The "sendmail-5.65c+IDA-1.4.4.1-ident.patch" file contains the modifications needed to add support of RFC931/IDENT/TAP (from now on called IDENT) in Sendmail. It uses the IDENT protocol to retrieve the identifier associated with a TCP/IP connection if someone initates a connection to the SMTP port. (And the machine the connection was initated from has a server running that implements this protocol. One such server can be FTP'd from the machine "ftp.lysator.liu.se" in the directory "pub/ident" as "pidentd-???.tar.Z". It will put the identifier retrieved into the "$F" macro so that it can be included at an apropriate place in the "sendmail.cf" configuration file. For example, we are using the following entry for the "HReceived" line: HReceived: $?sfrom $s $.by $j $?r with $r$. ($v/$Z/Lysator-3.1) id $i; $b $?F (rfc931-sender: $F@$S)$. This will add a comment line to the "Received:" line if it can retreive an identifier. The identifier will also be included in the "syslog" log file. An example of how it might look like is: Jul 29 08:17:43 lysator sendmail[10169]: AA10169: from=, size=1239, class=0, received from daemon@eff.org (192.88.144.3) This patch should work on plain Sendmail-5.65c with some small hand editing (the line numbers might now match exactly). Peter Eriksson , 30 July 1992