from the old FAQ:
How do I disable the rule that forbids portforwarding on port 81?
You will need to do two things to avoid port conflicts.
First choose a new port that you want to let the IPCop interface listen on. Do not choose 8080, 800 or 80 as squid is listening on 800 and if you have DansGuardian installed, it listens on 8080 and port 80 is used by webservers.
You need to edit the /etc/httpd/conf/httpd.conf file, search for all instances of 81 and replace with your new port. Once you have done that, save your work and we need to restart the web server with the following command:
killall httpd
httpd -DSSL
Next we need to adjust the port forward page to allow you to forward port 81, but restrict a forward on your new port.
Edit /home/httpd/cgi-bin/portfw.cgi
Find line that looks like this:
my @tcp_reserved = (81,222,445);
Change the 81 to the port number that you previously chose.
Save the changes.
You can now port forward on port 81.
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