Does anyone know of an online tutorial to help understanding of
firewall rules and configurations as well as standard rules for
assigning individual port control and filtering based on geenral
application use?
eg application A may access trusted network, but not internet; or may
access both trusted network and internet but allow neither server
permissions etc etc

Problem here is internal network works without internet access
normally, however, each box on the network needs to be able to access
internet using dial up from time to time, unpredictably.

Not being high speed through a NAT router for internet access, and too
costly to dedicate an extra phone line and a single box to use packet
forwarding and IP masquerading through an always on dial up
connection, the need for software firewall/packet filter on each box
always is obvious.

Any suggestions would be greatly appreciated.