How to close DNS UDP ports?

By edelac379 ·
After reviewing a vulnerability scan on our network it seems that DNS is using some ports which are considered "dangerous". I found out that dns.exe is using tons of ports and that some of these "bad" ports are in use.

Is there a way to close these specific ports?

This conversation is currently closed to new comments.

Thread display: Collapse - | Expand +

All Answers

Collapse -

DNS Ports

by Nimmo In reply to How to close DNS UDP port ...

I don't want to sound patronizing or rude but do you know what DNS actually does? It's is pretty much one of the most important protocols on the internet these days, if you didn't use/have DNS you would spend your days typing in IP addresses to visit web sites.

DNS uses port 53 UDP but TCP port 53 does get used sometimes (some programs also use TCP 53 for all DNS queries). If you close these ports your going to get a lot of problems.

What ports were showing up on the results? You may want to take a look through this list of ports and confirm what protocol they really are if they are not on 53.

If you really do want to test and see what happens when you block these ports just block it at the firewall.

Collapse -

DNS only uses tcp/53 and udp/53

by SYNner In reply to How to close DNS UDP port ...

RFC 1035 does not specify any other port other than tcp/53 and udp/53. DNS services uses UDP/53 most of the time. If a request takes more than one packet to complete, DNS will switch to TCP. If you are seeing a DNS.exe process in your systems and it's using other ports, you may have a compromised system.

Related Discussions

Related Forums