tracing users ip address

Running PostgreSQL 7.2.1 on RedHat Linux 7.2 kernel 2.4.7-10

I'm looking at my logs / messages and I'm trying to figure out
how to trace some users.  For example, I am trying to make
the server a bit more secure and in some of the logs I see
someone called 'Admin' trying to access the database  (and
failing ... but for how long?)

I don't know who this is, but, I'd like to know.  Is there a way
I can track down the IP address of users trying to access
the database?  I would imagine the debug that is running - currently
I'm running debug level 2 ... seems that any  higher would
slow my server down.

I don't seem to be able to see them ('Admin') using things like 'last', 'w' or
anything like that.

Suggestions?  Thank you.

-X