Latest version of Comodo firewall.
(see below) Why is Comodo (corporate) trying to communicate with Comodo (firewall software) on my laptop by sending TCP traffic on port 0?
(from my firewall logs - sanitized for my protection)
%ASA-4-500004: Invalid transport field for protocol=TCP, from 126.96.36.199/0 to 188.8.131.52/4225
According to about.com
Port 0 is officially a reserved port in TCP/IP networking, meaning that it should not be used for any TCP or UDP network communications. However, port 0 sometimes takes on a special meaning in network programming, particularly Unix socket programming. In that environment, port 0 is a programming technique for specifying system-allocated (dynamic) ports.
Configuring a new socket connection requires assigning a TCP or UDP port number. Instead of hard-coding a particular port number, or writing code that searches for an available port on the local system, network programmers can instead specify port 0 as a connection parameter. That triggers the operating system to automatically search for and return the next available port in the dynamic port number range.
Unix, Windows and other operating systems vary slightly in their handling of port 0.
it is a reserved port that should not but could be used on the web.
The IP address 184.108.40.206/0 belongs to Fastly ISP from San Francisco and 220.127.116.11 belongs to Google Australia. I guess it might be the special nature of port 0 that makes the firewall pick up this unusual traffic.