View source for Configure UFW to manage Docker related connections

==Prologue==
This guide applies to Ubuntu 20.04. After you installed docker and setup UFW to block all connections by default, docker will bypass the firewall entirely.

To fix this issue follow this guide to configure Docker and UFW to properly work together.

=== /etc/docker/daemon.json===

Start by creating/editing following file: <code>/etc/docker/daemon.json</code><syntaxhighlight lang="json">
{
"iptables": false
}
</syntaxhighlight>

=== /etc/ufw/after.rules===
Then you need to edit following file as well: <code>/etc/ufw/after.rules</code>

Make sure to paste following lines '''before''' the last line in the file which is <code>COMMIT</code>

Also adjust <code>ens3</code> to your default interface name.<syntaxhighlight lang="md">
# Put Docker behind UFW
*filter
:DOCKER-USER - [0:0]
:ufw-user-input - [0:0]

-A DOCKER-USER -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A DOCKER-USER -m conntrack --ctstate INVALID -j DROP
-A DOCKER-USER -i ens3 -j ufw-user-input
-A DOCKER-USER -i ens3 -j DROP
# End Docker UFW rules
</syntaxhighlight>Once you've done this, execute following commands to apply your changes:
{{warning}} This will restart all your docker containers.

<code>sudo systemctl restart ufw</code>

<code>sudo systemctl restart docker</code>

Test your configuration to make sure the changes are working.
[[Category:UFW]]
[[Category:Docker]]