Monitor Linux with SNMPv3 and PRTG

Recently I’ve been focusing on something I’ve overlooked for too long- monitoring. I wanted to share a quick guide on monitoring Debian / Ubuntu with SNMPv3 and PRTG as I couldn’t find any high level, up-to-date information readily available. I’ve gone as lightweight as possible and only installed snmpd to get disk space, CPU and memory monitoring working.

On the Debian / Ubuntu device you would like to monitor-

Update repositories

sudo apt-get update

Install snmpd

sudo apt-get install snmpd

Stop the snmpd service

sudo systemctl stop snmpd

Create credentials for SNMPv3 authentication

sudo nano /var/lib/snmp/snmpd.conf

Add the following line beneath the comment block at the top. Replace USERNAME, PASSWORD and ENCRYPTIONKEY with your values. Note the encryption key, which is simply a string shared with client and server

createUser USERNAME SHA PASSWORD AES ENCRYPTIONKEY

Edit the snmpd conf file

nano /etc/snmp/snmpd.conf

Comment out the following line-

agentAddress  udp:127.0.0.1:161

Like so-

#agentAddress  udp:127.0.0.1:161

Add the following line to allow remote access from our PRTG server-

agentAddress  udp:161

And the following line to grant read only access to the user we created earlier-

rouser   USERNAME    priv

Save and close the file.

Start the snmpd service

sudo systemctl start snmpd

Over on the PRTG server, add a device

Add the IP address of the Linux device we were just working on

Add credentials, matching what was created on the Linux device previously

Select the device created, then Add Sensor

Narrow down sensors by selecting Linux/MacOS and SNMP then select the required sensor.

Give PRTG around a minute to collect data, then the sensor will be visible from the dashboard