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PORT 53 (UDP) OPEN

Dear all,

Do you know if Next DNS needs the port 53 (UDP) open in order to work properly?

In my system I have this port open and I think this is a serious security hole.

 

I have Debian 12.

 

Thanks for your help.

 

Best Regards,

JR

4 replies

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    • R_P_M
    • 2 yrs ago
    • Reported - view

    Port 53 is usually used for UDP DNS lookups.

    Are you sure port 53 is open from outside your local network? Please try using GRC Shields Up tool to check the port. 

      • R_J
      • 2 yrs ago
      • Reported - view

       

      Thanks a million for your reply !!

       

      what nmap says is the following:

      "

      PORT     STATE         SERVICE VERSION

      53/udp   open          domain  Unbound

      "

       

      As far as I know, I could only test port 53 for TCP protocol but not with UDP protocol in GRC Shields Up tool.

       

      Thanks again for your help.

       

      RJ

    • R_P_M
    • 2 yrs ago
    • Reported - view
     said:
    As far as I know, I could only test port 53 for TCP protocol but not with UDP protocol in GRC Shields Up tool.

    It doesn’t really matter if TCP or UDP, is the port open after testing with GRC Shields Up? If it reports as “stealth” then your setup is not open to connections from the internet, all is OK (for this specific port at least). 

    • R_J
    • 2 yrs ago
    • Reported - view

    Thanks a million, R P M.

    Your help is really highly appreciated.

     

    RJ

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