Protocol Summary

AIM and ICQ are all popular instant messenger software, they both use the OSCAR protocol to communicate.

Communication

OSCAR use TCP port 5190 by default. AIM and ICQ can switch to other ports automatically, such as port 80, 443. AIM/ICQ can also connet via a SOCKS, HTTP proxy server.

How to block AIM and ICQ?

Because AIM and ICQ can switch port automatically, so you can not block them only by disable the ports in the firewall. We recommend you to block AIM/icq in two ways:

• 1). Block all AIM/ICQ server IP address.
• 2). Use firewall which has deep content inspection capabilities. Use firewall which has deep content inspection capabilities to block AIM/icq's P2P function.

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