[arch-general] pam settings INSECURE

Caleb Cushing xenoterracide at gmail.com
Wed Nov 18 15:09:13 EST 2009

> As far as the people I know, passwd -d and passwd -l are the most
> common ways to do this. They do NOT change the shell. Changing the
> shell to lock out an account is laughable

expiredate would be more appropriate but again it didn't seem to be
instant. locking the password is good but it 'reportedly' won't stop
key/token authentication nor should it.

>Who said that setting the user's shell to /bin/false means disabling a user?

googling disabling a unix account often lists this and I know I've
read a few books listing this. I'm not saying it's the most correct
answer, but given that this shell only refers to a login shell if this
isn't valid why should they be able to login? we set system accounts
like postgresql to this for this reason, they aren't supposed to be
logging in. again even though this is likely largely misinformation,
it's far to common to ignore. also if you look at an account and there
shell is /(s)bin/nologin wouldn't you assume that they aren't supposed
to be able to login?

>So basically you just need to add  "auth        required
>pam_shells.so" to all pam files related to login, correct ?

mostly yes.

>Or what were the other problematic settings of pam.d/kde ?

 but I believe all of the login files should be mostly similar. the
suggestion of using common files is actually good and tweaking for the
last few modules. for example anything that provides login should also
be logging to faillog. basically unless it's medium specific they
should basically be doing the same things.

I also noticed arch hasn't changed to used pam_tally2 which I believe
is a replacement for pam_tally. I don't have much details on this

I should also say that the practices of kde-np concern me and I'm
going to review them. I assume that's the file for 'no password'? it
seems to be too permissive. it should check other stuff and just not
password. but I haven't had time to check it over yet.

Caleb Cushing


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