I have a Centos 6 server with Ispconfig3 and a separate Netgear router. Recently after a slow internet connection I noticed hundreds of queries/connect request to port 53, in the router log, from various IPs around the world. Since this this is had happened a couple of times, I closed port 53 on the router. What I'd like to know if port 53 will impact any of the other functions on the server? Thanks
Check your named configuration if it allows recursive dns queries. If thats the case, disable dns recursion in BIND.
Found it (recursion=yes) in the named.conf file. And I see in the named.conf file under options that it listens on port #53. I'll reopen it on the router. I also bounced/restarted named. Thank, Till
