iptables -I INPUT -p tcp -m tcp --dport 1337 -j ACCEPT 

As pointed by @iain in the comments, using this on the command line will guarantee that the rule will be evaluated before the REJECT rules. If you're editing the file directly just put this before the REJECT lines:-A INPUT -p tcp -m tcp --dport 1337 -j ACCEPT

disable/enable fw
service firewalld stop/start