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Graphing packet traffic with pf & pfstat

by on Dec.21, 2005, under Networking, OpenBSD

Getting a good visual representation of your network traffic has never been easier. We use OpenBSD for most of our firewalling applications, and for VoIP/VPN solutions. As a result, we (as well as our customers) need to closely track the bandwidth utilization of some of the endpoints for quality of (VoIP) service reasons. RRDTool and MRTG are both very excellent tools, but what to do when snmp is not an option? Pfstat, available in the OpenBSD ports tree, solves this problem, and is *considerably* easier to install and configure.
First, install pfstat.
$ cd /usr/ports/net/pfstat
$ sudo make install

Now, set it up.
you need to create a few files first.
$ sudo touch /var/log/pfstat
$ sudo touch /etc/pfstat.conf

Now, set up the /etc/pfstat.conf file you just created.
$ sudo vi /etc/pfstat.conf

Here’s an example pfstat.conf I found on benzedrine.cx, (the homepage of the author of pf & pfstat) and modified just slightly.
Thank you, Mr. Hartmeier. Your work is amazing.

Speaking of Pf, we need to edit the packet filter configuration, to set the log interfaces.
$ sudo vi /etc/pf.conf

Now, find your interface names. (Mine are $ext_if=rl0 and $int_if=fxp0)
So, I added the following lines to the /etc/pf.conf
set loginterface rl0
set loginterface fxp0
(It has been pointed out that this is incorrect.
The last interface listed is the one that will get used. Thanks, Jon.)

Fetch the new packet filter configuration:
$ sudo pfctl -f /etc/pf.conf
Now, edit root’s crontab to run pfstat and update your graphs.
$ sudo su
# crontab -e -u root

and add the following two lines to it:
* * * * * /usr/local/bin/pfstat -q >>/var/log/pfstat
*/5 * * * * /usr/local/bin/pfstat -c /etc/pfstat.conf -d /var/log/pfstat >/dev/null

Hold “Shift” and hit “ZZ” to save and exit root’s crontab.
To force the creation of the graph images, run this:
$ sudo /usr/local/bin/pfstat -q >>/var/log/pfstat
$ sudo /usr/local/bin/pfstat -c /etc/pfstat.conf -d /var/log/pfstat >/dev/null

Now, you just need an HTML document to display your nifty new graphs.
Here’s the one I use.
Save it to /var/www/htdocs/traffic_stats.html, and start up apache:
$ sudo apachectl start

and check out your traffic:
http://your.web.server/traffic_stats.html

.


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