SWonder

Member
Sep 30, 2021
8
1
3
Burlington, KY
cPanel Access Level
Root Administrator
Installed nmap on my Centos8 system and got the following:

[[email protected] ~]# nmap -sU -p 53 8.8.8.8
Starting Nmap 7.70 ( Nmap: the Network Mapper - Free Security Scanner ) at 2021-10-05 18:51 UTC
Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn
Nmap done: 1 IP address (0 hosts up) scanned in 3.14 seconds

With -Pn:
[[email protected] ~]# nmap -sU -Pn -p 53 8.8.8.8
Starting Nmap 7.70 ( Nmap: the Network Mapper - Free Security Scanner ) at 2021-10-05 18:57 UTC
Nmap scan report for dns.google (8.8.8.8)
Host is up.

PORT STATE SERVICE
53/udp open|filtered domain

Nmap done: 1 IP address (1 host up) scanned in 2.09 seconds
 

cPRex

Jurassic Moderator
Staff member
Oct 19, 2014
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That second command seems like normal output to me. You may want to speak with your hosting provider if that resolvers is still not behaving as expected, since the issue would likely be outside of your server and somewhere on the network. The only other thing left to try on the server itself would be to disable the firewall temporarily while you do your testing.
 

cPRex

Jurassic Moderator
Staff member
Oct 19, 2014
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I don't have a good explanation of what would cause that since those are open to the public. It would be best to reach out to your hosting provider or datacenter to see if they can check your server and network settings to determine a root cause for the issue.