Hypothetically, let's say I'm a network administrator running a Debian 5.0 linux box for my Internet router/gateway. Is there such a software package that exists that will automatically grab any interesting information going thru my gateway (obviously, I'd run the logging software -on- the gateway machine).
I'd like to do this without the client machines having to be modified in any way (Ie: no socks/proxies/etc).
Now if this was possible, I suppose I'd be interested in logging as much information as I can about each individual MAC address, such as websites visited, POP/IMAP email sent/read, usernames/passwords, Instant Messaging transcripts, etc.
I know I could whip something up using ngrep, etc... I'm just looking to see if there is already an all-in-one type solution, perhaps it would log information to a MySQL database or something.