Internet through company firewall to my workstation

DonnieBrasco

Hi,

I'm writing a small application that uses Winsock.

To keep things simple, lets just say its a chat program like ms messenger.

Can someone tell me how msn messenger is able to get through the company firewall - and route the reply message back to my workstation...my local lan ip address...1 local lan ip address out of hundreds.

for example, if i send a message to my mate... who's out on the web some where, he can reply and i get the message.
how does messenger manage to route the message back through to the firewall to my lan ip address ?

if i wanted to run a webserver on my workstation, i have to get the IS dude to use port forwarding... so, from the firewall it forwards stuff to my webserver, but with msn messenger, this isnt necessary????

Cheers

TimTim

Afaik its because a webserver needs a open incoming port while MSN doesn't.

It opens a outgoing port and due to the magic of NAT/your firewall/whatever you use when it gets a reply it knows pc x has a connection on this port and then forwards it back to your machine.

DonnieBrasco

ah sheeet. i dont suppose i'd be able to do that with winsock.

i might try the programming forum to see if anything similar has been posted.

cheers,