SNMP Discovery for Industrial Asset Inventory
Overview
SNMP supplies standardized identity, interface, and physical-component data across managed switches, controllers, servers, and other networked equipment. OTserver makes SNMP optional because it requires an operator-supplied access profile.
How OTserver discovers assets with SNMP
OTserver connects to UDP port 161 with an SNMPv2c or SNMPv3 profile. It starts with a multi-value GET for system description, object ID, name, and location, then walks selected standard MIB tables.
SNMPv3 profiles support MD5 and SHA-family authentication plus DES or AES privacy options. Secrets come from named environment variables or masked, in-memory GUI overrides; they are not written to scan exports or logs.
Evidence extracted
| OTserver evidence | MIB source |
|---|---|
| Description and operating-system hint | sysDescr.0 |
| Name | sysName.0 |
| Location | sysLocation.0 |
| Interfaces | IF-MIB description, MTU, speed, MAC, admin state, and operational state |
| High-speed interfaces | IF-MIB ifHighSpeed |
| Firmware, serial, vendor, and model | ENTITY-MIB physical inventory |
| Additional network evidence | IP-MIB address table and BRIDGE-MIB |
Walks are limited to 4,000 results, and optional tables that a device does not expose are skipped without discarding the valid system evidence.
Security and read-only safety
OTserver uses SNMP GET and WALK only; it never sends SNMP SET. Prefer SNMPv3 authentication and privacy where devices support it, give the scanner a read-only account, and restrict access with device ACLs. SNMP inventory and LLDP topology discovery have independent scanner toggles even though both use the SNMP profile.
Frequently asked questions
Can OTserver scan SNMP without storing a community or password?
Yes. Profiles name environment variables that hold credentials. GUI overrides remain in process memory for the current scan and are not persisted or exported.
Does OTserver use vendor-specific MIBs?
The current implementation uses standard system, IF-MIB, IP-MIB, BRIDGE-MIB, ENTITY-MIB, and LLDP MIB trees. It preserves returned OIDs as raw evidence but does not add vendor-specific write or control operations.
Compare all supported discovery protocols or configure SNMP profiles.