any special server code
in them.

The special service name @samp{help} causes inetd to list TCPMUX
services in @file{inetd.conf}.

To define TCPMUX services, the configuration file must contain a
@samp{tcpmux internal} definition.

Here are several example service entries for the various types of
services:

@example
ftp           stream  tcp   nowait root  /usr/libexec/ftpd       ftpd -l
ntalk         dgram   udp   wait   root  /usr/libexec/ntalkd     ntalkd
tcpmux        stream  tcp   nowait root  internal
tcpmux/+date  stream  tcp   nowait guest /bin/date               date
tcpmux/phonebook stream tcp nowait guest /usr/bin/phonebook      phonebook
@end example

@node Inetd Environment
@section Inetd Environment

If a connection is made with a streaming protocol (@samp{stream}) and
if @option{--environment} option has been given, @command{inetd} will
set the following environment variables before starting the program:

@table @env
@item PROTO
Always @samp{TCP}.

@item TCPLOCALIP
Local IP address of the interface which accepted the connection.

@item TCPLOCALPORT
Port number on which the TCP connection was established.

@item TCPREMOTEIP
IP address of the remote client.

@item TCPREMOTEPORT
Port number on the client side of the TCP connection.
@end table

Additionally, if given the @option{--remote} option, @command{inetd}
sets the following environment variables:

@table @env
@item TCPLOCALHOST
DNS name of @env{TCPLOCALIP}.

@item TCPREMOTEHOST
DNS name of @env{TCPREMOTEIP}.
@end table

@node Error Messages
@section Error Messages

The inetd server logs error messages using syslog.  Important error
messages and their explanations are:

@table @samp
@item service/protocol server failing (looping), service terminated.
The number of requests for the specified service in the past minute
exceeded the limit.  The limit exists to prevent a broken program or a
malicious user from swamping the system.  This message may occur for
several reasons:

@enumerate 1
@item there are lots of hosts requesting the service within a short time period,
@item a ``broken'' client program is requesting the service too frequently,
@item a malicious user is running a program to invoke the service in a ``denial of service'' attack,
@item the invoked service program has an error that causes clients to retry quickly.
@end enumerate

Use the @option{-R} option, as described above, to change the rate
limit.  Once the limit is reached, the service will be reenabled
automatically in 10 minutes.

@item service/protocol: No such user 'user', service ignored
@itemx service/protocol: getpwnam: user: No such user
No entry for user exists in the passwd file.  The first message occurs
when inetd (re)reads the configuration file.  The second message
occurs when the service is invoked.

@item service/protocol: No such user 'user', service ignored
@itemx service/protocol: getpwnam: user: No such user
No entry for user exists in the passwd file.  The first message occurs
when inetd (re)reads the configuration file.  The second message
occurs when the service is invoked.

@item service: can't set uid number
@itemx service: can't set gid number
The user or group ID for the entry's user is invalid.
@end table

@node syslogd invocation
@chapter @command{syslogd}: system service logging faclity
@cindex syslogd

@command{syslogd} is a system service that provides error logging
facility.  Messages are read from the UNIX domain socket
@file{/dev/log}, from an Internet domain socket specified in
@file{/etc/services}, and from the special device @file{/dev/klog} (to
read kernel messages).

@command{syslogd} creates the file @file{/var/run/syslog.pid}, and
stores its process id there.  This can be used to kill or reconfigure
@command{syslogd}.

The message sent to @command{syslogd} should consist of a single line.
The message can contain a priority code, which should be a preceding
decimal number in angle braces, for example, @code{<5>}.  This
priority code should map into the priorities defined in the include
file @code{sys/syslog.h}.

@example
syslogd [@var{options}]@dots{}
@end example

@table @option
@item -f @var{file}
@itemx --rcfile=@var{file}
@opindex -f
@opindex --rcfile
Override configuration (the default file is @file{/etc/syslog.conf}).

@item --pidfile=@var{file}
@opindex --pidfile
Override pidfile (the default file is @file{/var/run/syslogd.pid}).

@item -n
@itemx --no-detach
@opindex -n
@opindex --no-detach
Do not enter daemon mode.

@item -d
@itemx --debug
@opindex -d
@opindex --debug
Print debug information (implies @option{-n}).

@item -p @var{file}
@itemx --socket=@var{file}
@opindex -p
@opindex --socket
Override default UNIX domain socket @file{/dev/log}.

@item -a @var{socket}
Add UNIX socket to listen.  An unlimited number of sockets is allowed.

@item -r
@itemx --inet
@opindex -r
@opindex --inet
Receive remote messages via Internet domain socket.
Without this option no remote massages are received,
since there is no listening socket. Yet sockets for
forwarding are created on the fly as needed,
which might cause performance issues on busy systems.

@item -b @var{address}
@itemx --bind=@var{address}
@opindex -b
@opindex --bind
Restrict the listening Internet domain socket to a single address.
The default (given the use of @option{-r}) is a wildcard address,
implying that the server listens at every available address.
Any name will be resolved, and the lookup result will depend
on the options @option{-4}, @option{-6}, and @option{--ipany}.

@item --no-unixaf
@opindex --no-unixaf
Do not listen on UNIX domain sockets (overrides @option{-a} and
@option{-p}).

@item --no-klog
@opindex --no-klog
Do not listen to the kernel log device @file{/dev/klog}.

@item --ipany
@opindex --ipany
Allow both address families: IPv4 and IPv6.

@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Use only IPv4 for Internet domain sockets.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Use only IPv6 for Internet domain sockets.

@item --no-forward
@opindex --no-forward
Do not forward any messages (overrides @option{-h}).
This disables even temporary creation of forwarding
sockets, an ability which is otherwise active when
the option @option{-r} is left out.

@item -h
@itemx --hop
@opindex -h
@opindex --hop
Forward messages from remote hosts.

@item -m @var{interval}
@itemx --mark=@var{interval}
@opindex -m
@opindex --mark
Specify timestamp interval in logs (0 for no timestamps).

@item -l @var{hostlist}
@opindex -l
Log hosts in @var{hostlist} by their hostname.  Multiple lists are
allowed.

@item -s @var{domainlist}
@opindex -s
List of domains which should be stripped from the FQDN of hosts before
logging their name.  Multiple lists are allowed.
@end table

@section Configuration file

@command{syslogd} reads its configuration file when it starts up and
whenever it receives a hangup signal.  The @file{syslog.conf} file is
the configuration file for the @command{syslogd} program.  It consists
of lines with two fields: the @dfn{selector} field which specifies the
types of messages and priorities to which the line applies, and an
@dfn{action} field which specifies the action to be taken if a message
@command{syslogd} receives matches the selection criteria.  The
selector field is separated from the action field by one or more tab
or space characters.  A rule can be splitted in several lines if all
lines except the last are terminated with a backslash @samp{\}.

The Selectors function are encoded as a facility, a period (@samp{.}),
and a level, with no intervening white-space.  Both the facility and
the level are case insensitive.

The facility describes the part of the system generating the message,
and is one of the following keywords: @samp{auth}, @samp{authpriv},
@samp{cron}, @samp{daemon}, @samp{kern}, @samp{lpr}, @samp{mail},
@samp{mark}, @samp{news}, @samp{syslog}, @samp{user}, @samp{uucp} and
@samp{local0} through @samp{local7}.  These keywords (with the
exception of @samp{mark}) correspond to the similar @samp{LOG_} values
specified to the @samp{openlog} and @samp{syslog} library routines.
@xref{Syslog, , Syslog, libc, The GNU C Library Reference Manual}, for
details.

The level describes the severity of the message, and is a keyword from
the following ordered list (higher to lower): @samp{emerg},
@samp{alert}, @samp{crit}, @samp{err, warning}, @samp{notice} and
@samp{debug}.  These keywords correspond to the similar @samp{LOG_}
values specified to the syslog library routine.

@xref{syslog; vsyslog, , syslog and vsyslog, libc, The GNU C Library
Reference Manual}, for a further descriptions of both the facility and
level keywords and their significance.

If a received message matches the specified facility and is of the
specified level (or a higher level), the action specified in the
action field will be taken.

Multiple selectors may be specified for a single action by separating
them with semicolon (@samp{;}) characters.  It is important to note,
however, that each selector can modify the ones preceding it.

Multiple facilities may be specified for a single level by separating
them with comma (@samp{,}) characters.

An asterisk (@samp{*}) can be used to specify all facilities or all
levels.  Two asterisks (@samp{**}) specifie all facilities not named
previously in the configuration file.

By default, a level applies to all messages with the same or higher
level.  The equal (@samp{=}) character can be prepended to a level to
restrict this line of the configuration file to messages with the very
same level.

An exclamation mark (@samp{!}) prepended to a level or the asterisk
means that this line of the configuration file does not apply to the
specified level (and higher ones).  In conjunction with the equal
sign, you can exclude single levels as well.

The special facility @samp{mark} receives a message at priority
@samp{info} every 20 minutes.  This is not enabled by a facility field
containing an asterisk.

The special level @samp{none} disables a particular facility.

The action field of each line specifies the action to be taken when
the selector field selects a message.  There are five forms:

@itemize @bullet
@item
A pathname (beginning with a leading slash).  Selected messages are
appended to the file.

You may prepend a minus (@samp{-}) to the path to omit syncing the
file after each message log.  This can cause data loss at system
crashes, but increases performance for programs which use logging
extensively.

@item
A named pipe, beginning with a vertical bar (@samp{|}) followed by a
pathname.  The pipe must be created with @command{mkfifo} before
@command{syslogd} reads its configuration file.  This feature is
especially useful for debugging.

@item
A hostname (preceded by an at (@samp{@@}) sign).  Selected messages
are forwarded to @command{syslogd} on the named host.

@item
A comma separated list of users.  Selected messages are written to
those users if they are logged in.

@item
An asterisk.  Selected messages are written to all logged-in users.

Blank lines and lines whose first non-blank character is a hash
(@samp{#}) character are ignored.
@end itemize

A configuration file might appear as follows:

@example
# Log all kernel messages, authentication messages of
# level notice or higher and anything of level err or
# higher to the console.
# Don't log private authentication messages!
*.err;kern.*;auth.notice;authpriv.none  /dev/console

# Log anything (except mail) of level info or higher.
# Don't log private authentication messages!
*.info;mail.none;authpriv.none          /var/log/messages

# The authpriv file has restricted access.
authpriv.*                              /var/log/secure

# Log all the mail messages in one place.
mail.*                                  /var/log/maillog

# Everybody gets emergency messages, plus log them on another
# machine.
*.emerg                                 *
*.emerg                                 @@arpa.berkeley.edu

# Root and Eric get alert and higher messages.
*.alert                                 root,eric

# Save mail and news errors of level err and higher in a
# special file.
uucp,news.crit                          /var/log/spoolerr
@end example

The effects of multiple selectors are sometimes not intuitive.  For
example @samp{mail.crit,*.err} will select the @samp{mail} facility
messages at the level of @samp{err} or higher, not at the level of
@samp{crit} or higher.

@node ftpd invocation
@chapter @command{ftpd}: FTP daemon
@cindex ftpd

@command{ftpd} is the Internet File Transfer Protocol server process.
The server uses the TCP protocol and listens at the port specified in
the @samp{ftp} service specification.

@example
ftpd [@var{option}]@dots{}
@end example

@table @option
@item -4
@itemx --ipv4
@opindex -4
@opindex --ipv4
Daemon uses only IPv4 addressing.  Ignored in inetd mode.

@item -6
@itemx --ipv6
@opindex -6
@opindex --ipv6
Daemon uses only IPv6 addressing.  Ignored in inetd mode.

@item -A
@itemx --anonymous-only
@opindex -A
@opindex --anonymous-only
Only anonymous login is allowed.

@item -a @var{auth}
@item --auth=@var{auth}
@opindex -a
@opindex --auth
Specify what authentication mechanism to use for incoming connections.
Possible values are: @samp{kerberos}, @samp{kerberos5}, @samp{opie}
and @samp{default}.

Anonymous logins will continue to work when this option is used.

@item  -D
@itemx --daemon
@opindex --daemon
@opindex -D
@command{ftpd} enters daemon-mode.  That allows @command{ftpd} to be
run without @command{inetd}.

@item -d
@itemx --debug
@opindex -d
@opindex --debug
Debugging information is written to the @code{syslog} using facility
@samp{LOG_FTP}.

@item -l
@itemx --logging
@opindex -l
@opindex --logging
Each successful and failed ftp session is logged using @code{syslog}
with a facility of @samp{LOG_FTP}.  If this option is specified twice,
the retrieve (@code{get}), store (@code{put}), append, delete, make
directory, remove directory and rename operations and their filename
arguments are also logged.

@item -p @var{pidfile}
@item --pidfile=@var{pidfile}
@opindex -p
@opindex --pidfile
Change default location of @var{pidfile}.

@item -q
@item --no-version
@opindex -q
@opindex --no-version
Quiet mode.  No information about the version of the @command{ftpd} is
given to the client.

@item -T
@item --max-timeout
@opindex -T
@opindex --max-timeout
A client may also request a different timeout period; the maximum
period allowed may be set to timeout seconds with the @option{-T}
option.  The default limit is 2 hours.

@item -t @var{timeout}
@item --timeout=@var{timeout}
@opindex -t
@opindex --timeout
The inactivity timeout period is set to timeout seconds (the default
is 15 minutes).

@item -u @var{umask}
@item --umask=@var{umask}
@opindex -u
@opindex --umask
Set default umask(base 8).
@end table

The file @file{/etc/nologin} can be used to disable FTP access.  If
the file exists, @command{ftpd} displays it and exits.  If the file
@file{/etc/ftpwelcome} exists, @command{ftpd} prints it before issuing
the @samp{ready} message.  If the file @file{/etc/motd} exists,
@command{ftpd} prints it after a successful login.

The FTP server currently supports the following FTP requests.  The
case of the requests is ignored.

@multitable @columnfractions 0.3 0.7
@headitem Request  @tab  Description
@item ABOR         @tab  abort previous command
@item ACCT         @tab  specify account (ignored)
@item ALLO         @tab  allocate storage (vacuously)
@item APPE         @tab  append to a file
@item CDUP         @tab  change to parent of current working directory
@item CWD          @tab  change working directory
@item DELE         @tab  delete a file
@item EPSV         @tab  extended passive transfer request
@item EPRT         @tab  specify data connection port
@item HELP         @tab  give help information
@item LIST         @tab  give list files in a directory (``ls -lgA'')
@item LPRT         @tab  specify data connection port
@item LPSV         @tab  long passive transfer request
@item MKD          @tab  make a directory
@item MDTM         @tab  show last modification time of file
@item MODE         @tab  specify data transfer mode
@item NLST         @tab  give name list of files in directory
@item NOOP         @tab  do nothing
@item PASS         @tab  specify password
@item PASV         @tab  prepare for server-to-server transfer
@item PORT         @tab  specify data connection port
@item PWD          @tab  print the current working directory
@item QUIT         @tab  terminate session
@item REST         @tab  restart incomplete transfer
@item RETR         @tab  retrieve a file
@item RMD          @tab  remove a directory
@item RNFR         @tab  specify rename-from file name
@item RNTO         @tab  specify rename-to file name
@item SITE         @tab  non-standard commands
@item SIZE         @tab  return size of file
@item STAT         @tab  return status of server
@item STOR         @tab  store a file
@item STOU         @tab  store a file with a unique name
@item STRU         @tab  specify data transfer structure
@item SYST         @tab  show operating system type of server system
@item TYPE         @tab  specify data transfer type
@item USER         @tab  specify user name
@item XCUP         @tab  change to parent of current working directory (deprecated)
@item XCWD         @tab  change working directory (deprecated)
@item XMKD         @tab  make a directory (deprecated)
@item XPWD         @tab  print the current working directory (deprecated)
@item XRMD         @tab  remove a directory (deprecated)
@end multitable

The following non-standard, or UNIX specific, commands are supported by
the @code{SITE} request.

@multitable @columnfractions 0.3 0.7
@item Request      @tab  Description
@item UMASK        @tab  change umask, e.g. @code{SITE UMASK 002}
@item IDLE         @tab  set idle-timer, e.g. @code{SITE IDLE 60}
@item CHMOD        @tab  change mode of a file, e.g. @code{SITE CHMOD0 0CHMOD1 1CHMOD2}
@item HELP         @tab  give help information.
@end multitable

The remaining FTP requests specified in RFC 959 are recognized, but
not implemented.  The extensions @code{MDTM}, @code{REST},
and @code{SIZE} are specified in RFC 3659, while @code{EPRT}
and @code{EPSV} appear in RFC 2428, @code{LPRT} and @code{LPSV}
in RFC 1639.

The ftp server will abort an active file transfer only when the
@code{ABOR} command is preceded by a Telnet @samp{Interrupt Process}
(IP) signal and a Telnet @samp{Synch} signal in the command Telnet
stream, as described in Internet RFC 959.  If a @code{STAT} command is
received during a data transfer, preceded by a Telnet IP and Synch,
transfer status will be returned.

@code{ftpd} interprets file names according to the globbing
conventions used by @command{csh}.  This allows users to utilize the
metacharacters @samp{*?[]@{@}~}.

@command{ftpd} authenticates users according to three rules.

@enumerate
@item
The login name must be in the password data base, @file{/etc/passwd},
and not have a null password.  In this case a password must be
provided by the client before any file operations may be performed.

@item
The login name must not appear in the file @file{/etc/ftpusers}.

@item
The user must have a standard shell.

@item
If the user name is @samp{anonymous} or @samp{ftp}, an anonymous ftp
account must be present in the password file (user @samp{ftp}).  In
this case the user is allowed to log in by specifying any password (by
convention an email address for the user should be used as the
password).
@end enumerate

In the last case, @command{ftpd} takes special measures to restrict
the client's access privileges.  The server performs a chroot to the
home directory of the @samp{ftp} user.  In order that system security
is not breached, it is recommended that the @samp{ftp} subtree be
constructed with care, following these rules:

@table @file
@item ~ftp
Make the home directory owned by @samp{root} and unwritable by anyone.

@item ~ftp/bin
Make this directory owned by @samp{root} and unwritable by anyone
(mode 555).  The program @command{ls} must be present to support the
list command.  This program should be mode 111.

@item ~ftp/etc
Make this directory owned by @samp{root} and unwritable by anyone
(mode 555).  The files @file{passwd} and @file{group} must be present
for the @command{ls} command to be able to produce owner names rather
than numbers.  The password field in @file{passwd} is not used, and
should not contain real passwords.  The file @file{motd}, if present,
will be printed after a successful login.  These files should be mode
444.

@item ~ftp/pub
Make this directory mode 777 and owned by @samp{ftp}.  Guests can then
place files which are to be accessible via the anonymous account in
this directory.
@end table

@section Configuration files

@table @samp
@item @file{/etc/ftpusers}
List of unwelcome/restricted users.

@item @file{/etc/ftpwelcome}
Welcome notice.

@item @file{/etc/motd}
Welcome notice after login.

@item @file{/etc/nologin}
Displayed and access refused.
@end table

@node tftpd invocation
@chapter @command{tftpd}: TFTP server
@cindex tftpd

Synopsis:

@example
tftpd [@var{OPTIONS}]@dots{}
@end example

@table @option
@item -l
Enable logging.

@item -n
Supress negative acknowledgement of requests for nonexistent relative
filenames.
@end table

@node rshd invocation
@chapter @command{rshd}: Remote shell server
@cindex rshd

The @command{rshd} server is the server for the @code{rcmd} routine
and, consequently, for the @command{rsh} (@pxref{rsh invocation})
program.  The server provides remote execution facilities with
authentication based on privileged port numbers from trusted hosts.
The @command{rshd} server listens for service requests at the port
indicated in the @samp{cmd} service specification.  When a service
request is received the following protocol is initiated:

@enumerate
@item
The server checks the client's source port.  If the port is not in the
range 512--1023, the server aborts the connection.  However, this
condition is not applied for Kerberized service.

@item
The server reads characters from the socket up to a NUL (@samp{\0})
byte.  The resultant string is interpreted as an ASCII number, base
10.

@item
If the number received in step 2 is non-zero, it is interpreted as the
port number of a secondary stream to be used for the stderr.  A second
connection is then created to the specified port on the client's
machine.  The source port of this second connection is also in the
range 512--1023.

@item
The server checks the client's source address and requests the
corresponding host name.  If the hostname cannot be determined, the
dot-notation representation of the host address is used.  If the
hostname is in the same domain as the server (according to the last
two components of the domain name), or if the @option{-a} option is
given, the addresses for the hostname are requested, verifying that
the name and address correspond.  If address verification fails, the
connection is aborted with the message, @samp{Host address mismatch.}

@item
A null terminated user name of at most 16 characters is retrieved on
the initial socket.  This user name is interpreted as the user
identity on the client's machine.

@item
A null terminated user name of at most 16 characters is retrieved on
the initial socket.  This user name is interpreted as a user identity
to use on the server's machine.

@item
A null terminated command to be passed to a shell is retrieved on the
initial socket.  The length of the command is limited by the upper
bound on the size of the system's argument list.

@item
Rshd then validates the user using @code{ruserok}, which uses the file
@file{/etc/hosts.equiv} and the @file{.rhosts} file found in the
user's home directory.  The @option{-l} option prevents @code{ruserok}
from doing any validation based on the user's @file{.rhosts} file,
unless the user is the superuser.

@item
If the file @file{/etc/nologin} exists and the user is not the
superuser, the connection is closed.

@item
A null byte is returned on the initial socket and the command line is
passed to the normal login shell of the user.  The shell inherits the
network connections established by @command{rshd}.

@item
Transport-level keepalive messages are enabled unless the @option{-n}
option is present.  The use of keepalive messages allows sessions to
be timed out if the client crashes or becomes unreachable.

@item
The @option{-L} option causes all successful accesses to be logged to
@command{syslogd} (@pxref{syslogd invocation}) as @samp{auth.info}
messages.
@end enumerate

@xref{ruserok, , ruserok, libc, The GNU C Library Reference Manual},
for details.

@section Invoking

The options are as follows:

@table @option
@item -a
@itemx --verify-hostname
@opindex -a
@opindex --verify-hostname
Ask hostname for verification.

@c @item -d
@c @itemx --daemon
@c @opindex -d
@c @opindex --daemon
@c Daemon mode.

@item -k
@itemx --kerberos
@opindex -k
@opindex --kerberos
Use Kerberos authentication.

@item -l
@itemx --no-rhosts
@opindex -l
@opindex --no-rhosts
Ignore @file{.rhosts} file.

@item -L
@itemx --log-sessions
@opindex -L
@opindex --log-sessions
Log successful logins.

@item -n
@itemx --no-keepalive
@opindex -n
@opindex --no-keepalive
Do not set SO_KEEPALIVE.

@item -S @var{name}
@itemx --servername=@var{name}
@opindex -S
@opindex --servername
Set Kerberos server name, overriding canonical hostname.

@item -v
@itemx --vacuous
@opindex -v
@opindex --vacuous
Fail any call asking for non-Kerberos authentication.

@c OBSOLETE?
@c @item -x
@c @itemx --encrypt
@c @opindex -x
@c @opindex --encrypt
@c Turns on DES encryption for all data passed via the @command{rshd}
@c session.  This may impact response time and CPU utilization, but
@c provides increased security.

@c @item -D[@var{level}]
@c @itemx --debug[=@var{level}]
@c @opindex -D
@c @opindex -debug
@c Set debug level, not implemented.

@c @item -o
@c @itemx --allow-root
@c @opindex -o
@c @opindex --allow-root
@c Allow uid == 0 to login, disabled by default

@c @item -p @var{port}
@c @itemx --port=@var{port}
@c @opindex -p
@c @opindex --port
@c Listen on given port (valid only in daemon mode).

@c @item -r
@c @itemx --reverse-required
@c @opindex -r
@c @opindex --reverse-required
@c Required  Require reverse resolving of a remote host IP.
@end table

@section Diagnostics

Except for the last one listed below, all diagnostic messages are
returned on the initial socket, after which any network connections
are closed.  An error is indicated by a leading byte with a value of 1
(0 is returned in step 10 above upon successful completion of all the
steps prior to the execution of the login shell).

@table @samp
@item Locuser too long
The name of the user on the client's machine is longer than 16
characters.

@item Ruser too long
The name of the user on the remote machine is longer than 16
characters.

@item Command too long
The command line passed exceeds the size of the argument list (as
configured into the system).

@item Login incorrect
No password file entry for the user name existed.

@item Remote directory
The chdir command to the home directory failed.

@item Permission denied
The authentication procedure described above failed.

@item Can't make pipe.
The pipe needed for the stderr, wasn't created.

@item Can't fork; try again.
A fork by the server failed.

@item <shellname>: @dots{}
The user's login shell could not be started.  This message is returned
on the connection associated with the stderr, and is not preceded by a
flag byte.
@end table

The authentication procedure used here assumes the integrity of each
client machine and the connecting medium.  This is insecure, but is
useful in an ``open'' environment.

@node rlogind invocation
@chapter @command{rlogind}: Remote login server
@cindex rlogind

@command{rlogind} is the server for the @command{rlogin} program
(@pxref{rlogin invocation}).  The server provides a remote login
facility with authentication based on privileged port numbers from
trusted hosts.

@command{rlogind} listens for service requests at the port indicated
in the @samp{login} service specification.  When a service request is
received the following protocol is initiated:
@enumerate

@item
The server checks the client's source port.  If the port is not in the
range 512-1023, the server aborts the connection.

@item
The server checks the client's source address and requests the
corresponding host name.  If the hostname cannot be determined, the
dot-notation representation of the host address is used.  If the
hostname is in the same domain as the server (according to the last
two components of the domain name), or if the @option{-a} option is
given, the addresses for the hostname are requested, verifying that
the name and address correspond.  Normal authentication is bypassed if
the address verification fails.
@end enumerate

Once the source port and address have been checked, rlogind proceeds
with the authentication process described @ref{rshd invocation}.  It
then allocates a pseudo terminal, and manipulates file descriptors so
that the slave half of the pseudo terminal becomes the stdin, stdout,
and stderr for a login process.  The login process is an instance of
the @command{login} program, invoked with the @option{-f} option if
authentication has succeeded.  If automatic authentication fails, the
user is prompted to log in as if on a standard terminal line.

The parent of the login process manipulates the master side of the
pseudo terminal, operating as an intermediary between the login
process and the client instance of the rlogin program.  In normal
operation, the packet protocol described in @samp{PTY} is invoked to
provide @kbd{C-S}/@kbd{C-Q} type facilities and propagate interrupt
signals to the remote programs.  The login process propagates the
client terminal's baud rate and terminal type, as found in the
environment variable, @env{TERM}.  The screen or window size of the
terminal is requested from the client, and window size changes from
the client are propagated to the pseudo terminal.

Transport-level keepalive messages are enabled unless the @option{-n}
option is client instance of the @code{rlogin} program.  The use of
keepalive messages allows sessions to be timed out if the client
crashes or becomes unreachable.

@xref{ruserok, , ruserok, libc, The GNU C Library Reference Manual},
for details.

@section Invoking

The options are as follows:

@table @option
@item -a
@itemx --verify-hostname
@opindex -a
@opindex --verify-hostname
Ask hostname for verification.

@item -d
@itemx --daemon
@opindex -d
@opindex --daemon
Daemon mode.

@item -D[@var{level}]
@itemx --debug[=@var{level}]
@opindex -D
@opindex -debug
Set debug level, not implemented.

@item -k
@itemx --kerberos
@opindex -k
@opindex --kerberos
Use Kerberos authentication.

@item -l
@itemx --no-rhosts
@opindex -l
@opindex --no-rhosts
Ignore @file{.rhosts} file.

@item -L @var{name}
@itemx --local-domain=@var{name}
@opindex -L
@opindex --local-domain
Set local domain name.

@item -n
@itemx --no-keepalive
@opindex -n
@opindex --no-keepalive
Do not set SO_KEEPALIVE.

@item -o
@itemx --allow-root
@opindex -o
@opindex --allow-root
Allow the root user to login. This is disallowed by default.

@item -p @var{port}
@itemx --port=@var{port}
@opindex -p
@opindex --port
Listen on given port. (Applicable only in daemon mode.)

@item -r
@itemx --reverse-required
@opindex -r
@opindex --reverse-required
Require reverse resolving of remote host's numerical IP.

@item -S @var{name}
@itemx --servername=@var{name}
@opindex -S
@opindex --servername
Set Kerberos server name, overriding canonical hostname.

@item -x
@itemx --encrypt
@opindex -x
@opindex --encrypt
Turns on encryption for all data passed via the @command{rlogind} session.
This may impact response time and CPU utilization, but provides
increased security.

@end table

@section Diagnostics

All initial diagnostic messages are indicated by a leading byte with a
value of 1, after which any network connections are closed.  If there
are no errors before login is invoked, a null byte is returned as in
indication of success.

@table @samp
@item Try again.
A fork by the server failed.
@end table

The authentication procedure used here assumes the integrity of each
client machine and the connecting medium.  This is insecure, but is
useful in an ``open'' environment.

@node rexecd invocation
@chapter @command{rexecd}: server for @code{rexec}
@cindex rexecd

@command{rexecd} is the server for the @code{rexec} routine.  The
server provides remote execution facilities with authentication based
on user names and passwords.  It passes error messages and notices
to the @code{syslog} facility @samp{LOG_DAEMON}.

@example
rexecd [@var{option}]@dots{}
@end example

@command{rexecd} listens for service requests at the port indicated in
the @samp{exec} service specification.  When a service request is
received the following protocol is initiated:

@enumerate
@item
The server reads characters from the socket up to a NUL (@samp{\0})
byte.  The resultant string is interpreted as an ASCII number, base
10.

@item
If the number received in step 1 is non-zero, it is interpreted as the
port number of a secondary stream to be used for the stderr.  A second
connection is then created to the specified port on the client's
machine.

@item
A NUL terminated user name of at most 16 characters is retrieved on
the initial socket.

@item
A NUL terminated, unencrypted password of at most 16 characters is
retrieved on the initial socket.

@item
A NUL terminated command to be passed to a shell is retrieved on the
initial socket.  The length of the command is limited by the upper
bound on the size of the system's argument list.

@item
@command{rexecd} then validates the user as is done at login time and,
if the authentication was successful, changes to the user's home
directory, and establishes the user and group protections of the user.
If any of these steps fail the connection is aborted with a diagnostic
message returned.

@item
A NUL byte is returned on the initial socket and the command line is
passed to the normal login shell of the user.  The shell inherits the
network connections established by rexecd.
@end enumerate

@section Invoking

The only option is as follows:

@table @option
@item -l
@itemx --logging
@opindex -l
@opindex --logging
Raise logging level for this service; use more than once for
increased verbosity.  The @code{syslog} facility in use is
@samp{LOG_DAEMON}.

@end table

Should @command{rexecd} have been built with PAM support,
it reads any setting specified for a service named @samp{rexec}.

@section Diagnostics

Except for the last one listed below, all diagnostic messages are
returned on the initial socket, after which any network connections
are closed.  An error is indicated by a leading byte with a value of 1
(0 is returned in step 7 above upon successful completion of all the
steps prior to the command execution).

@table @samp
@item username too long
The name is longer than 16 characters.

@item password too long
The password is longer than 16 characters.

@item command too long
The command line passed exceeds the size of the argument list (as
configured into the system).

@item Login incorrect.
No password file entry for the user name existed.

@item Password incorrect.
The wrong password was supplied.

@item No remote directory.
The chdir command to the home directory failed.

@item Try again.
A fork by the server failed.

@item <shellname>: @dots{}
The user's login shell could not be started.  This message is returned
on the connection associated with the stderr, and is not ...
@c FIXME: Fill this out.
@end table

@emph{Note}, that indicating @samp{Login incorrect} as opposed to
@samp{Password incorrect} is a security breach which allows people to
probe a system for users with null passwords.

@node talkd invocation
@chapter @command{talkd}: a server for communication between users
@cindex talkd

@command{talkd} is the server that notifies a user that someone else
wants to initiate a conversation.  It acts as a repository of
invitations, responding to requests by clients wishing to rendezvous
to hold a conversation.

@example
talkd [@var{option}]@dots{}
@end example

@table @option
@item -a @var{file}
@itemx --acl=@var{file}
@opindex -a
@opindex --acl
Read site-wide ACLs from @var{file}.

@item -d
@item --debug
@opindex --debug
@opindex --d
Enable debugging.

@item -i @var{seconds}
@itemx --idle-timeout=@var{seconds}
@opindex -i
@opindex --idle-timeout
Set idle timeout value.

@item -r @var{seconds}
@itemx --request-ttl=@var{seconds}
@opindex -r
@opindex --request-ttl
Set request time-to-live value.

@item -t @var{seconds}
@item --timeout=@var{seconds}
@opindex -t
@opindex --timeout
Set timeout value.
@end table

In normal operation, a client, the caller, initiates a rendezvous by
sending a @code{CTL_MSG} to the server of type @samp{LOOK_UP} (see
@file{protocols/talkd.h}).  This causes the server to search its
invitation tables to check if an invitation currently exists for the
caller (to speak to the callee specified in the message).  If the
lookup fails, the caller then sends an @samp{ANNOUNCE} message causing
the server to broadcast an announcement on the callee's login ports
requesting contact.  When the callee responds, the local server uses
the recorded invitation to respond with the appropriate rendezvous
address and the caller and callee client programs establish a stream
connection through which the conversation takes place.

@node telnetd invocation
@chapter @command{telnetd}: Telnet server
@cindex telnetd

@example
telnetd [@var{option}]@dots{}
@end example

@table @option
@item -a AUTHMODE
@itemx --authmode=AUTHMODE
Specify what mode to use for authentication.  Allowed values are:
@samp{none}, @samp{other}, @samp{user}, @samp{valid}, and @samp{off}.

@item -D[LEVEL]
@itemx --debug=[LEVEL]
Set the debugging level.  The argument is a comma separated list of
the categories: @samp{options}, @samp{report}, @samp{netdata},
@samp{ptydata}, and @samp{auth}.  All these may be used in the form
@samp{name[=level]}.  Omission of @samp{level} implies the maximal
possible debugging for that particular category.

There is one additional category @samp{tcp}, that does not allow
the additional level indicator, but is instead equivalent to
setting the socket option @samp{SO_DEBUG} for debugging the
complete traffic.

The outcome is the file @file{/tmp/telnet.debug}, to which
data is incrementally added as time passes.

@item -E STRING
@itemx --exec-login=STRING
Set program to be executed instead of @command{/bin/login}.

@item -h
@itemx --no-hostinfo
Do not print host information before login has been completed.

@item -l[MODE]
@itemx --linemode=[MODE]
Set line mode.  An empty argument will force line mode at all times.
The only recognised value is otherwise @samp{nokludge}.

@item -n
@itemx --no-keepalive
Disable TCP keep-alives.

@item -U
@itemx --reverse-lookup
Refuse connections from addresses that cannot be mapped back into a
symbolic name.

@item -X AUTHTYPE
@itemx --disable-auth-type=AUTHTYPE
Disable the use of the given authentication type.
Use this option multiple times if more than one type
is to be disabled.  Standard choices are @samp{null},
@samp{kerberos_v4}, and @samp{kerberos_v5}.
@end table

@node uucpd invocation
@chapter @command{uucpd}: Unix to Unix Copy

Synopsis:

@example
uucpd [@var{option}]...
@end example

@node GNU Free Documentation License
@appendix GNU Free Documentation License
@include fdl-1.3.texi

@page
@node Index
@unnumbered Index

@printindex cp

@bye