[ZBX-26735] Host Discovery with SNMPv3 not working as expected Created: 2025 Jul 21  Updated: 2026 Feb 27

Status: Confirmed
Project: ZABBIX BUGS AND ISSUES
Component/s: Server (S)
Affects Version/s: None
Fix Version/s: None

Type: Incident report Priority: Trivial
Reporter: Melanie te Laake Assignee: Zabbix Support Team
Resolution: Unresolved Votes: 1
Labels: Discovery, SNMP, SNMPv3
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to ZBX-27496 Discovery rules are executed sequent... Needs documenting

 Description   

Automatic discovery using SNMPv3 results in a timeout.
However, querying the same SNMP OID directly from the server cli works without any issues.
Manually adding the host with the same SNMPv3 credentials (authkey, privkey and communtiy) and the same item OID also results in successful item checks.
All queries are executed directly from the Zabbix server, we are not using proxys.

Here is the relevant log snippet:

 

  1716:20250721:143630.556 [17] In discoverer_results_partrange_merge() src:1 dst:0
  1716:20250721:143630.556 [17] End of discoverer_results_partrange_merge() src:1 dst:0
  1716:20250721:143630.556 [17] discovery_net_check_result_flush() results:1 saved:0 ret:0
  1716:20250721:143630.556 In zbx_async_check_snmp() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.11' timeout:4 retries:0 max_repetitions:0
  1716:20250721:143630.556 In zbx_snmp_translate() OID:'1.3.6.1.2.1.1.5.0'
  1716:20250721:143630.556 End of zbx_snmp_translate() oid_translated:'1.3.6.1.2.1.1.5.0'
  1716:20250721:143630.556 snmp_bulkwalk_parse_param() oids_num:1
  1716:20250721:143630.556 In zbx_is_ip4() ip:'10.32.12.11'
  1716:20250721:143630.556 End of zbx_is_ip4():SUCCEED
  1716:20250721:143630.556 In async_dns_event() result:0
  1716:20250721:143630.556 In async_event()
  1716:20250721:143630.556 In snmp_task_process() init event:0 fd:-1 itemid:0
  1716:20250721:143630.556 In zbx_snmp_open_session()
  1716:20250721:143630.556 In zbx_is_ip4() ip:'10.32.12.11'
  1716:20250721:143630.556 End of zbx_is_ip4():SUCCEED
  1716:20250721:143630.593 SNMPv3 [[email protected]:161]
  1716:20250721:143630.593 End of zbx_snmp_open_session()
  1716:20250721:143630.593 In snmp_bulkwalk_add() sending
  1716:20250721:143630.593 In snmp_bulkwalk_add() send completed reqid:8680471
  1716:20250721:143630.593 End of snmp_bulkwalk_add():SUCCEED fd:26
  1716:20250721:143630.593 End of snmp_task_process() init event:0 fd:26 itemid:0 size:0 state:read
  1716:20250721:143630.593 End of async_event():read
  1716:20250721:143630.593 End of async_dns_event()
  1716:20250721:143630.593 End of zbx_async_check_snmp():SUCCEED
  1716:20250721:143630.593 [17] discovery_snmp() ip:10.32.12.11 port:161, key:1.3.6.1.2.1.1.5.0 ret:0

The device have never been added to Zabbix before and is not being restarted.
Since manually adding the hosts works without any issues, I’m not sure what to check on the device side.
The Engine ID is unique, and currently, there are no other SNMPv3 devices in our Zabbix environment.
The same issue has already been reported, but no solution was provided.

https://support.zabbix.com/browse/ZBX-26355

 Comments   
Comment by Aigars Kadikis [ 2025 Jul 22 ]

Thank you for the report. The "Timeout:4" is an attribute of the "zbx_async_check_snmp" function. It is not a result state. The debug log looks healthy. I do not see any "value" about 1.3.6.1.2.1.1.5.0 reported in the debug log. Is it available later?

It's possible host is trying to register. A common issue is that multiple discovery actions match the same devices. To see if it's true:

grep -i "cannot link template" /var/log/zabbix/zabbix_server.log

Or try to disable all discovery actions but enable only one.

Comment by Vladislavs Sokurenko [ 2025 Jul 23 ]

Thank you for your report, it looks like we should add some retries to network discovery using snmp, at least one retry should be done

Comment by Melanie te Laake [ 2025 Jul 23 ]

Thank you for your response. You're right, the timeouts appear further down in the log. I've been able to narrow down the issue a bit.

The problem seems to occur only when scanning network ranges with more than ≈ 200 hosts. In those cases, all requests immediately result in timeouts. The discovery work fine when I set the "Maximum concurrent checks per type" in the discovery rule to Custom: 50.

At first, I suspected our firewall might be blocking or throttling too many parallel requests, but I haven’t seen anything unusual in the logs. I also tested the same setup using SNMPv2, and in that case, the checks work without issues even with the setting at Unlimited.
I can live with limiting the number of concurrent checks on our side, but it's quite odd that this issue only occurs with SNMPv3. That inconsistency is still a bit puzzling.

The Log ( 10.32.12.11-13 are active devices that should be found ): 

1490084:20250722:172050.794 End of process_results() ret:0
1490084:20250722:172050.794 zbx_setproctitle() title:'discovery manager #1 [processing 0 rules, 0 unsaved checks]'
1490084:20250722:172050.794 In process_discovery()
1490084:20250722:172050.794 In substitute_simple_macros_impl() data:'5m'
1490084:20250722:172050.794 End substitute_simple_macros_impl() data:'5m'
1490084:20250722:172050.794 In substitute_simple_macros_impl() data:'4s'
1490084:20250722:172050.795 End substitute_simple_macros_impl() data:'4s'
1490084:20250722:172050.795 In process_rule() rule:'Aruba Access' range:'10.32.12.10-195'
1490084:20250722:172050.795 process_rule() range:'10.32.12.10-195'
1490084:20250722:172050.795 In substitute_simple_macros_impl() data:EMPTY
1490084:20250722:172050.795 In substitute_key_macros_impl() data:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172050.795 End of substitute_key_macros_impl():SUCCEED data:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172050.795 In substitute_simple_macros_impl() data:'*****'
1490084:20250722:172050.795 End substitute_simple_macros_impl() data:'******'
1490084:20250722:172050.795 In substitute_simple_macros_impl() data:'{$SNMP_AUTHPASS}'
1490084:20250722:172050.795 In um_cache_resolve() macro:'{$SNMP_AUTHPASS}'
1490084:20250722:172050.795 End of um_cache_resolve(): *UNKNOWN*
1490084:20250722:172050.795 End substitute_simple_macros_impl() data:'*********'
1490084:20250722:172050.795 In substitute_simple_macros_impl() data:'{$SNMP_PRIVPASS}'
1490084:20250722:172050.795 In um_cache_resolve() macro:'{$SNMP_PRIVPASS}'
1490084:20250722:172050.795 End of um_cache_resolve(): *UNKNOWN*
1490084:20250722:172050.795 End substitute_simple_macros_impl() data:'*********'
1490084:20250722:172050.795 In substitute_simple_macros_impl() data:EMPTY
1490084:20250722:172050.795 End of process_rule() drule:30 tasks:1 check_counts(ip):186 checks_count:1
1490084:20250722:172050.795 In discoverer_clean_services()
1490084:20250722:172050.795 query [txnlev:0] [select iprange from drules where druleid=30]
1490084:20250722:172050.796 query [txnlev:0] [select dh.dhostid,ds.dserviceid,ds.ip from dhosts dh left join dservices ds on dh.dhostid=ds.dhostid where dh.druleid=30]
1490084:20250722:172050.796 In zbx_ip_in_list() list:'10.32.12.10-195' ip:'10.32.12.13'
1490084:20250722:172050.796 End of zbx_ip_in_list():SUCCEED
1490084:20250722:172050.796 In zbx_ip_in_list() list:'10.32.12.10-195' ip:'10.32.12.12'
1490084:20250722:172050.796 End of zbx_ip_in_list():SUCCEED
1490084:20250722:172050.796 In zbx_ip_in_list() list:'10.32.12.10-195' ip:'10.32.12.11'
1490084:20250722:172050.796 End of zbx_ip_in_list():SUCCEED
1490084:20250722:172050.797 In zbx_ip_in_list() list:'10.32.12.10-195' ip:'10.32.12.14'
1490084:20250722:172050.797 End of zbx_ip_in_list():SUCCEED
1490084:20250722:172050.797 End of discoverer_clean_services()
1490084:20250722:172050.797 End of process_discovery() rule_count:1 nextcheck:1753228808
1490084:20250722:172050.797 [13] In discovery_net_check_range() druleid:30 range id:63 state.count:186 checks per ip:1 dchecks:1 type:13 concurrency_max:0 checks_per_worker_max:1000
1490084:20250722:172050.797 [13] In discovery_async_poller_init()
1490084:20250722:172050.797 In zbx_ipc_service_recv() timeout:5.000
1490084:20250722:172050.797 [13] End of discovery_async_poller_init()
1490084:20250722:172050.797 In zbx_async_check_snmp() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.10' timeout:4 retries:0 max_repetitions:0
1490084:20250722:172050.797 In zbx_snmp_translate() OID:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172050.797 End of zbx_snmp_translate() oid_translated:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172050.798 snmp_bulkwalk_parse_param() oids_num:1
1490084:20250722:172050.798 In zbx_is_ip4() ip:'10.32.12.10'
1490084:20250722:172050.798 End of zbx_is_ip4():SUCCEED
1490084:20250722:172050.798 In async_dns_event() result:0
1490084:20250722:172050.798 In async_event()
1490084:20250722:172050.798 In snmp_task_process() init event:0 fd:-1 itemid:0
1490084:20250722:172050.798 In zbx_snmp_open_session()
1490084:20250722:172050.798 In zbx_is_ip4() ip:'10.32.12.10'
1490084:20250722:172050.798 End of zbx_is_ip4():SUCCEED
1490084:20250722:172050.834 SNMPv3 [[email protected]:161]
1490084:20250722:172050.834 End of zbx_snmp_open_session()
1490084:20250722:172050.834 In snmp_bulkwalk_add() sending
1490084:20250722:172050.834 In snmp_bulkwalk_add() send completed reqid:1253349464
1490084:20250722:172050.834 End of snmp_bulkwalk_add():SUCCEED fd:25
1490084:20250722:172050.834 End of snmp_task_process() init event:0 fd:25 itemid:0 size:0 state:read
1490084:20250722:172050.834 End of async_event():read
1490084:20250722:172050.835 End of async_dns_event()
1490084:20250722:172050.835 End of zbx_async_check_snmp():SUCCEED
1490084:20250722:172050.835 [13] discovery_snmp() ip:10.32.12.10 port:161, key:1.3.6.1.2.1.1.5.0 ret:0
1490084:20250722:172050.835 [13] In discoverer_results_partrange_merge() src:1 dst:0
1490084:20250722:172050.835 [13] End of discoverer_results_partrange_merge() src:1 dst:0
1490084:20250722:172050.835 [13] discovery_net_check_result_flush() results:1 saved:0 ret:0
1490084:20250722:172050.835 In zbx_async_check_snmp() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.11' timeout:4 retries:0 max_repetitions:0
1490084:20250722:172050.835 In zbx_snmp_translate() OID:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172050.835 End of zbx_snmp_translate() oid_translated:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172050.835 snmp_bulkwalk_parse_param() oids_num:1
1490084:20250722:172050.835 In zbx_is_ip4() ip:'10.32.12.11'
1490084:20250722:172050.835 End of zbx_is_ip4():SUCCEED
1490084:20250722:172050.835 In async_dns_event() result:0
1490084:20250722:172050.835 In async_event()
1490084:20250722:172050.835 In snmp_task_process() init event:0 fd:-1 itemid:0
1490084:20250722:172050.835 In zbx_snmp_open_session()
1490084:20250722:172050.835 In zbx_is_ip4() ip:'10.32.12.11'
1490084:20250722:172050.835 End of zbx_is_ip4():SUCCEED
1490084:20250722:172050.872 SNMPv3 [[email protected]:161]
1490084:20250722:172050.872 End of zbx_snmp_open_session()
1490084:20250722:172050.872 In snmp_bulkwalk_add() sending
1490084:20250722:172050.872 In snmp_bulkwalk_add() send completed reqid:1253349465
1490084:20250722:172050.872 End of snmp_bulkwalk_add():SUCCEED fd:26
1490084:20250722:172050.872 End of snmp_task_process() init event:0 fd:26 itemid:0 size:0 state:read
1490084:20250722:172050.872 End of async_event():read
1490084:20250722:172050.872 End of async_dns_event()
1490084:20250722:172050.872 End of zbx_async_check_snmp():SUCCEED
1490084:20250722:172050.872 [13] discovery_snmp() ip:10.32.12.11 port:161, key:1.3.6.1.2.1.1.5.0 ret:0
....
....

1490084:20250722:172055.467 [13] discovery_snmp() ip:10.32.12.194 port:161, key:1.3.6.1.2.1.1.5.0 ret:0
1490084:20250722:172055.467 In zbx_async_check_snmp() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.195' timeout:4 retries:0 max_repetitions:0
1490084:20250722:172055.467 In zbx_snmp_translate() OID:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172055.467 End of zbx_snmp_translate() oid_translated:'1.3.6.1.2.1.1.5.0'
1490084:20250722:172055.467 snmp_bulkwalk_parse_param() oids_num:1
1490084:20250722:172055.467 In zbx_is_ip4() ip:'10.32.12.195'
1490084:20250722:172055.467 End of zbx_is_ip4():SUCCEED
1490084:20250722:172055.467 In async_dns_event() result:0
1490084:20250722:172055.467 In async_event()
1490084:20250722:172055.467 In snmp_task_process() init event:0 fd:-1 itemid:0
1490084:20250722:172055.467 In zbx_snmp_open_session()
1490084:20250722:172055.467 In zbx_is_ip4() ip:'10.32.12.195'
1490084:20250722:172055.467 End of zbx_is_ip4():SUCCEED
1490084:20250722:172055.483 SNMPv3 [[email protected]:161]
1490084:20250722:172055.483 End of zbx_snmp_open_session()
1490084:20250722:172055.483 In snmp_bulkwalk_add() sending
1490084:20250722:172055.484 In snmp_bulkwalk_add() send completed reqid:1253349649
1490084:20250722:172055.484 End of snmp_bulkwalk_add():SUCCEED fd:210
1490084:20250722:172055.484 End of snmp_task_process() init event:0 fd:210 itemid:0 size:0 state:read
1490084:20250722:172055.484 End of async_event():read
1490084:20250722:172055.484 End of async_dns_event()
1490084:20250722:172055.484 End of zbx_async_check_snmp():SUCCEED
1490084:20250722:172055.484 [13] discovery_snmp() ip:10.32.12.195 port:161, key:1.3.6.1.2.1.1.5.0 ret:0
1490084:20250722:172055.484 In async_event()
1490084:20250722:172055.484 In snmp_task_process() read event:2 fd:26 itemid:0
1490084:20250722:172055.484 In asynch_response()
1490084:20250722:172055.484 operation:1 response id:1253349465 command:168 probe:1
1490084:20250722:172055.484 End of asynch_response():SUCCEED
1490084:20250722:172055.484 In asynch_response()
1490084:20250722:172055.484 operation:7 response id:1253349465 command:168 probe:1
1490084:20250722:172055.484 End of asynch_response():SUCCEED
1490084:20250722:172055.484 In snmp_bulkwalk_add() OID: '.1.3.6.1.2.1.1.5.0'
1490084:20250722:172055.484 In snmp_bulkwalk_add() sending
1490084:20250722:172055.484 In snmp_bulkwalk_add() send completed reqid:1253349650
1490084:20250722:172055.484 End of snmp_bulkwalk_add():SUCCEED fd:26
1490084:20250722:172055.484 End of snmp_task_process() read event:2 fd:26 itemid:0 size:0 state:read
1490084:20250722:172055.484 End of async_event():read
1490084:20250722:172055.484 In async_event()
1490084:20250722:172055.484 In snmp_task_process() read event:2 fd:27 itemid:0
1490084:20250722:172055.484 In asynch_response()
1490084:20250722:172055.484 operation:1 response id:1253349466 command:168 probe:1
1490084:20250722:172055.484 End of asynch_response():SUCCEED
1490084:20250722:172055.484 In asynch_response()
1490084:20250722:172055.484 operation:7 response id:1253349466 command:168 probe:1
1490084:20250722:172055.484 End of asynch_response():SUCCEED
1490084:20250722:172055.484 In snmp_bulkwalk_add() OID: '.1.3.6.1.2.1.1.5.0'
1490084:20250722:172055.484 In snmp_bulkwalk_add() sending
1490084:20250722:172055.484 In snmp_bulkwalk_add() send completed reqid:1253349651
1490084:20250722:172055.484 End of snmp_bulkwalk_add():SUCCEED fd:27
1490084:20250722:172055.484 End of snmp_task_process() read event:2 fd:27 itemid:0 size:0 state:read
1490084:20250722:172055.484 End of async_event():read
1490084:20250722:172055.484 In async_event()
1490084:20250722:172055.484 In snmp_task_process() read event:2 fd:28 itemid:0
1490084:20250722:172055.484 In asynch_response()
1490084:20250722:172055.484 operation:1 response id:1253349467 command:168 probe:1
1490084:20250722:172055.484 End of asynch_response():SUCCEED
1490084:20250722:172055.484 In asynch_response()
1490084:20250722:172055.485 operation:7 response id:1253349467 command:168 probe:1
1490084:20250722:172055.485 End of asynch_response():SUCCEED
1490084:20250722:172055.485 In snmp_bulkwalk_add() OID: '.1.3.6.1.2.1.1.5.0'
1490084:20250722:172055.485 In snmp_bulkwalk_add() sending
1490084:20250722:172055.485 In snmp_bulkwalk_add() send completed reqid:1253349652
1490084:20250722:172055.485 End of snmp_bulkwalk_add():SUCCEED fd:28
1490084:20250722:172055.485 End of snmp_task_process() read event:2 fd:28 itemid:0 size:0 state:read
1490084:20250722:172055.485 End of async_event():read
1490084:20250722:172055.485 In async_event()
1490084:20250722:172055.485 In snmp_task_process() read event:2 fd:29 itemid:0
1490084:20250722:172055.485 In asynch_response()
1490084:20250722:172055.485 operation:1 response id:1253349468 command:168 probe:1
1490084:20250722:172055.485 End of asynch_response():SUCCEED
1490084:20250722:172055.485 In asynch_response()
1490084:20250722:172055.485 operation:7 response id:1253349468 command:168 probe:1
1490084:20250722:172055.485 End of asynch_response():SUCCEED
1490084:20250722:172055.485 In snmp_bulkwalk_add() OID: '.1.3.6.1.2.1.1.5.0'
1490084:20250722:172055.485 In snmp_bulkwalk_add() sending
1490084:20250722:172055.485 In snmp_bulkwalk_add() send completed reqid:1253349653
1490084:20250722:172055.485 End of snmp_bulkwalk_add():SUCCEED fd:29
1490084:20250722:172055.485 End of snmp_task_process() read event:2 fd:29 itemid:0 size:0 state:read
1490084:20250722:172055.485 End of async_event():read
1490084:20250722:172055.485 In async_event()
1490084:20250722:172055.485 In snmp_task_process() timeout event:1 fd:-1 itemid:0
1490084:20250722:172055.485 End of snmp_task_process():TIMEOUT_ERROR timeout event:1 fd:-1 itemid:0 size:0 error:cannot retrieve OID: '.1.3.6.1.2.1.1.5.0' from [[10.32.12.10]:161]: timed out
1490084:20250722:172055.485 [13] In process_snmp_result() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.10' ret:TIMEOUT_ERROR
1490084:20250722:172055.485 In zbx_snmp_close_session()
1490084:20250722:172055.485 In asynch_response()
1490084:20250722:172055.485 operation:2 response id:1253349464 command:160 probe:1
1490084:20250722:172055.485 End of asynch_response():SUCCEED
1490084:20250722:172055.485 End of zbx_snmp_close_session()
1490084:20250722:172055.485 [13] End of process_snmp_result()
1490084:20250722:172055.485 End of async_event():stop
1490084:20250722:172055.485 In async_event()
1490084:20250722:172055.485 In snmp_task_process() timeout event:1 fd:-1 itemid:0
1490084:20250722:172055.485 End of snmp_task_process():TIMEOUT_ERROR timeout event:1 fd:-1 itemid:0 size:0 error:Probe successful, cannot retrieve OID: '.1.3.6.1.2.1.1.5.0' from [[10.32.12.11]:161]: timed out
1490084:20250722:172055.485 [13] In process_snmp_result() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.11' ret:TIMEOUT_ERROR
1490084:20250722:172055.485 In zbx_snmp_close_session()
1490084:20250722:172055.485 In asynch_response()
1490084:20250722:172055.485 operation:2 response id:1253349650 command:160 probe:0
1490084:20250722:172055.485 operation:2 response id:1253349650 timed out, snmp_error:Timeout
1490084:20250722:172055.485 In snmp_bulkwalk_handle_response()
1490084:20250722:172055.485 snmp_bulkwalk_handle_response() response error: Timeout while connecting to "10.32.12.11:161".
1490084:20250722:172055.485 End of snmp_bulkwalk_handle_response():NETWORK_ERROR running:0 count:0 snmp_error:Unknown error: 2
1490084:20250722:172055.485 End of asynch_response():NETWORK_ERROR
1490084:20250722:172055.485 End of zbx_snmp_close_session()
1490084:20250722:172055.485 [13] End of process_snmp_result()
1490084:20250722:172055.486 End of async_event():stop
1490084:20250722:172055.486 In async_event()
1490084:20250722:172055.486 In snmp_task_process() timeout event:1 fd:-1 itemid:0
1490084:20250722:172055.486 End of snmp_task_process():TIMEOUT_ERROR timeout event:1 fd:-1 itemid:0 size:0 error:Probe successful, cannot retrieve OID: '.1.3.6.1.2.1.1.5.0' from [[10.32.12.12]:161]: timed out
1490084:20250722:172055.486 [13] In process_snmp_result() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.12' ret:TIMEOUT_ERROR
1490084:20250722:172055.486 In zbx_snmp_close_session()
1490084:20250722:172055.486 In asynch_response()
1490084:20250722:172055.486 operation:2 response id:1253349651 command:160 probe:0
1490084:20250722:172055.486 operation:2 response id:1253349651 timed out, snmp_error:Timeout
1490084:20250722:172055.486 In snmp_bulkwalk_handle_response()
1490084:20250722:172055.486 snmp_bulkwalk_handle_response() response error: Timeout while connecting to "10.32.12.12:161".
1490084:20250722:172055.486 End of snmp_bulkwalk_handle_response():NETWORK_ERROR running:0 count:0 snmp_error:Unknown error: 2
1490084:20250722:172055.486 End of asynch_response():NETWORK_ERROR
1490084:20250722:172055.486 End of zbx_snmp_close_session()
1490084:20250722:172055.486 [13] End of process_snmp_result()
1490084:20250722:172055.486 End of async_event():stop
1490084:20250722:172055.486 In async_event()
1490084:20250722:172055.486 In snmp_task_process() timeout event:1 fd:-1 itemid:0
1490084:20250722:172055.486 End of snmp_task_process():TIMEOUT_ERROR timeout event:1 fd:-1 itemid:0 size:0 error:Probe successful, cannot retrieve OID: '.1.3.6.1.2.1.1.5.0' from [[10.32.12.13]:161]: timed out
1490084:20250722:172055.486 [13] In process_snmp_result() key:'1.3.6.1.2.1.1.5.0' host:'' addr:'10.32.12.13' ret:TIMEOUT_ERROR
1490084:20250722:172055.486 In zbx_snmp_close_session()
1490084:20250722:172055.486 In asynch_response()
1490084:20250722:172055.486 operation:2 response id:1253349652 command:160 probe:0
1490084:20250722:172055.486 operation:2 response id:1253349652 timed out, snmp_error:Timeout
1490084:20250722:172055.486 In snmp_bulkwalk_handle_response()
1490084:20250722:172055.486 snmp_bulkwalk_handle_response() response error: Timeout while connecting to "10.32.12.13:161".
1490084:20250722:172055.486 End of snmp_bulkwalk_handle_response():NETWORK_ERROR running:0 count:0 snmp_error:Unknown error: 2
1490084:20250722:172055.486 End of asynch_response():NETWORK_ERROR
1490084:20250722:172055.486 End of zbx_snmp_close_session()
1490084:20250722:172055.486 [13] End of process_snmp_result()
1490084:20250722:172055.486 End of async_event():stop
1490084:20250722:172055.486 In async_event()
1490084:20250722:172055.486 In snmp_task_process() timeout event:1 fd:-1 itemid:0
1490084:20250722:172055.486 End of snmp_task_process():TIMEOUT_ERROR timeout event:1 fd:-1 itemid:0 size:0 error:Probe successful, cannot retrieve OID: '.1.3.6.1.2.1.1.5.0' from [[10.32.12.14]:161]: timed out
...
...
Comment by Vladislavs Sokurenko [ 2025 Jul 23 ]

SNMPv3 does a little bit more due to security so it's one extra packet for probe.

Comment by Melanie te Laake [ 2025 Jul 23 ]

It is an additional package, but it uses the same stateful session. The same UDP ports are used as during the initial connection.
I don't know how the discovery is implemented internally, but if "unlimited" triggers all queries simultaneously, I’ve now tested it with SNMPv2 and a /21 subnet as well. The discovery works without any issues in this setup, too. This should cover more than double the number of packets.

Comment by Joren [ 2026 Feb 27 ]

Is there any update regarding this issue? I have also came to the same conclusion that using the Unlimited option for "Maximum concurrent checks per type" make discovery not work at all.

It currently discovers when I set it to a any custom value it seems, in my case I chose 5. But unlimited simply breaks it and it does not discover anything.

Using SNMPv3 as well, simply using the zabbix server not a proxy

Comment by Vladislavs Sokurenko [ 2026 Feb 27 ]

Might be related to ZBX-27496

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