Johannes Christian wrote:
maybe you can try using telnet to the specific port e.g $telnet server_ip 53
telnet uses TCP so that won't help for checking UDP.The reason for opening port 53 is presumably because you have a DNS server running that you want to be able to access from outside?
If so, just try doing a DNS lookup on one of the zones served by your server from outside your network:
$ dig @your.server some.hostname Paul.
