On 01/29/2015 01:47 AM, Sumit Bose wrote:
On Wed, Jan 28, 2015 at 03:11:15PM -0700, Orion Poplawski wrote:
I'm looking for some help with this problem. I'd like to have fail2ban block
systems trying to authenticate via smtp or imap. However, for known users I
get:
Jan 28 13:33:36 mail auth: pam_unix(dovecot:auth): authentication failure;
logname= uid=0 euid=0 tty=dovecot ruser=frank rhost=189.22.108.130
user=known_user
Jan 28 13:33:37 mail auth: pam_sss(dovecot:auth): authentication failure;
logname= uid=0 euid=0 tty=dovecot ruser=frank rhost=189.22.108.130
user=known_user
and for unknown users I get:
Jan 28 13:27:16 mail auth: pam_unix(dovecot:auth): authentication failure;
logname= uid=0 euid=0 tty=dovecot ruser=unknown_user rhost=189.22.108.130
so I can't key off of the pam_unix messages because that will lock out known
users, and keying off of pam_sss will only block attacks that guess a correct
username. Is there some way I can get pam_sss to log the unknown user attempts?
How does your full pam configuration looks like. E.g. on Fedora I have a
auth requisite pam_succeed_if.so uid >= 1000 quiet_success
line between pam_unix and pam_sss. Since the user is not known it will
not have a uid and not go pass this line.
auth required pam_env.so
auth sufficient pam_unix.so nullok try_first_pass
auth requisite pam_succeed_if.so uid >= 500 quiet
auth sufficient pam_sss.so use_first_pass
auth required pam_deny.so
What you say doesn't make sense to me though. As I read the docs, if
uid < 500 (as returned by pam_unix), pam_succeed_if will fail and stop
pam processing, so as to prevent authenticating system users against
sss. But if uid >= 500, it continues on to pam_sss. For unknown users
(no uid), it would seem to me that it would have to continue on to sss,
otherwise how would you authenticate users not in /etc/passwd? It just
appears to me that pam_sss is not logging attempts by unknown users, and
I'm not sure why.
--
Orion Poplawski
Technical Manager 303-415-9701 x222
NWRA/CoRA Division FAX: 303-415-9702
3380 Mitchell Lane [email protected]
Boulder, CO 80301 http://www.cora.nwra.com
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