Cannot connect to the Internet after installing a Symantec security product

Situation:

You have problems connecting to your Internet Service Provider (ISP) over a cable modem or DSL connection after installing a Symantec security product.

Explanation:

Certain ISPs periodically scan multiple ports on computers using their service. The personal firewall included in your Symantec security product detects the port scan and activates AutoBlock, which automatically blocks all incoming traffic from the IP address of the ISP computer for 30 minutes. A security scan check from a site such as Symantec Security Check will also cause AutoBlock to block incoming traffic from the IP address. The result is that your computer is not able to access the Internet for 30 minutes.

Solution:

To resolve this problem, add the IP address of computer your ISP uses to scan ports to your AutoBlock exclusion list.

To add an IP address to your AutoBlock exclusion list:

  1. Open your Symantec security product.
  2. Click Intrusion Detection.
  3. Click Configure.
  4. In the AutoBlock section of the window, identify the IP address of the computer your ISP uses for portscans.
    If more than one IP address is in the AutoBlock list, consult your ISP to identify the IP address you should use.
  5. Click the IP Address button.



  6. In the Exclusions window, select your ISP's IP address.
  7. Click Exclude>> to move the IP address moves to the Excluded Computers list.
  8. Click OK.

Note: Adding a computer to the IP Exclusion list does not allow unauthorized access to your computer or negatively affect your computer's security. This procedure simply prevents that computer from being added to the AutoBlock list.