SNMP
Diagnosing SNMP credential, connectivity, and version issues when SNMP data isn't appearing.
Symptoms: Discovery completes, SNMP port (161) detected on hosts, but no SNMP data (sysName, interfaces, LLDP neighbors) appears.
Check credential assignment
Creating a credential alone doesn't activate SNMP. It must be assigned to the network or to specific hosts.
How to verify: Go to Assets > Networks → select the network → check that an SNMP credential is assigned. Or check the host edit modal's Credentials tab to see host-level assignments.
See the SNMP Credentials guide for setup steps, or Troubleshooting credentials for diagnosing file read and loading issues.
Verify the device responds to SNMP
From the daemon host, test SNMP connectivity directly. For SNMPv1/v2c, use the community string:
# Try the default community string
snmpwalk -v2c -c public DEVICE_IP 1.3.6.1.2.1.2.2.1.2
# Try your configured community string
snmpwalk -v2c -c YOUR_COMMUNITY_STRING DEVICE_IP 1.3.6.1.2.1.2.2.1.2For SNMPv3, test with your USM credentials:
snmpwalk -v3 -l authPriv -u SECURITY_NAME \
-a SHA -A AUTH_PASSWORD -x AES -X PRIV_PASSWORD \
DEVICE_IP 1.3.6.1.2.1.2.2.1.2- If
publicworks but your custom string doesn't → credential mismatch - If neither works → SNMP is not enabled on the device, or it doesn't accept the version you're testing
Check SNMP version compatibility
Scanopy supports SNMPv1, SNMPv2c, and SNMPv3. SNMPv3 is AuthPriv only — both authentication and privacy are required, MD5 is not supported (use SHA-1 or SHA-256), and AuthNoPriv/NoAuthNoPriv modes won't connect. If a device enforces SNMPv3-only, configure an SNMPv3 credential rather than a community string.
Check daemon logs
For general credential diagnosis (file path errors, PEM issues, assignment summary), see Troubleshooting credentials.
For SNMP-specific log messages, enable debug logging and look for these messages during a scan of the target host:
| Log message | Meaning |
|---|---|
Creating SNMP community session | Daemon is attempting SNMPv1/v2c |
Creating SNMPv3 session | Daemon is attempting SNMPv3 |
SNMP session created successfully | UDP socket opened |
SNMP GET {name} failed from {ip} | OID query failed (auth or protocol error) |
SNMP GET {name} timeout from {ip} | Device didn't respond within 5s |
SNMP system info retrieved with sys_descr/sys_name | Success |
No working SNMP credential found for {ip} | All credentials tried, none worked |
Check host SNMP data
Open the host edit modal to inspect what SNMP has collected:
- SNMP tab — shows sys_descr, sys_name, sys_location, sys_contact, and credential assignment
- ifEntry tab — shows the interface table from the SNMP walk
If both tabs are empty after a scan with credentials assigned, work through the checks above.