.\" @(#)identd.8 1.9 92/02/11 Lysator
.\" Copyright (c) 1992 Peter Eriksson, Lysator, Linkoping University.
.\" This software has been released into the public domain.
.\"
.\"	$Id: identd.8,v 1.4 1996/05/13 16:50:43 christos Exp $
.\"
.TH IDENTD 8 "27 May 1992"
.SH NAME
identd \- TCP/IP IDENT protocol server
.SH SYNOPSIS
.B identd
.RB [ \-i | \-w | \-b ]
.RB [ \-t<seconds> ]
.RB [ \-u<uid> ]
.RB [ \-g<gid> ]
.RB [ \-p<port> ]
.RB [ \-a<address> ]
.RB [ \-c<charset> ]
.RB [ \-n ]
.RB [ \-o ]
.RB [ \-e ]
.RB [ \-l ]
.RB [ \-V ]
.RB [ \-v ]
.RB [ \-m ]
.RB [ \-N ]
.RB [ \-d ]
.RB [ kernelfile [ kmemfile ] ]
.SH DESCRIPTION
.IX "identd daemon" "" \fLidentd\fP daemon"
.B identd
is a server which implements the
.SM TCP/IP
proposed standard
.SM IDENT
user identification protocol as specified in the
.SM RFC\s0 1413
document.
.PP
.B identd
operates by looking up specific
.SM TCP/IP
connections and returning the user name of the
process owning the connection.
.SH ARGUMENTS
The
.B -i
flag, which is the default mode, should be used when starting the
daemon from
.B inetd
with the "nowait" option in the
.B /etc/inetd.conf
file. Use of this mode will make
.B inetd
start one
.B identd
daemon for each connection request.
.PP
The
.B -w
flag should be used when starting the daemon from
.B inetd
with the "wait" option in the
.B /etc/inetd.conf
file . This is the prefered mode of
operation since that will start a copy of
.B identd
at the first connection request and then
.B identd
will handle subsequent requests
without having to do the nlist lookup in the kernel file for
every request as in the
.B -i
mode above. The
.B identd
daemon will run either forever, until a bug
makes it crash or a timeout, as specified by the
.B -t
flag, occurs.
.PP
The
.B -b
flag can be used to make the daemon run in standalone mode without
the assistance from
.B inetd.
This mode is the least prefered mode since
a bug or any other fatal condition in the server will make it terminate
and it will then have to be restarted manually. Other than that is has the
same advantage as the
.B -w
mode in that it parses the nlist only once.
.PP
The
.B -t<seconds>
option is used to specify the timeout limit. This is the number
of seconds a server started with the
.B -w
flag will wait for new connections before terminating. The server is
automatically restarted by
.B inetd
whenever a new connection is requested
if it has terminated. A suitable value for this is 120 (2 minutes), if
used. It defaults to no timeout (ie, will wait forever, or until a
fatal condition occurs in the server).
.PP
The
.B -u<uid>
option is used to specify a user id number which the
.B ident
server should
switch to after binding itself to the
.SM TCP/IP
port if using the
.B -b
mode of operation.
.PP
The
.B -g<gid>
option is used to specify a group id number which the
.B ident
server should
switch to after binding itself to the
.SM TCP/IP
port if using the
.B -b
mode of operation.
.PP
The
.B -p<port>
option is used to specify an alternative port number to bind to if using
the
.B -b
mode of operation. It can be specified by name or by number. Defaults to the
.SM IDENT
port (113).
.PP
The
.B -a<address>
option is used to specify the local address to bind the socket to if using
the
.B -b
mode of operation. Can only be specified by IP address and not by domain
name. Defaults to the 
.SM INADDR_ANY
address which normally means all local addresses.
.PP
The 
.B -V
flag makes
.B identd
display the version number and the exit.
.PP
The
.B -l
flag tells
.B identd
to use the System logging daemon
.B syslogd
for logging purposes.
.PP
The 
.B -v
flag causes
.B identd
to log every request made, if the use of
.B syslogd
is enabled.
.PP
The
.B -o
flag tells
.B identd
to not reveal the operating system type it is run on and to instead
always return "OTHER".
.PP
The
.B -e
flag tells
.B identd
to always return "UNKNOWN-ERROR" instead of the "NO-USER" or
"INVALID-PORT" errors.
.PP
The
.B -c<charset>
flags tells
.B identd
to add the optional (according to the IDENT protocol) character set
designator to the reply generated. <charset> should be a valid character
set as described in the MIME RFC in upper case characters.
.PP
The
.B -n
flags tells
.B identd
to always return user numbers instead of user names if you wish to
keep the user names a secret.
.PP
The
.B -N
flag makes
.B identd
check for a file ".noident" in each homedirectory for a user which the
daemon is about to return the user name for. It that file exists then the
daemon will give the error
.B HIDDEN-USER
instead of the normal USERID response. 
.PP
.B -m
flag makes
.B identd
use a mode of operation that will allow multiple requests to be
processed per session. Each request is specified one per line and
the responses will be returned one per line. The connection will not
be closed until the connecting part closes it's end of the line.
PLEASE NOTE THAT THIS MODE VIOLATES THE PROTOCOL SPECIFICATION AS
IT CURRENTLY STANDS.
.PP
The
.B -d
flag enables some debugging code that normally should NOT
be enabled since that breaks the protocol and may reveal information
that should not be available to outsiders.
.PP
.B kernelfile
defaults to the normally running kernel file.
.PP
.B kmemfile
defaults to the memory space of the normally running kernel.
.SH SEE ALSO
.BR inetd.conf (5)
.SH NOTES
.B Identd
uses the 
.I LOG_DAEMON
syslogd(8) facility to log messages. This is the correct thing to do
since
.I LOG_AUTH
is supposed to be used by authorization related programs, not authentication
related ones such as
.B identd.
.SH BUGS
The handling of fatal errors could be better.
.PP
If the
.B -N
flag is specified and a user's ".noident" file is not accessible,
then ident information regarding that user will be returned
if requested.