Re: periodic security run output gives false positives after 1 year

On Thu, Feb 16, 2012 at 06:04:34PM +0100, Miroslav Lachman wrote:

I see it many times before, but never take a time to post about it.

Scrips in /etc/periodic are grepping logs for yesterday date, but
without specifying year (because some logs do not have year logged).

This results in false positive alerts in security e-mails from our
lightly loaded servers, where logs are not enough rotated.

For example /var/log/auth.log is 62KB (838 lines) and contains entries
for almost 2 years.

Today I get following alert:

Feb 15 22:36:03 XXX sshd[89758]: Invalid user t1na from
Feb 15 22:50:56 XXX sshd[89850]: Invalid user medina from
Feb 15 22:50:57 XXX sshd[89852]: Invalid user student from
Feb 15 22:50:58 XXX sshd[89854]: Invalid user student from

(hostname and IP are replaced by X)

But looking in to auth.log I found zero entries from yesterday - Feb 15
entries were logged 1 year ago!

So I propose to set all daemons / syslog to log year too (as %Y) and
change yesterday=`date -v-1d "+%b %e "` to yesterday=`date -v-1d "+%b
%e %Y"` in periodic scripts.

The affected scripts are:

Maybe some others, I did just a quick grep -rsn 'date -v-1d'
/etc/periodic and I don't know the logic used in other script to get
yesterday messages.

What do you think about it?

Rotating the appropriate logs daily/weekly/monthly/whatever will silence
these false alarms.


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