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Check if you need to update all your stuff - again.
(sshhole.com)
are you affected?
- is your sshd running on musl? (alpine, openwrt, buildroot, yocto)
- is it not using pam? alpine's openssh-server doesn't by default, or maybe you set UsePAM no
- are password logins still on? they are by default
- is there an account with just * as its password? key-only users, ldap users, root on alpine
- and some other account with a real password?
- then that * account takes any password between 257 and 1024 characters
on alpine's official aws and azure images that's the default alpine user, and it has passwordless doas. so it's root
on debian, ubuntu, fedora or anything else with glibc? going through pam? dropbear? openbsd? you're fine
I've been setting
UsePam = nofor decades because leaving it on meant that it'd still present a password login of keys failed. Is this still the case, was I wrong from the beginning, or is this somehow ok?I'm not following. Are you saying you login with ssh keys and not the password, but leave "UsePam = no" so then if ssh fails you don't have a pam error?
It's been years since I was experimenting, trying to set things up properly, but at the time I could swear that I'd have the following set:
and attempts to SSH into the system would still result in a password prompt, even though
PasswordAuthenticationwas set tono. After some experimentation, I found that if I setUsePamtono, you wouldn't get a password prompt, so that's what I've been doing on every SSH server I've had since like, 2000.Tinkering with it now though, I see there's also another directive,
KbdInteractiveAuthentication, which when set tono, will ensure I don't see a password prompt even whenUsePamis set toyes. I can only assume that 26ish years ago there was noKbdInteractiveAuthentication, or I just didn't know about / notice it!Well no harm done in my case anyway, as I don't generally expose SSH servers to the outside world anyway. But it's good to know that I don't have to turn off PAM to disable password logins anymore.
The way I read it, it is fine if you do not allow password authentication in general?