I recently overhauled my router’s firewall rules. I erased everything and added minimal permissions for the ports that I need to be open. However I found that Blogger was no longer able to publish to my system’s FTP server. I was able to fix it by setting my router to allow both TCP and UDP on my FTP port, where I had previously set it to only allow TCP.
Now I’m worried that other things (like HTTP/SVN/MySQL/etc.) could be incorrectly blocked because I have everything else set block UDP—or more accurately, to only allow traffic over TCP on the specified ports.
How can I find out which protocols various web-services use? For example, if I have the router set to allow Subversion traffic on port 3690, should I allow TCP, UDP, or BOTH? What about Telnet, POP3, HTTPS, and so on?