[CentOS] saslauthd attack

B.J. McClure keepertoad at bellsouth.net
Thu Feb 11 10:33:38 UTC 2010

On Wed, 2010-02-10 at 22:33 -0500, John Hinton wrote:
> Yes... most of them. Just the new PITA. Anyway... I still can't seem to 
> figure out how to log the IP addresses for this attack.
> The system is saslauthd running as a service... sendmail and dovecot 
> setup. I have log levels in sendmail set to 14. Something has to be able 
> to log the offender(s).
> Any ideas what I'm missing or where to look?
> John
> Lincoln Zuljewic Silva wrote:
> > I supose that you are using SMTP authentication with SASL.
> >
> > >From the log "service=smtp"...so, in fact, the attack is coming from
> > the SMTP server and not directly to the SASL.
> >
> > I guess that someone is trying to do a brute force attack on the SMTP server.
> >
> > Regards
> > Lincoln
> >
> > On Wed, Feb 10, 2010 at 6:08 PM, John Hinton <webmaster at ew3d.com> wrote:
> >   
> >> I'm seeing a lot of activity over the last two days with what looks to
> >> be a kiddie script. Mostly trying to access several of our servers with
> >> the username anna. All failed... in fact I don't think we have a user
> >> anna on any of our servers. Meanwhile...
> >>
> >> I'm running Sendmail. This pertains to Centos 4 and 5 servers. I'm also
> >> running fail2ban on some and Ossec on others. So far, no blocking is
> >> being done. When I look at the logs all I find is under messages and
> >> here is a sample:

I use denyhosts which has worked well for me.  I have two IPs which have
been under attack mostly on ssh, some on dovecot, periodically for the
last six weeks.  Offending IPs are logged when blocked, but they just
switch IPs as well as login user names.

At least with denyhosts the IPs are readily available.


CentOS 5.4, Linux 2.6.18-164.11.1.el5 athlon 05:24:40 up 9:38, 1 user,
load average: 0.33, 0.17, 0.19

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