We're working on a script using Net-SNMP that will talk to devices using both SNMPv1 and v3. (The plan is to automate the device configurations en masse to use v3.) We're coming across a very strange problem where the script gets hung after we issue bulkwalk commands followed by a MainLoop call:

    foreach my $host (@{$hashRef->{hostArray}}){
        
        printf "Starting SNMP bulkwalk for %s\n", $host if($DEBUG);
        
        $hashRef->{config}->{DestHost} = $host;
        
        my $session = SNMP::Session->new( %{$hashRef->{config}} );
        
        die("No session\n") if(!$session);
        $session->bulkwalk($hashRef->{snmpSingle}, $hashRef->{snmpBulk
+}, $hashRef->{varList}, [\&snmpCallback, $session, $host, \$arraySize
+, \%snmpData]);
    }

    print "Just before Main Loop\n";
    SNMP::MainLoop();
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We're getting this running v3 which is behaving as predicted:

trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,SESSION_INIT)
trace: snmp_call_callbacks(): callback.c, 322:
callback: START calling callbacks for maj=0 min=5
trace: snmp_call_callbacks(): callback.c, 336:
callback: calling a callback for maj=0 min=5
trace: snmp_call_callbacks(): callback.c, 348:
callback: END calling callbacks for maj=0 min=5 (1 called)
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SESSION_INIT)
trace: snmp_sess_add_ex(): snmp_api.c, 1683:
snmp_sess_add: adding v3 session -- maybe engineID probe now
trace: usm_get_user(): snmpusm.c, 2994:
usm: getting user 
trace: snmpv3_engineID_probe(): snmp_api.c, 1409:
snmp_api: probing for engineID...
trace: snmpv3_build(): snmp_api.c, 2330:
snmp_build: Building SNMPv3 message (secName:"dcosnmpadmin", secLevel:
+noAuthNoPriv)...
<snip>
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But when I run it using v1 it hangs:

trace: _callback_lock(): callback.c, 130:
9:callback:lock: locked (LIB,SESSION_INIT)
trace: snmp_call_callbacks(): callback.c, 322:
callback: START calling callbacks for maj=0 min=5
trace: snmp_call_callbacks(): callback.c, 336:
callback: calling a callback for maj=0 min=5
trace: snmp_call_callbacks(): callback.c, 348:
callback: END calling callbacks for maj=0 min=5 (1 called)
trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SESSION_INIT)
trace: _sess_async_send(): snmp_api.c, 5067:
sess_async_send: encoding failure
trace: snmp_sess_select_info2(): snmp_api.c, 6188:
sess_select: for all sessions: 4 
sess_select: blocking:no session requests or alarms.
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And it ends there. El Goog did not return anything helpful with the msgs from STDERR.

Here's the output from STDOUT:

trace: _callback_unlock(): callback.c, 164:
9:callback:lock: unlocked (LIB,SESSION_INIT)
trace: _sess_async_send(): snmp_api.c, 5067:
sess_async_send: encoding failure
Just before Main Loop
trace: snmp_sess_select_info2(): snmp_api.c, 6188:
sess_select: for all sessions: 4
sess_select: blocking:no session requests or alarms.
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If anyone has a clue as what's going on pls share it with me - I'd be very appreciative!!!

- Joe