General Info on UDP's, ICMP's, etc

I have just moved into a new job (a university) where I have a LAN connection. I run Win2000 & MSnetwork.I installed Tiny, Personal Firewall (pretty good) but I am having to fight my way through to understand which TCP, UDP & ICMP rquests from various nearby addresses should be permitted (local router advertisement" or some other MSnetwork type stuff. I installed a printer that wants to talk to me all the time, for example, which I block but still works. The network stops working some of the time if I block the various requests from the Local people (those with the same first three fields of the university IP address.

Is there a good website that explains what I need to allow from UDP's, ICMP's, etc, and how these work?

Thanks Dave

Some info here, or try another firewall.

http://oac3.hsc.uth.tmc.edu/staff/snewton/tcp-tutorial/index.html

Dave, just found this

http://members.rogers.com/zyklon/tpf.html

hi dave mcr,
if you want some very good info on tiny personal firewall and kerio go to dsl reports and check out their tiny and kerio forum. you'll find all the info you need on tcp, ip, udp and how to configure tpf and kerio, which by the way are the best!
cheers and good luck,
murve