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Linux Device Configuration

Example Net-SNMP Configuration

This can be placed in /etc/snmp/snmpd.conf and will provide the required parameters for Observium. This example uses version 2c snmp auth.

Community string

Remember to replace community_string with your unique community string.

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#  Listen for connections on all interfaces (both IPv4 *and* IPv6)
agentAddress udp:161,udp6:[::1]:161

#  Full view access
view   all         included   .1

#  Default access to full view
rocommunity community_string  default    -V all

#  System contact and location
syslocation Rack/Room/Building, Street, City, Country [GPSX,Y]
syscontact Contact Person <your@email.address>

#  Disk Monitoring
includeAllDisks  10%

# This line allows Observium to detect the host OS if the distro script is installed
extend distro /usr/local/bin/distro

# These lines allow Observium to detect hardware, vendor and serial
# Common Linux:
extend hardware /bin/cat /sys/devices/virtual/dmi/id/product_name
extend vendor   /bin/cat /sys/devices/virtual/dmi/id/sys_vendor
extend serial   /bin/cat /sys/devices/virtual/dmi/id/product_serial

# Raspberry Pi:
#extend hardware /bin/cat /proc/device-tree/model
#extend serial   /bin/cat /proc/device-tree/serial

# This line allows Observium to collect an accurate uptime
extend uptime /bin/cat /proc/uptime

# This line enables Observium's ifAlias description injection
# Require install python package: snmp_passpersist
pass_persist .1.3.6.1.2.1.31.1.1.1.18 /usr/local/bin/ifAlias.py

Accurate Uptime

The pre-existing uptime values available via Net-SNMP are either inaccurate or will wrap after 1.5 years. To work around this we check for an entry in net-snmp's extend table for a custom uptime value.

Add this to /etc/snmp/snmpd.conf of the device being monitored and restart snmpd.

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extend uptime /bin/cat /proc/uptime

This is not required when using the Unix Agent.

Distribution Detection

Install the latest distro script on the device to be monitored:

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sudo curl -fLo /usr/local/bin/distro https://www.observium.org/files/distro
sudo chmod +x /usr/local/bin/distro

Alternatively, use wget:

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sudo wget -O /usr/local/bin/distro https://www.observium.org/files/distro
sudo chmod +x /usr/local/bin/distro

Add the following line to /etc/snmp/snmpd.conf:

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extend distro /usr/local/bin/distro

This exposes the result through the standard NET-SNMP-EXTEND-MIB. Restart the SNMP daemon after changing the configuration:

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sudo service snmpd restart

Testing

Walk the standard Net-SNMP extend tree from the Observium server:

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snmpwalk -v2c -c <community> <hostname> .1.3.6.1.4.1.8072.1.3.2

The output should include the distro value in NET-SNMP-EXTEND-MIB::nsExtendOutput1Line."distro":

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NET-SNMP-EXTEND-MIB::nsExtendOutput1Line."distro" = STRING: Linux|5.15.0-91-generic|amd64|Ubuntu|22.04.5||

Testing legacy configurations

Older installations using the prefixed extend configuration remain supported:

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extend .1.3.6.1.4.1.2021.7890.1 distro /usr/local/bin/distro

Check its exact output OID with:

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snmpget -v2c -c <community> <hostname> .1.3.6.1.4.1.2021.7890.1.3.1.1.6.100.105.115.116.114.111

For a legacy exec configuration, use:

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exec .1.3.6.1.4.1.2021.7890.1 distro /usr/local/bin/distro
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snmpget -v2c -c <community> <hostname> .1.3.6.1.4.1.2021.7890.1.101.1

Hardware/Vendor Detection

Minimum version

This feature is available beginning version 19.2.9717

Many Linux/distributions expose system hardware, vendor and serial in /sys virtual filesystem.

  1. Add these lines to the /etc/snmp/snmpd.conf to enable detection:

  2. Linux (common):

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    extend hardware /bin/cat /sys/devices/virtual/dmi/id/product_name
extend vendor   /bin/cat /sys/devices/virtual/dmi/id/sys_vendor
extend serial   /bin/cat /sys/devices/virtual/dmi/id/product_serial

  3. Raspberry Pi / Orange Pi (only):

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    extend hardware /bin/cat /proc/device-tree/model
#extend serial   /bin/cat /proc/device-tree/serial

  4. Restart the SNMP daemon!

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    sudo service snmpd restart

Existing installations using the legacy .1.3.6.1.4.1.2021.7890.2 through .1.3.6.1.4.1.2021.7890.4 prefixes continue to be supported.

Warning

In some environments snmpd won't have permissions to read /sys/devices/virtual/dmi/id/product_serial. Permissions need to be changed at boot by adding this command to /etc/rc.local

chmod 444 /sys/devices/virtual/dmi/id/product_serial

ifAlias Support

If you would like to put descriptions on your interfaces on Linux distributive, you can use the script provided in scripts/ifAlias.py

  1. Install additional (python) package:

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    sudo pip install snmp_passpersist

  2. Save it somewhere on the systems you want to return ifAliases (i.e. /usr/local/bin/ifAlias.py), then add this into your snmpd.conf:

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    pass_persist .1.3.6.1.2.1.31.1.1.1.18 /usr/local/bin/ifAlias.py

  3. Restart the SNMP daemon!

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    sudo service snmpd restart

  4. Set interface alias.

  5. Common Linux systems support ip link set alias command:

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ip link set eth0 alias "Transit: YourISP Inc. Leased Line"

  • Generic Debian/Ubuntu:

    You can put the descriptions into /etc/network/interfaces

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# eth0: Transit: YourISP Inc. Leased Line
iface eth0 inet static
  ....

for access script to /etc/frr/frr.conf you need add Debian-snmp user to frr and frrvty groups:

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```
sudo usermod -a -G frr,frrvty Debian-snmp
```

On the next poll, Observium should then pick up your descriptions. (Don't forget to restart snmpd after changing the configuration!)