SNMP Monitoring Deep Dive: From OID to Dashboard

SNMP Deep Dive: From OID to Dashboard

SNMP (Simple Network Management Protocol) is the backbone of network monitoring. Understanding it deeply unlocks full visibility into any network device.

SNMP Versions

Version	Security	Use Case
v1	Cleartext	Legacy only
v2c	Cleartext community	Most monitoring
v3	AuthPriv (AES+SHA)	Production

Walking the MIB Tree

BASH

# Install tools
apt install snmp snmp-mibs-downloader

# Walk entire device MIB
snmpwalk -v2c -c public 192.168.1.1

# Get specific OID (CPU on MikroTik)
snmpget -v2c -c public 192.168.1.1 .1.3.6.1.4.1.14988.1.1.3.14.0

# Walk interface table
snmpwalk -v2c -c public 192.168.1.1 IF-MIB::ifTable

Important OIDs

TEXT

# Standard MIB-2
sysDescr:     .1.3.6.1.2.1.1.1.0
sysUpTime:    .1.3.6.1.2.1.1.3.0
ifInOctets:   .1.3.6.1.2.1.2.2.1.10.[ifIndex]
ifOutOctets:  .1.3.6.1.2.1.2.2.1.16.[ifIndex]
ifOperStatus: .1.3.6.1.2.1.2.2.1.8.[ifIndex]

# MikroTik private MIB
CPU load:     .1.3.6.1.4.1.14988.1.1.3.14.0
Free memory:  .1.3.6.1.4.1.14988.1.1.3.6.0
Voltage:      .1.3.6.1.4.1.14988.1.1.3.8.0

SNMP v3 Configuration (MikroTik)

BASH

/snmp set enabled=yes
/snmp community add name=v3comm security=private authentication-protocol=SHA1 authentication-password=AuthPass123 encryption-protocol=AES encryption-password=EncPass123

Custom Zabbix SNMP Template

XML

<item>
    <name>CPU utilization</name>
    <type>SNMP_AGENT</type>
    <snmp_oid>.1.3.6.1.4.1.14988.1.1.3.14.0</snmp_oid>
    <key>mikrotik.cpu</key>
    <delay>60s</delay>
    <units>%</units>
    <triggers>
        <trigger>
            <expression>avg(/Template MikroTik/mikrotik.cpu,5m)>80</expression>
            <name>High CPU: {ITEM.VALUE}%</name>
            <priority>WARNING</priority>
        </trigger>
    </triggers>
</item>

Best Practices

Always use SNMPv3 with AuthPriv in production
Use read-only community strings — never write access
Restrict SNMP access by source IP on the device
Poll at 60s intervals minimum (don't over-poll)