v3 authPriv traps not received on snmptd on linux security service 3 error parsing ScopedPDU

Products

• DX Unified Infrastructure Management (Nimsoft / UIM)

Issue/Introduction

Testing snmptd probe version 3.40, we are able to receive the V3 authPriv traps if the probe is deployed on Windows. 

When the probe is running on Linux the v3 authPriv traps are correctly received at the probe's trap monitor. 

On linux, also v2, and v3 AuhtNoprovi traps are received, so the issue is limited to V3 authPriv traps on Linux only.

 

Oct 18 09:39:01:210 [139741187688192] snmptd: usm: match on user goober 
Oct 18 09:39:01:210 [139741187688192] snmptd: usm: Verification succeeded. 
Oct 18 09:39:01:210 [139741187688192] snmptd: usm: USM processing completed. 
Oct 18 09:39:11:037 [139741187688192] snmptd: security service 3 error parsing ScopedPDU 
Oct 18 09:39:11:037 [139741187688192] snmptd: USM processing begun... 
Oct 18 09:39:11:037 [139741187688192] snmptd: match on user goober 
Oct 18 09:39:11:037 [139741187688192] snmptd: Verification succeeded. 
Oct 18 09:39:11:037 [139741187688192] snmptd: USM processing completed.  

Environment

• DX UIM 23.4.*
• snmptd 3.40

Cause

The current version of snmptd 3.40 is unable to handle SNMPv3 traps with authPriv in most Linux flavors. This is due to an existing issue in the Net-SNMP library, which has been present since version 5.8 and persists in the latest 5.9.4 release.

References:

• SourceForge Bug #2947
• GitHub Issue #676

 

Resolution

[DE618747] Since Net-SNMP lib has introduced major changes around this area this Engineering needs to dig deep in net-snmp code to resolve this issue. Broadcom has engaged Net-SNMP to discuss a probable fix for this issue. No ETA as of February 2025. 

Workaround:
As a temporary solution, customers can use snmptd 3.30, which does not exhibit this issue for similar traps.

The probe version 3.30 is attached to this KB: