Deep Dive: SNMP Discovery in Open-AudIT

Open-AudIT Community · 2025-12-10 · Tutorials

SNMP (Simple Network Management Protocol) is the backbone of network device management. Open-AudIT supports SNMP v1, v2c, and v3, allowing it to gather rich inventory data from routers, switches, printers, UPS devices, and any other SNMP-capable hardware.

Why SNMP Matters for Asset Inventory

Without SNMP credentials, Open-AudIT can detect that a network device exists (via ICMP/TCP probing) but can't retrieve:

Interface details: IP addresses, VLANs, port descriptions
Hardware model & serial number
Firmware version
Routing tables & ARP cache
Uptime and performance counters

With SNMP configured, all of that becomes available automatically.

Configuring SNMP v2c Credentials

This is the most common configuration for internal networks.

Step 1: Add the Credential

Navigate to Admin → Credentials → Create and fill in:

Field	Value
Name	`Office Switches v2c`
Type	`snmp_v2c`
Community String	`public` (or your actual community string)

Security tip: Avoid using the default public community string in production. Create a read-only community string dedicated to monitoring.

Step 2: Assign to a Discovery

When creating or editing a Discovery, expand the Credentials section and select your newly created SNMP credential.

Step 3: Run the Discovery

After running, check the device record for any switch or router. You should now see a Network Interfaces section populated with interface data.

Configuring SNMP v3

SNMP v3 adds authentication and encryption, making it suitable for secure or compliance-sensitive environments.

# Example SNMPv3 user configuration on a Cisco IOS switch
snmp-server group READONLY v3 priv
snmp-server user open-audit READONLY v3 auth sha MyAuthPass priv aes 128 MyPrivPass
snmp-server view ISO iso included

In Open-AudIT, create the credential with:

Field	Value
Type	`snmp_v3`
Username	`open-audit`
Auth Protocol	`SHA`
Auth Password	`MyAuthPass`
Privacy Protocol	`AES-128`
Privacy Password	`MyPrivPass`

Troubleshooting SNMP Discovery

Device shows as "uncontactable" for SNMP:

Verify the device responds to SNMP from the Open-AudIT server:
```
snmpwalk -v2c -c public <device-ip> sysDescr
```
Check the device's ACL. It may restrict SNMP access to specific source IPs
Ensure UDP port 161 is open between Open-AudIT and the device

Getting No Such Object for some OIDs:

This usually means the device's SNMP view doesn't include that OID tree. Check the SNMP view configuration on the device.

SNMPv3 authentication failures:

Double-check the auth/privacy protocol and passwords. Note that SNMPv3 is case-sensitive: SHA and sha must match what the device expects.

Working with SNMP Data in Open-AudIT

Once SNMP discovery is working, you can leverage the data in several ways:

Network topology maps: Open-AudIT can infer Layer 2 topology from switch MAC tables
VLAN inventory: see which VLANs exist and which ports belong to them
Firmware compliance reports: report on devices running outdated firmware versions

Check out the reporting documentation for examples of SNMP-powered reports.

Community MIBs

Open-AudIT ships with a broad set of vendor MIBs pre-loaded. If you have devices that aren't returning the expected data, check whether a community-contributed MIB is available on our GitHub repo.

Feel free to submit additional MIBs via pull request!

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