On a ubuntu 21.10, using docker as a snap (snap install docker). With my firewall enabled, i have a problem resolving DNS:
$ docker run bash ping www.google.com
==> error
$ docker run bash ping 8.8.8.8
==> ok
If I disable the firewall, all is ok (sudo ufw disable):
$ docker run bash ping www.google.com
==> ok
My ufw status is like:
Status: active
To Action From -- ------ ---- 22/tcp ALLOW Anywhere OpenSSH
ALLOW Anywhere Samba
ALLOW 192.168.100.0/24 22/tcp (v6)
ALLOW Anywhere (v6) OpenSSH (v6)
ALLOW Anywhere (v6)
I suspect that the docker container has no access to the internet over TCP (and probably UDP).
What would be the correct config to use to allow docker/snap to pass through the firewall?