Low level control over network traffic.

[Jeff]

I need someone to point me into the right direction or suggest some
sources of information for modifying internet packets leaving and
arriving at my machine.

I'm looking to run a service my machine that will allow me to create
some sort of tunnel to another.

As an example:
Computer A is connecting to computer B with VPN.
"A" sends a packet "B" on port 998 as an example and the ISP is
blocking all traffic on 998. I need to overwrite the port in all the
packets with a destination port of 998 to something like 40000.
"B" receives a packet from "A" with a destination port of 40000 and
changes it back to 998 allowing the correct service on "B" to respond.
"B" sends a packet to "A" and a similar service on "B" will change the
origination port from 998 to 40000
"A" gets the response back from "B" and changes the origination port
from 40000 to 998

I'm looking to do this without the actual applications or services
ever knowing it took place. I'm not apposed to purchasing books and
doing my homework if I can find a good source. I have been thinking
of "Network Programming in .NET with C# and Visual Basic.net" by Fiach
Reid. Any thoughts about this book?

Thanks