log data passed in outgoing connections

Hi!
I run a dedicated FreeBSD server with root access.
Some programs working on this server
establish outgoing connections to other web servers.
I need to see what data exactly they send out and probably log this info.
Preferrably some free software that would transparently log this stuff
without making problems to the server or breaking connections.
Or maybe I can just configure some firewall or smth...
Any advice welcome!

Load snort, configure your own ruleset -- easy to write -- to capture and log said data.

http://www.snort.org

Cheers.
(Yes, it is technically an IDS, but can be used for exactly the purpose you intend. )

ye maybe snort would be ok, but I just came across a simple tool - tcpflow, that does exactly what I need and the syntax is same as for tcpdump. Those who have same problem will love it!