SNMP (Simple Network Management Protocol) is how iPM talks to most network hardware, and to any server or appliance that exposes an SNMP agent. Getting it configured correctly is the single biggest factor in whether a device monitors cleanly or gives you nothing but Down/Unknown statuses.
SNMP versions
- v1 and v2c — authenticated with a community string, essentially a shared password sent in plain text. Simple to set up, but weak security, so it's best restricted to trusted internal networks only.
- v3 — supports real authentication and encryption (username, auth protocol/password, privacy protocol/password). Use v3 wherever the device supports it, especially outside a tightly controlled network segment.
Ports and traffic direction
- SNMP polling (iPM asking the device for data) uses UDP 161.
- SNMP traps (the device pushing an alert to iPM unprompted) use UDP 162, if you choose to use trap-based alerting alongside regular polling.
Setting it up
- Enable SNMP on the device itself, and set a community string (v1/v2c) or create an SNMPv3 user (v3).
- If the device has an access list for SNMP, allow the iPM server's IP address.
- When adding the host in iPM (via the Wizard or Auto Discovery), enter the matching SNMP Version, Port, and Community/credentials.
- Confirm the host comes up and, where relevant, that interface- or resource-level services were added automatically.
Common problems
- Wrong community string or SNMPv3 credentials — the single most frequent cause of an SNMP-based service showing Unknown.
- SNMP not enabled on the device, or enabled but restricted to a different subnet/ACL.
- A firewall between iPM and the device blocking UDP 161.
See SNMP Problems in Troubleshooting for a more detailed diagnostic checklist if a device still won't respond after checking the above.