HowTo: Monitor network traffic with vnStat on FreeBSD

vnStat is a console-based network traffic monitor. It keeps a log of
hourly, daily and monthly network traffic for the selected interface(s).

Bellow you'll find the needed steps for its installation and setup on FreeBSD 7.0:

1. % su
2. # cd /usr/ports/net/vnstat ; make install clean
   
3. # rehash
4. # ifconfig -a
5. # vnstat -u -i rl0
6. # cat /usr/local/share/doc/vnstat/vnstat-cron >> /etc/crontab

On steps 1 to 3 we basically became to the superuser, changed to the vnStat's port directory, proceeded by compiling the port and rehashing the shell.

Step 4 purpose is to find out the system network interface(s) in use, which in my case is rl0.

Finally with step 6 we've activated the cron job to feed vnStat's database following the port's supplied example.

To display the default statistics:

• % vnstat

To display daily traffic statistics use the -d switch:

• % vnstat -d

Monthly traffic statistics can be viewed with the -m switch:

• % vnstat -m

To display current transfer rate for the selected interface in real time until interrupted:

• % vnstat -l -i rl0
  

A nice list of switches can be viewed typing the following command:

• % vnstat --help
  

And we're done. ;)

Further documentation is available at http://humdi.net/vnstat/.