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DNS server

Posted: February 20th, 2021, 9:47 am
by kosta88
Hello,
can someone please explain me why is Sabnzbd forcing usage of Google DNS server to resolve usenet server? Shouldn't it use default system DNS?
Thank you

Re: DNS server

Posted: February 20th, 2021, 10:22 am
by sander
What makes you think SAB uses Google's DNS?

Re: DNS server

Posted: February 20th, 2021, 10:29 am
by kosta88
tcpdump -i docker0 dst port 53
15:38:03.090188 IP 172.17.0.2.36465 > dns.google.domain: 49882+ [1au] AAAA? news-eu.newshosting.com. (52)
15:38:08.092279 IP 172.17.0.2.49125 > dns.google.domain: 41662+ [1au] A? news-eu.newshosting.com. (52)
15:38:13.096100 IP 172.17.0.2.53754 > dns.google.domain: 41662+ [1au] A? news-eu.newshosting.com. (52)
15:38:18.100091 IP 172.17.0.2.49125 > dns.google.domain: 41662+ [1au] A? news-eu.newshosting.com. (52)
15:38:23.105187 IP 172.17.0.2.53754 > dns.google.domain: 41662+ [1au] A? news-eu.newshosting.com. (52)

And the fact that my firewall (OPNsense) reports it too. And the fact they never come in on my Pi-hole.
Docker host is set to Pi-hole.
172.17.0.2 is the SABnzbd Docker.

Re: DNS server

Posted: February 20th, 2021, 10:39 am
by sander
Ah, within docker. If you go into docker (docker excec /bin/sh), and do a host / nslookup from the CLI, ... does it use Google DNS ... ?

If so, it's a docker OS thing.

The other way around: SAB is open source and scripted ... so if it would use a Google DNS, you should be able to find it in the source code ... Did you check that?

Re: DNS server

Posted: February 20th, 2021, 10:57 am
by kosta88
Not so much a Linux guy... I an in the Docker shell, but there is no tcpdump, so not sure what further.
But, if that helps, no other containers do that.

Unfortunately, I have nothing to do with scripting or programming. I just wanted to point out, that's all, if at all someone wants to take a look at that.

Re: DNS server

Posted: February 20th, 2021, 11:58 am
by sander
Your question "can someone please explain me why is Sabnzbd forcing usage of Google DNS server to resolve usenet server?" contains a statement, so I assumed you checked it yourself before stating that.

Now it's a bit like "Have you stopped beating your wife?'. Quite hard to answer. Ah, wikipedia tells that's a Loaded Question. TIL.

Better:
Q: "Does SABnzbd force use Google DNS".
A: No

The underlying OS handles DNS requests. In case of Docker: the Docker DNS settings. You can check them yourself. Hint /etc/resolv.conf

Or ... can you ask the creator of your Docker image.

Re: DNS server

Posted: February 20th, 2021, 12:11 pm
by kosta88
Wasn't meant to be misunderstood. It was clear to me, but apparently shot in the wrong direction.
Thanks, will look into that.