# Problems with DNS Configuration

**URL:** <https://community.ipfire.org/t/problems-with-dns-configuration/5574>\
**Category:** Network\
**Created:** [11 June 2021 08:32 UTC](https://community.ipfire.org/t/problems-with-dns-configuration/5574 "2021-06-11T08:32:14Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![norbeev](https://community.ipfire.org/user_avatar/community.ipfire.org/norbeev/32/13523_2.png) [@norbeev](https://community.ipfire.org/u/norbeev)\
**Post date:** [11 June 2021 08:32 UTC](https://community.ipfire.org/t/problems-with-dns-configuration/5574/1 "2021-06-11T08:32:14Z")

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Hi,

since short time a have great problems with DNS:  
Background:  
Ipfire = **IPFire 2.25 (x86\_64) - Core Update 156**  
Client-System = Linux Mint 20.x

With Firefox, my Client works ok ( I write this with that)  
But, if i want to use APT-Service to update or upgrade it fails regular.  
Only, if i go to  
“Domain Name System” in the GUI of my Ipfire and delete & create new it works like a charm.

BUT ONLY SHORT TIME

Sorry, what i’m doing wrong ?

greatings, norbeev

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**Author:** ![cfusco](https://community.ipfire.org/user_avatar/community.ipfire.org/cfusco/32/9213_2.png) [@cfusco](https://community.ipfire.org/u/cfusco)\
**Post date:** [11 June 2021 09:08 UTC](https://community.ipfire.org/t/problems-with-dns-configuration/5574/2 "2021-06-11T09:08:44Z")

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Are you blocking all DNS traffic except the one directed to your IPFire firewall? If yes, did you open the firewall access to DNS for the green/blue network? See paragraph 2 " _Block all DNS traffic except through IPFire’s DNS proxy_" (ignore paragraph 1), in particular subsection 2 " _Create permit incoming firewall rules for IPFire’s DNS server_". Some time ago this rule became necessary as by default now the firewall policy blocks the DNS traffic, including in the green network.

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**Author:** ![norbeev](https://community.ipfire.org/user_avatar/community.ipfire.org/norbeev/32/13523_2.png) [@norbeev](https://community.ipfire.org/u/norbeev)\
**Post date:** [11 June 2021 09:53 UTC](https://community.ipfire.org/t/problems-with-dns-configuration/5574/3 "2021-06-11T09:53:09Z")

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Dear cfusco, thank you f. your fast answer. I’ll check it as soon as possible.

But, by the way, why i can use Firefox at all time without problems.

Why only does 'nt work it for the apt update procedure.

Update Info: If i press the button: “Save (Speichern)” in the “Domain Name System - Menu” , then it also works at apt-get update. BUT, after maybe 2 minutes it crashes again.

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**Author:** ![jon](https://community.ipfire.org/user_avatar/community.ipfire.org/jon/32/15363_2.png) [@jon](https://community.ipfire.org/u/jon)\
**Post date:** [11 June 2021 16:53 UTC](https://community.ipfire.org/t/problems-with-dns-configuration/5574/4 "2021-06-11T16:53:57Z")

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I had an issue with `apt update` when IPS is enabled. Try disabling IPS temporarily (this is just a test).

For me there was single rule I had enabled that caused the problem. (Sorry I cannot remember the rule but I’ll keep looking for my notes!)

* * *

**EDIT** : Found it!

In an IPS rule named: **emerging-policy.rules**

Is a item called:  
**ET POLICY GNU/Linux APT User-Agent Outbound likely related to package management**

And it was blocking my `apt-get update`.

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**Author:** ![norbeev](https://community.ipfire.org/user_avatar/community.ipfire.org/norbeev/32/13523_2.png) [@norbeev](https://community.ipfire.org/u/norbeev)\
**Post date:** [14 June 2021 07:28 UTC](https://community.ipfire.org/t/problems-with-dns-configuration/5574/5 "2021-06-14T07:28:41Z")

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**Thank you** , very much, **jon**.  
You are (an expert).  
Your advice help’s perfect.  
As l see in my logs:  
**ET USER\_AGENTS PyCurl Suspicious User Agent Outbound**  
i disabled this at (IPS), too:

**emerging-user\_agents.rules**

especially for Linux-Mint Updater.

And by the way, in the rule who you are described i found more:

**ET POLICY GNU/Linux YUM User-Agent Outbound likely related to package management**

= how i think it’s important for RedHats(Centos) etc.

or maybe (what to you think)  
[especially for my wife, if i want to connect her lovely machine with my lovely firewall]:

**ET POLICY OS X Software Update Request Outbound**

Bye.