The no. 300 actually augments in it all the ports needed by some low level communication protocol e.g. in my organization, I am running IPX/SPX, NetBIOS, SNMP, FTP, HTTP, Telnet etc. and the those utilized by some known Trojan Horses (As I said every time a vulnerable port is identified)
Only Windows ARP and RPC ports accounts to approx. 20, not including un-documented ports for special use only.
You can search out any Reference on Internet about Network Ports the list will give you an Idea of what I am talking about. Do not forget to search for Ports utilized by Specialized Networking Nodes . . .
firewall/ Cele 2004-03-13 18:41:28
I would really like to know what are thoes 300 ports and services behind them that are "normal" for a ordinary company. And while rest of the story does make sense (cheers!), suggestion to block only a few ports does not. If anybody thinks like that, he can spare himself from deploying a firewall at the first place!
