-.\" Hey Emacs! This file is -*- nroff -*- source.
-.\"
.\" This manpage is Copyright (C) 1996 Austin Donnelly <and1000@cam.ac.uk>,
.\" with additional material Copyright (c) 1995 Martin Schulze
.\" <joey@infodrom.north.de>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" This manpage was made by merging two independently written manpages,
.\" one written by Martin Schulze (18 Oct 95), the other written by
.\" Thu Jan 11 12:14:41 1996 Austin Donnelly <and1000@cam.ac.uk>
.\" * Merged two services(5) manpages
.\"
-.TH SERVICES 5 1996-01-11 "Linux" "Linux Programmer's Manual"
+.TH SERVICES 5 2010-05-22 "Linux" "Linux Programmer's Manual"
.SH NAME
services \- Internet network services list
.SH DESCRIPTION
and
.BR endservent (3)
support querying this file from programs.
-
+.PP
Port numbers are assigned by the IANA (Internet Assigned Numbers
Authority), and their current policy is to assign both TCP and UDP
protocols when assigning a port number.
Therefore, most entries will
have two entries, even for TCP-only services.
-
-Port numbers below 1024 (so-called "low numbered" ports) can only be
-bound to by root (see
+.PP
+Port numbers below 1024 (so-called "low numbered" ports) can be
+bound to only by root (see
.BR bind (2),
.BR tcp (7),
and
and not a rogue service run by a user of the machine.
Well-known port numbers specified by the IANA are normally
located in this root-only space.
-
+.PP
The presence of an entry for a service in the
.B services
file does not necessarily mean that the service is currently running
.BR inetd.conf (5).
In particular, news (NNTP) and mail (SMTP) servers are often
initialized from the system boot scripts.
-
+.PP
The location of the
.B services
file is defined by
.IR <netdb.h> "."
This is usually set to
.IR /etc/services "."
-
+.PP
Each line describes one service, and is of the form:
.IP
\f2service-name\ \ \ port\f3/\f2protocol\ \ \ \f1[\f2aliases ...\f1]
.TP
.I aliases
is an optional space or tab separated list of other names for this
-service (but see the BUGS section below).
+service.
Again, the names are case
sensitive.
.PP
Either spaces or tabs may be used to separate the fields.
-
+.PP
Comments are started by the hash sign (#) and continue until the end
of the line.
Blank lines are skipped.
-
+.PP
The
.I service-name
should begin in the first column of the file, since leading spaces are
can be any printable characters excluding space and tab.
However, a conservative choice of characters should be used to minimize
compatibility problems.
-E.g., a\-z, 0\-9, and hyphen (\-) would seem a
+For example, a\-z, 0\-9, and hyphen (\-) would seem a
sensible choice.
-
+.PP
Lines not matching this format should not be present in the
file.
(Currently, they are silently skipped by
and
.BR getservbyport (3).
However, this behavior should not be relied on.)
-
-As a backwards compatibility feature, the slash (/) between the
-.I port
-number and
-.I protocol
-name can in fact be either a slash or a comma (,).
-Use of the comma in
-modern installations is deprecated.
-
+.PP
+.\" The following is not true as at glibc 2.8 (a line with a comma is
+.\" ignored by getservent()); it's not clear if/when it was ever true.
+.\" As a backward compatibility feature, the slash (/) between the
+.\" .I port
+.\" number and
+.\" .I protocol
+.\" name can in fact be either a slash or a comma (,).
+.\" Use of the comma in
+.\" modern installations is deprecated.
+.\"
This file might be distributed over a network using a network-wide
naming service like Yellow Pages/NIS or BIND/Hesiod.
-
+.PP
A sample
.B services
file might look like this:
-.RS
-.nf
-.sp
-.ta 3i
+.PP
+.in +4n
+.EX
netstat 15/tcp
qotd 17/tcp quote
msp 18/tcp # message send protocol
ftp 21/tcp
# 22 \- unassigned
telnet 23/tcp
-.fi
-.RE
+.EE
+.in
.SH FILES
.TP
.I /etc/services
.\" There is a maximum of 35 aliases, due to the way the
.\" .BR getservent (3)
.\" code is written.
-.\"
+.\"
.\" It's not clear when/if the following was ever true;
.\" it isn't true for glibc 2.8:
.\" Lines longer than
.\" and
.\" .BR getservbyport (3).
.\" However, this will also cause the next line to be mis-parsed.
-.SH "SEE ALSO"
+.SH SEE ALSO
.BR listen (2),
.BR endservent (3),
.BR getservbyname (3),
.BR inetd.conf (5),
.BR protocols (5),
.BR inetd (8)
-
-Assigned Numbers RFC, most recently RFC\ 1700, (AKA STD0002)
+.PP
+Assigned Numbers RFC, most recently RFC\ 1700, (AKA STD0002).
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