Forum Discussion
mouverthewanderer
Nimbostratus
NimbostratusUDP DNS listener doesn't resolve DNS query but TCP DNS listener can
I'm using an F5 GTM R5000 Series device
I have configured the following components:
- Configured Self-IP, ensuring no Firewall block UDP and TCP port 53.
- Created data center, Server and Virtual Server (I chose a Generic host so Server and Virtual Server are the same IP addresses), the Virtual Servers are green
- Created a Pool which contains Virtual Server
- Created Wide IP and assigned Pool into
- Created both UDP and TCP DNS listener
I used the "dig" command to test directly, here are the results:
- Use only "dig", the F5 didn't resolve the query, I checked the statistic of the UDP listener and got nothing
- Use "dig" with the +tcp option, the F5 resolved the query, and each answer had one Virtual Server as I expect
Did I miss any configuration? What did I do wrong?
If using the same Self IP as the GTM listener, make sure port lockdown permits both udp and tcp 53. Also check the DNS profiles attached to both listeners for UDP and TCP to make sure they are both the same. Also check subnet mask and IP address for any typos.
- whisperer
MVP
If using the same Self IP as the GTM listener, make sure port lockdown permits both udp and tcp 53. Also check the DNS profiles attached to both listeners for UDP and TCP to make sure they are both the same. Also check subnet mask and IP address for any typos.
mouverthewandererThanks. I checked my network and it's blocking UDP port 53. Problem solved
- Paulius
mouverthewanderer Can you validate if the GTM is indeed receiving the UDP request? You should be able to use the following to validate that it is arriving at the F5.
tcpdump -ivvv 0.0 udp port 53
- mouverthewanderer
I used tcpdump on F5 OS and see that UDP packets didn't reach DNS listener IP. Thanks
