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IDENTD(8)										IDENTD(8)

NAME
       identd, in.identd - TCP/IP IDENT protocol server

SYNOPSIS
       /usr/libexec/[in.]identd   [-i|-w|-b]   [-t<seconds>]   [-u<uid>]   [-g<gid>]   [-p<port>]
       [-a<address>] [-c<charset>] [-C[<keyfile>]] [-o] [-e] [-l] [-V] [-m]  [-N]  [-d]  [-F<for-
       mat>] [kernelfile[kmemfile]]

DESCRIPTION
       identd is a server which implements the TCP/IP proposed standard IDENT user identification
       protocol as specified in the RFC 1413 document.

       identd operates by looking up specific TCP/IP connections and returning the user  name  of
       the  process owning the connection.  It can optionally return other information instead of
       a user name.

ARGUMENTS
       The -i flag, which is the default mode, should be used when starting the daemon from inetd
       with  the  "nowait"  option  in the /etc/inetd.conf file. Use of this mode will make inetd
       start one identd daemon for each connection request.

       The -w flag should be used when starting the daemon from inetd with the "wait"  option  in
       the  /etc/inetd.conf file . This is the prefered mode of operation since that will start a
       copy of identd at the first connection request and  then  identd  will  handle  subsequent
       requests  without having to do the nlist lookup in the kernel file for every request as in
       the -i mode above. The identd daemon will run either forever, until a bug makes	it  crash
       or a timeout, as specified by the -t flag, occurs.

       The  -b	flag can be used to make the daemon run in standalone mode without the assistance
       from 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 it has the same advantage as the -w mode in that it parses the nlist only once.

       The -t<seconds> option is used to specify the timeout limit. This is the number of seconds
       a  server  started  with the -w flag will wait for new connections before terminating. The
       server is automatically restarted by 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 (i.e. will wait forever, or until a fatal condition occurs in the server).

       The -u<uid> option is used to specify a user id	number	which  the  ident  server  should
       switch to after binding itself to the TCP/IP port if using the -b mode of operation.

       The  -g<gid>  option  is  used  to specify a group id number which the ident server should
       switch to after binding itself to the TCP/IP port if using the -b mode of operation.

       The -p<port> option is used to specify an alternative port number to bind to if using  the
       -b mode of operation. It can be specified by name or by number. Defaults to the IDENT port(113).

       The -a<address> option is used to specify the local address to bind the socket to if using
       the  -b	mode  of  operation.  Can only be specified by IP address and not by domain name.
       Defaults to the INADDR_ANY address which normally means all local addresses.

       The -V flag makes identd display the version number and then exit.

       The -l flag tells identd to use the System logging daemon syslogd for logging purposes.

       The -o flag tells identd to not reveal the operating system type  it  is  run  on  and  to
       instead always return "OTHER".

       The  -e	flag  tells  identd  to always return "UNKNOWN-ERROR" instead of the "NO-USER" or
       "INVALID-PORT" errors.

       The -c<charset> flags tells 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.

       The -C[<keyfile>] option tells identd to return encrypted tokens instead  of  user  names.
       The  local  and	remote	IP addresses and TCP port numbers, the local user's uid number, a
       timestamp, a random number, and a checksum, are all encrypted using DES with a secret  key
       derived	from  the  first line of the keyfile (using des_string_to_key(3)).  The encrypted
       binary information is then encoded in a	base64	string	(32  characters  in  length)  and
       enclosed  in  square brackets to produce a token that is transmitted to the remote client.
       The encrypted token can later be decrypted by idecrypt(8).   There  may	not  be  a  space
       between	the -C and the name of the keyfile.  If the keyfile is not specified, it defaults
       to /etc/identd.key.

       The -n flag tells identd to always return user numbers instead of user names if	you  wish
       to  keep the user names a secret.  The -N flag makes 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 HIDDEN-USER instead of the normal
       USERID response.

       -m flag makes identd use a mode of operation that will allow multiple requests to be  pro-
       cessed  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.

       The -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.

       The  -F<format>	option makes identd use the specified format to display info. The allowed
       format specifiers are:
	    %u	 print user name
	    %U	 print user number
	    %g	 print (primary) group name
	    %G	 print (primary) group number
	    %l	 print list of all groups by name
	    %L	 print list of all groups by number
	    %p	 print process ID of running process
	    %c	 print command name
	    %C	 print command and arguments
       The lists of groups (%l, %L) are comma-separated, and start with the primary  group  which
       is  not	repeated.  The %p and the %c and %C formats are not supported on all architecture
       implementations (printing 0 or empty string instead).
       Any other characters (preceded by %, and those not preceded by it) are printed  literally.
       The "default" format is %u, and you should not use anything else without the -o flag.
       Not implemented yet, but on my wish-list are the following:
	    %w	 print working (current) directory
	    %h	 print home (login, naming) directory
	    %e	 print the environment

       kernelfile defaults to the normally running kernel file.

       kmemfile defaults to the memory space of the normally running kernel.

UNDOCUMENTED FLAGS
       The  -v	flag  enables more verbose output or messages. (Further occurences of the -v flag
       make things even more verbose.) Currently not used: ignored.

       The -f<config-file> option causes identd to use the named  config  file	(instead  of  the
       default /etc/identd.conf ?).  Currently not used: ignored, no config files are used.

       The -r<indirect_host> option is used in some way (for proxy queries?).

       The -C<keyfile> option is used in some way for DES encryption.

INSTALLATION
       identd  is  invoked either by the internet server (see inetd(8C) ) for requests to connect
       to the IDENT port as indicated by the /etc/services file (see services(5) ) when using the
       -w or -i modes of operation or started manually by using the -b mode of operation.

EXAMPLES
       Assuming the server is located in /usr/etc/in.identd one can put either:

       ident stream tcp wait sys /usr/etc/in.identd in.identd -w -t120

       or:

       ident stream tcp nowait sys /usr/etc/in.identd in.identd -i

       into the /etc/inetd.conf file. User "sys" should have enough rights to READ the kernel but
       NOT to write to it.

       To start it using the -b mode of  operation  one  can  put  a  line  like  this	into  the
       /etc/rc.local file:

       /usr/etc/in.identd -b -u2 -g2

       This  will  make  it run in the background as user 2, group 2 (user "sys", group "kmem" on
       SunOS 4.1.1).

NOTES
       The username (or UID) returned ought to be the login name. However it (probably, for  most
       architecture  implementations)  is the "real user ID" as stored with the process; there is
       no provision for returning the "effective user ID". Thus the UID returned may be different
       from  the login name for setuid programs (or those running as root) which done a setuid(3)
       call and their children. For example, it may (should?) be wrong for an incoming ftpd ; and
       we  are	probably  interested in the running shell, not the telnetd for an incoming telnet
       session. (But of course identd returns info for outgoing connections, not incoming ones.)

       The group or list of groups returned (with  the	-F  option)  are  as  looked  up  in  the
       /etc/passwd  and  /etc/group  files,  based on the UID returned. Thus these may not relate
       well to the group(s) of the running process for setuid or setgid programs or  their  chil-
       dren.

       The  command  names returned with formats %c and %C may be different, use one or the other
       or both.

FILES
       /etc/identd.conf
	      This file is as yet un-used, but will eventually contain configuration options  for
	      identd

       /etc/identd.key
	      If compiled with -ldes this file can be used to specify a secret key for encrypting
	      replies.

SEE ALSO
       authuser(3) , inetd.conf(5) , idecrypt(8)

BUGS
       The handling of fatal errors could be better.

					   27 May 1992					IDENTD(8)
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