I am not sure what exactly makes the error reproducible. I encounter this error at work, on a computer with freshly installed Linux Mint 20.1 MATE.
1. install the package knockd 2. configure /etc/knockd.conf, set Interface 3. edit /etc/default/knockd to set START_KNOCKD=1 4. enable knockd.service 5. restart the system I tried at home, where I run the same system (although not freshly installed, but gradually upgraded), and knockd starts succcessfully. I also remember having a similar problem some time ago on other machines at work; at the time I solved it by placing a System V init script to /etc/network/if-up.d/. This might mean that the problem depends on the network. If it helps, I can try installing Ubuntu on a side partition at work and try it from scratch again. I suspect that maybe if the NetworkManager takes too long to bring an interface online, knockd fails. The positions of the syslog entries of NetworkManager and knockd correspond with the error happening. In comment #4 of the linked RH bug, J. Ralston claims that the After= condition is insufficient by itself if the service in question requires a dependency to be fully up and running. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1912826 Title: Knockd service fails to start due to missing dependency To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/knockd/+bug/1912826/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
