Paperback 
Install an SNMP Agent and Configure Telegraf SNMP Input
Video Lecture
Description
SNMP stands for Simple Network Management Protocol.
We can configure Telegraf to read SNMP, save it into InfluxDB and view it in Grafana.
Common devices that support SNMP are routers, switches, printers, servers, workstations and other devices found on IP networks.
Not every network device supports SNMP, or has it enabled, and there is a good chance you don't have an SNMP enabled device available that you can use in this section.
So, I will show you how to install SNMP on an Ubuntu 20.04 server.
I will install it locally on the same server running InfluxDB.
sudo apt install snmp snmpd snmp-mibs-downloader
It is normally running after install.
sudo service snmpd status
Individual commands to either start, stop or restart are,
sudo service snmpd start
sudo service snmpd stop
sudo service snmpd restart
Do a test query
snmpwalk -v 2c -c public 127.0.0.1 .
The response should show results with OID numbers like in this example output
iso.3.6.1.2.1.1.1.0 = STRING: "Linux grafana 4.15.0-72-generic #81-Ubuntu SMP Tue Nov 26 12:20:02 UTC 2019 x86_64"
iso.3.6.1.2.1.1.2.0 = OID: iso.3.6.1.4.1.8072.3.2.10
iso.3.6.1.2.1.1.3.0 = Timeticks: (443) 0:00:04.43
iso.3.6.1.2.1.1.4.0 = STRING: "Me <me@example.org>"
iso.3.6.1.2.1.1.5.0 = STRING: "grafana"
iso.3.6.1.2.1.1.6.0 = STRING: "Sitting on the Dock of the Bay"
iso.3.6.1.2.1.1.7.0 = INTEGER: 72
iso.3.6.1.2.1.1.8.0 = Timeticks: (11) 0:00:00.11
iso.3.6.1.2.1.1.9.1.2.1 = OID: iso.3.6.1.6.3.11.3.1.1
iso.3.6.1.2.1.1.9.1.2.2 = OID: iso.3.6.1.6.3.15.2.1.1
iso.3.6.1.2.1.1.9.1.2.3 = OID: iso.3.6.1.6.3.10.3.1.1
...
etc
Now to enable MIB descriptions instead of OIDs.
Edit the snmp.conf file
sudo nano /etc/snmp/snmp.conf
comment out the line mibs as below, using a #
#mibs
Save, and retry a query.
snmpwalk -v 2c -c public 127.0.0.1 .
It should now show the MIBs descriptions in the results like in this example output.
SNMPv2-MIB::sysDescr.0 = STRING: Linux grafana 4.15.0-72-generic #81-Ubuntu SMP Tue Nov 26 12:20:02 UTC 2019 x86_64
SNMPv2-MIB::sysObjectID.0 = OID: NET-SNMP-MIB::netSnmpAgentOIDs.10
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (3015) 0:00:30.15
SNMPv2-MIB::sysContact.0 = STRING: Me <me@example.org>
SNMPv2-MIB::sysName.0 = STRING: grafana
SNMPv2-MIB::sysLocation.0 = STRING: Sitting on the Dock of the Bay
SNMPv2-MIB::sysServices.0 = INTEGER: 72
SNMPv2-MIB::sysORLastChange.0 = Timeticks: (11) 0:00:00.11
SNMPv2-MIB::sysORID.1 = OID: SNMP-MPD-MIB::snmpMPDCompliance
SNMPv2-MIB::sysORID.2 = OID: SNMP-USER-BASED-SM-MIB::usmMIBCompliance
SNMPv2-MIB::sysORID.3 = OID: SNMP-FRAMEWORK-MIB::snmpFrameworkMIBCompliance
...
etc
Now to configure Telegraf to read SNMP
sudo nano /etc/telegraf/telegraf.conf
Add this script below to the telegraf.conf file.
[[inputs.snmp]]
agents = ["udp://127.0.0.1:161"]
[[inputs.snmp.field]]
oid = "RFC1213-MIB::sysUpTime.0"
name = "uptime"
[[inputs.snmp.field]]
oid = "RFC1213-MIB::sysName.0"
name = "source"
is_tag = true
[[inputs.snmp.table]]
oid = "IF-MIB::ifTable"
name = "interface"
inherit_tags = ["source"]
[[inputs.snmp.table.field]]
oid = "IF-MIB::ifDescr"
name = "ifDescr"
is_tag = true
Save the above configuration addition, restart Telegraf and check status.
sudo service telegraf restart
sudo service telegraf status
⚠️ NOTE : By default SNMPD restricts how much information it returns. So currently we won't get any IF-MIB:: data from a SNMP query.
Go back into snmpd.conf and edit the view section to return more data.
sudo nano /etc/snmp/snmpd.conf
Change lines
...
view systemonly included .1.3.6.1.2.1.1
view systemonly included .1.3.6.1.2.1.25.1
...
to
...
view systemonly included .1.3.6.1.2.1
#view systemonly included .1.3.6.1.2.1.25.1
...
This will now return all data with the OID prefixes .1.3.6.1.2.1 which also includes interface information.
After a few moments, the snmp.table information should be queryable in InfluxDB and in Grafana through the interface measurement.
Sample Queries
Some sample queries to try against the InfluxDB data source in the Grafana explore tab.
from(bucket: "telegraf")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["_measurement"] == "interface")
|> yield(name: "mean")
from(bucket: "telegraf")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["_measurement"] == "snmp")
|> filter(fn: (r) => r["_field"] == "uptime")
|> aggregateWindow(every: v.windowPeriod, fn: mean, createEmpty: false)
|> yield(name: "mean")