The ports 6667 - 6669 and 7000 should be open.. it's more ports that mIRC using to connect to irc. the best way is to look what ports that you need to connect to your server.. pic the server you want to connect to.. then press the edit button, it should show you the ports that you can connect to.. IE: 6667-6669 <<-- that means you can use any port between that number..
