identd operates by looking up specific TCP/IP connections and returning the user name of the process owning the connection.
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 is 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 (ie, 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 the 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 -n flags 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 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.
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.
kernelfile defaults to the normally running kernel file.
kmemfile defaults to the memory space of the normally running kernel.
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).