After thinking about this for a while, I think the best solution is simply to remove the shell check unconditionally. I'm not sure if anyone else except me ever wanted it (and I can live with a couple of unnecessary users getting mailboxes). Done for v2.2: http://hg.dovecot.org/dovecot-2.2/rev/4eea2224e16b
I did also wonder about using a special "dovecot-skip" GECOS field for this, but maybe not a good idea either.
On 1.2.2013, at 0.35, Ben Morrow ben@morrow.me.uk wrote:
I am running Dovecot with system users (userdb passwd), but some of those users don't have shell accounts on the IMAP server so their shell on that machine is set to /usr/sbin/nologin. Currently I am using maildirs and this is not a problem, but I am in the process of switching to dbox which means I will need a cronjob running 'doveadm purge -A'.
During testing I found that those users with a 'nologin' shell are not included in the list returned by the userdb iterator, and that the iterator doesn't honour the first/last_valid_uid settings. This inconsistency seems undesirable, so the attached patch
- makes lookup perform the same checks as iteration,
- makes the 'nologin' check configurable,
- adds a new optional check that the user owns their home directory.
The last check was the one performed by qmail, and seems to me to be a more reliable 'is this a real user' check than a nologin shell.
If this patch is applied, the release notes for the next release should probably mention that system users with a 'nologin' shell will no longer be allowed to log in to IMAP until the 'auth_check_nologin' setting is changed from true to false.
Also, there seem to be two first/last_valid_uid settings: first_valid_uid itself, which is honoured by the storage subsystem, and auth_first_valid_uid, which is honoured by the 'passwd' userdb. Is this intentional?
Ben