OpenWRT and SNMP bandwidth monitor

I would appreciate it if we could monitor the bandwidth of the network devices in our wrt54gs. To do so, we need SNMP enabled on our device and some kind of application to monitor the snmp messages. I choose PRTG to monitor the SNMP messages sent.

Installing the package

We need to install the snmp daemon on OpenWrt. So, we require the following package, snmpd_5.1.2-2_mipsel.ipk. Optionally, you van install the package snmp-utils_5.1.2-2_mipsel.ipk. Since I have my router modded with the MMC/SD card mod, I am going to install the package on this card with the following command.

root@Hellhound:~# ipkg -d opt install snmpd_5.1.2-2_mipsel.ipk

In my case, this will install the package on the mount point /opt. I will refer to this in the paper. Change it to your setup accordingly.

Set up the package

Now we need to set up the snmp package. If you install it in the root of linux, there is no problem. But if you installed op your MMC/SD card you need to take some extra steps. First we have to copy the /opt/etc/default, /opt/etc/init.d and /opt/etc/snmp to the /etc directory. Now we have to copy the file /etc/init.d/snmpd to the file /etc/init.d/S60snmpd. After copying this file, we have to add 2 lines to the script. This is only needed for the ones who have installed the package on the MMC/SD-card. The new file will look like this.


export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/opt/bin:/opt/sbin:
export LD_LIBRARY_PATH=/lib:/usr/lib:/opt/lib:/opt/usr/lib


[ -f $DEFAULT ] && . $DEFAULT

case $1 in
[ -d $LIB_D ] || mkdir -p $LIB_D
[ -d $LOG_D ] || mkdir -p $LOG_D
[ -d $RUN_D ] || mkdir -p $RUN_D
snmpd $OPTIONS
[ -f $PID_F ] && kill $(cat $PID_F)
echo "usage: $0 (start|stop)"
exit 1
exit $?

You can also follow the instructions on this page. You will need the script in paragraph 4.3. So, you don’t have to follow the instructions pointed out above here. Just follow the instructions on that page in paragraph 4.3.

What’s next?

You can now reboot your router and the snmpd daemon will start automatically. Now it is time to set up a monitoring tool. I used PRTG, but there are others around. It is out of the scope of this paper to describe the use of PRTG. There is enough material around to help you on that one.