I’ve long been recommending clients avoid antivirus programs that include an “internet suite” such as Norton Internet Security because the included firewall software makes it very easy for the unwary to accidentally block network traffic. For most residential computer users, a router acting as a firewall tends to offer better protection with less chances of networking issues.
However, I’ve been running into a number of client who use Norton Antivirus 2006 with issues attempting to share files and printers on their local area network. The culprit, I’ve found, is NAV06’s Internet Worm Protection. This feature can mistakenly identify an incoming file or print sharing request as an attack on your computer, leading Norton to automatically block all access from that LAN IP address.
The solution I’ve found is to go into the configuration settings for the Internet Worm Protection feature and create a “Permit” rule that allows full access on ports 137, 138 and 139, which Windows uses to share files and printers on the local network.
Sometimes, a client’s protection software can be too protective.