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Apparmor May Block Firefox Access to Internet on Ubuntu

Firefox Troubleshooting
oceanpeaks replied 6 years ago
oceanpeaks
oceanpeaks

Good Evening, My Firefox browser on Ubuntu OS was working fine until today. The only changes I’ve made are setting up UFW (Uncomplicated Firewall) and enabling the Apparmor (provides access control for apps) profile for Firefox. Now I get the “Server Not Found” error every time I try to use Firefox.

I have tested multiple websites and they all return this error. I have also checked my firewall log and it doesn’t show any blocked connections when this is happening.

This leads me to believe that Apparmor may be blocking any/all of Firefox’s attempts to request a connection to the internet.

I have opened the Apparmor profile for Firefox in my text editor but don’t know which features are likely to be causing the problem.

Any advice would be amazing! I appreciate you volunteering your time to help the noobies out here! Please let me know if you have any questions.

Best, OceanPeaks

Good Evening, My Firefox browser on Ubuntu OS was working fine until today. The only changes I’ve made are setting up UFW (Uncomplicated Firewall) and enabling the Apparmor (provides access control for apps) profile for Firefox. Now I get the “Server Not Found” error every time I try to use Firefox. I have tested multiple websites and they all return this error. I have also checked my firewall log and it doesn’t show any blocked connections when this is happening. This leads me to believe that Apparmor may be blocking any/all of Firefox’s attempts to request a connection to the internet. I have opened the Apparmor profile for Firefox in my text editor but don’t know which features are likely to be causing the problem. Any advice would be amazing! I appreciate you volunteering your time to help the noobies out here! Please let me know if you have any questions. Best, OceanPeaks

All Replies (2)

cor-el
cor-el
  • Moderator

This could also be an issues related to DNS lookup, possibly related to using DoH (DNS over HTTPS).
You can try the DNS Lookup tool via the about:networking page.

oceanpeaks
oceanpeaks Question owner

Thank you Cor-el, I appreciate the response and resources. After going through “about:network” it became clear that Apparmor was the most likely culprit.

I put Firefox’s profile into “complain mode” (which just complains in the log if Firefox breaks a rule, rather than stopping it) and restarted the browser. This time it worked fine, so now I just need to figure out which rule(s) we’re blocking it.

I’m going to try to find the log file for Apparmor and will update this thread as more progress is made.