[Snort-users] a user experience w/ Snort, ACID & (Postgre|My) SQL

Matt Watchinski matt at ...1150...
Wed Oct 3 22:31:03 EDT 2001

You might want to use Merge Tables if you aren't already.  This way you
can just rotate out tables daily and then create Merges of the data you
want to deal with.  Might have to modify a few things in the db pluggin
but it should be pretty painless, and you get to keep your data around
for extended data mining


Kevin Brown wrote:
> > I am very new to Snort & practical ID though I've read like many the
> > books from Nortcutt & co. I have installed my first Snort sensors 4/5
> > weeks ago and before continuing any further, I'd like to thank Marty &
> > the crew for such a good system. I am writing this to share my
> > experience on the subject if anyone is interested. If no one gives a
> > heck about it, then sorry for the bandwidth noise :p
> >
> > Since I am working on a project for my current employer for
> > small-to-wide deployments of Snort, I choosed for my first install
> > PostgreSQL as the DB backend on an OpenBSD platform. I am not as
> > knowledgeable w/ RDBMS as I am w/ OSes in general. My OpenBSD
> > kernel is
> > as optimized as I can make it & I applied every trick I found about
> > increasing PostgreSQL performance but still, the
> > ACID/PostgreSQL couple
> > is *extremely* slow. The hardware I am using is very standard. I have
> > been in touch w/ Chris Kuethe & Roman & others about this
> > very subject,
> > read the archives ... to no avail. Looked into DNS bottlenecks, fs
> > performance ...etc. After a while, I switched the RDBMS to MySQL. Same
> > hardware, just 'mv PostgreSQL MySQL'. And the performance sky
> > rocketed.
> > Literally. While it took ages to load the ACID main page w/
> > 5000 alerts
> > w/ PostgreSQL as the backend, it showed in a snap w/ MySQL. I am
> > stumped. The system is not *that* loaded (19%sys, 34%user at
> > most & for
> > very short times) in either case. The system is not swapping (or very
> > little). But ACID/MySQL is much faster than ACID/PostgreSQL.
> >
> > Please, I do not want to start a PostgreSQL vs. MySQL flame war. I am
> > just saying that in my particular case, MySQL saves the day. The only
> > problem I am having now is w/ persistent connections & httpd gobbling
> > memory but that's another story.
> I have 1 sensor on the network here (more will be added later) that monitors
> 200Mb/s of bandwidth to the net (50Mb/s commercial, 155Mb/s I2).  Snort runs
> on a Netra T1 AC200 (500MHz Sparc IIe).  Snort connects to a remote db for
> logging through a private vlan.
> The db runs on a Quad PII450 Xeon.  We tried Mysql at first, but ran into
> problems due to the database getting large ( > 2,000,000 alerts in less than
> a month) which slowed down the inserts to mysql and as a consequence slowed
> snort down as well.  We switched to PostgreSQL and while the size of the db
> didn't seem to matter to snort any more (no performance hit of the sensor
> doing inserts), the ACID frontend was ungodly slow (4 - 8 minutes minimum to
> load any page).  Another problem that was encountered was that the portscan
> alerts were never logged with the correct time, I had some that were showing
> from the year 2041, and anytime between now and then.  Other alerts, while
> less frequently having this happen, also showed up with incorrect
> timestamps.  Both machines have their clocks synced to an NTP server every
> night, so it wasn't that the time on the machine was off, but more likely
> due to the differences between a Sun/Solaris and Intel/Linux machines.
> We have since switched back to Mysql and I have the database rotated out
> once a week to prevent it from growing too large.  Switching back also fixed
> the timestamp issues, so I can only assume that the problem is with the db
> output plugin and postgres.
> All in all this has been a good program, now if upper management would allow
> us to do something about the alerts we'd be all set.
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