UFW, Uncomplicated Firewall, was created for Ubuntu, then ported to other distributions as well, primarily to Debian. So, it’s no wonder, there are some incompatibilities when running UFW under Debian, at times. Those incompatibilities or errors are usually fixed in the stable releases. However, due to the difference between how things work and how we expect things to work, there may be some errors with the default configuration.
In Debian 7, UFW was installed lately. And, in the end of deploying it, the following command was run…
sudo ufw --force enable
Immediately, it provided the following error…
ERROR: problem running ufw-init
Upon digging through the issue, I noticed that IPv6 address wasn’t available in that server and UFW meant to complain about it. So, the solution is to disable IPv6 in UFW, by editing
and then comment out the line