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The following upstream bug appears to affect net-snmp-5.5-54.el6_7.1. https://sourceforge.net/p/net-snmp/bugs/2482/ "An SNMPv3 request with a small max message size can lead to SNMPv1/2c bulk requests timing out. This is because when sending a response the length of the data is checked against a max message property of the session and if it is too big then a "snmp response: Too large" log message is generated. Now the max message size session property is a SNMPv3 thing. For SNMPv1/2c this is normally set to zero which disables this check. So as long as we talk to the agent using SNMPv1/2c everything is fine. Now things get broken when a SNMPv3 request arrives (you do not need valid credentials for this!). This request provides a max message size property which is recorded in the session. So all the following SNMPv1/2c responses are checked against the last SNMPv3 max message size property. If the response is large enough (e.g. snmpbulkget -Cr100 ...) it will not be sent out. To recover from this either restart the agent or send a SNMPv3 request with a large max message size property. The fix would be to enable the test against the session max message size in _sess_async_send() which is in snmplib/snmp_api.c for SNMPv3 only. I attached a script that triggers this. It requires Net::SNMP perl module installed and is called with the target host as parameter. The read community is assumed to be "public"."
Upstream fix is in the V5-5-patches branch: commit a93991eaf53b199b19c582b630da25158300a9d1 Author: Robert Story <rstory@localhost> Date: Fri Aug 1 10:07:45 2014 -0400 fix #2482 snmp response: Too long
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHBA-2017-0597.html