Hi again Jupes. Indeed it is correct that one may run more than one firewall. But i do not think that this is related as in running 2 software firewalls on 1 computer. The word firewall may consist of many different types and kinds. One of these kinds is a simple software firewall. Other kinds consist of 2 routers, a bastion Host, and a proxy server (aka application level firewalls). I think that when you read the part with 2 firewalls it was refered to a network. An example:


<your-client-with-firewall> <----> <internet>

or

<your-client-> <----> <firewall> <-----> <internet>

Where the <firewall> is a dedicated hardware firewall, or just a computer running one.

or a more complex way.

<your-client> <--> <interior-router> <--> <Bastion-Host> <--> <exterior-router> <--> <internet>

Where by the 2 routers in combination with the bastion host are 1 large firewall setup

or what i think you meant

<your-client-with-firewall> <----> <firewall> <----> <internet>


As you see there are many things called firewall. To run 2 software firewalls of one computer is nonsense. If you would like a deeper insight on firewalling (which by the way is a very good and interesting read) then i would recomend a book called "Building internet firewalls 2nd edition" by Oreilly www.oreilly.com .

Thats a great book which will cover *nix aswell as windows systems. Do not let the size or the price of the book scare you, its an excellent read.

Good luck

Cheers.