A. There was a recent well-known problem that a telnet client could connect to an NT machine on port 135, type 10 characters and it would hang NT. There is no simple way to protect NT from a certain port attack. It is possible to configure NT to only accept incoming packets from a set of configured ports, however you have to name the ports you want to accept input from:
- From Control Panel, Double click on Network
- Click the Protocols tab
- Select TCP/IP and click Properties
- Click Advanced (bottom right)
- Check the "Enable Security" and click configure
- For TCP select "Permit Only" and enable only the ports you want to work (e.g. Web Browser is 80, FTP 21)
- Reboot NT
To protect against the port 135 attack, install the RPC hotfix for Service Pack 2.
Service Pack 3 and some its Hotfixes are also highly desirable, and address a number of Internet attack methods.