The differentiating factor is source port. A socket is made of four parts Source IP, Source Port, Destination IP, Destination port so this combination needs to be unique, rather than any particular part. This socket is a feature of UDP and TCP so they can be handled this way. This also shows the problems of proxying ICMP services although some ICMP services allow an identifier field that lets a firewall keep track of ingoing versus outgoing packets (echo and echo response).
To: [EMAIL PROTECTED] cc: (bcc: Bill Royds/HullOttawa/PCH/CA) Subject: Multiple Clients Hi All experts, I wanna know the mechanism by which firewall differentiate multiple clients under same IP. Let consider the scenario where multiple PCs are connected to the net via the same firewall. All PCs use the same IP proxy to access the internet. Let's say a few users are voice chatting on internet. All are using same listening port for RTP. Here what I am confused about is how does a firewall or proxy differentiate between each client, since packets will come on the same port and same IP for all internal users. Does firewall/proxy multicast all the packets that arrive onto that particular listen port in its LAN ? Or is it a different mechanism ? I will highly appreciate your reply. Thanks in advance, Ram Prasad __________________________________________________ Do You Yahoo!? Make a great connection at Yahoo! Personals. http://personals.yahoo.com _______________________________________________ Firewalls mailing list [EMAIL PROTECTED] http://lists.gnac.net/mailman/listinfo/firewalls _______________________________________________ Firewalls mailing list [EMAIL PROTECTED] http://lists.gnac.net/mailman/listinfo/firewalls
