On 9/4/23 1:41 PM, TWHG Technical via dovecot wrote:
Sep 04 10:45:29 ourdomain dovecot[63336]: ^[[0;1;31m^[[0;1;39m^[[0;1;31mmaster: Error: service(imap-login): listen(::, 143) failed: A> Sep 04 10:45:29 ourdomain dovecot[63336]: Error: socket() failed: Address family not supported by protocol Sep 04 10:45:29 ourdomain dovecot[63336]: Error: service(imap-login): listen(::, 993) failed: Address family not supported by protocol Sep 04 10:45:29 ourdomain dovecot[63336]: ^[[0;1;31m^[[0;1;39m^[[0;1;31mmaster: Error: socket() failed: Address family not supported > Sep 04 10:45:29 ourdomain dovecot[63336]: ^[[0;1;31m^[[0;1;39m^[[0;1;31mmaster: Error: service(imap-login): listen(::, 993) failed: A> Sep 04 10:45:29 ourdomain dovecot[63336]: Fatal: Failed to start listeners Sep 04 10:45:29 ourdomain dovecot[63336]: ^[[0;1;31m^[[0;1;39m^[[0;1;31mmaster: Fatal: Failed to start listeners^[[0m Sep 04 10:45:29 ourdomain systemd[1]: ^[[0;1;39m^[[0;1;31m^[[0;1;39mdovecot.service: Main process exited, code=exited, status=89/n/a^> Sep 04 10:45:29 ourdomain systemd[1]: ^[[0;1;38;5;185m^[[0;1;39m^[[0;1;38;5;185mdovecot.service: Failed with result 'exit-code'.^[[0m Sep 04 10:45:29 ourdomain systemd[1]: ^[[0;1;31m^[[0;1;39m^[[0;1;31mFailed to start Dovecot IMAP/POP3 email server.^[[0m dpkg: error processing package dovecot-core (--configure):
I can understand why you dislike the cascade of failure messages. I dislike them as well. Of course, I've been following the RFCs for longer than I can remember, as well as doing network programming in the C language, among others, so I recognize "Address family not supported" for the error message that it is.
Here's a pro tip: your concern is about security...so use security tools to implement what you want. For Ubuntu, that's the ufw(8) firewall system. (Other distributions use other utilities, like iptables(8), but that's beside the point.)
Want to lock out IPv6? Do it with ufw firewall settings. That would cause the least amount of breakage. More stuff will work out of the box using the firewall to block ne'er-do-wells.
I'll also speak as a long-time software developer: you HAVE to make assumptions about the underlying system in order to stay sane, let alone concentrate on making the software perform its function correctly. In the Unix environment, particularly in shell scripts, you depend on certain binaries being available. It's bad enough trying to design software to run in different distributions or even operating environments (Linux v Unix v Mac v Windows) without having to second-guess administrators who remove tools willy-nilly.
The above should be part of System Administration 101. Which I never took, but had to learn in the school of hard knocks. And I do know that the certification bodies don't test for that particular nugget. Which is why we have mailing lists to help people with sore toes.