- While working with SNMPv3 with a specific SNMP agent, we encountered problems with SNMPv3 “Time synchronization”, some research determined that this error could be ignored, so modifying the Net::SNMP Perl library could workaround this problem.
- If you encounter the 'Time synchronization failed during discovery' error using the perl Net::SNMP library there may be a fairly easy
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- work around.
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- It may be as easy as editing the Net::SNMP module to not invoke this error.
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- The following advice should be executed as root.
- The following was done with the Net::SNMP Version 6.0.1 package. If this library is upgraded, this patch may need to be reapplied.
Find Net::SNMP
In order to find where Net::SNMP is on the subject system issue the following command.
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If you are unfortunate as in the above example, two SNMP.pm files may be returned. In order to determine which one perl is invoking use the perl -V command.
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The @INC array is a list of directories that perl looks in to find modules. This is a top down, first match first find operation. Based on this the version in /usr/local/share/perl5/Net will be utilized because it will be found first.
Edit Net::SNMP
Always make a backup of a module prior to editing it. In order to prevent Net::SNMP from failing due to this error we edited it in the following fashion.
We were able to get the agent to work by doing the following:
- Commenting out part of the if statement on line 2545. (The if statement will need to be re-written)
- Commenting out lines 2562 through 2565.
| Code Block | ||
|---|---|---|
| ||
2544 if (($this->{_security}->discovered) &&
2545 ($this->{_error} =~ /usmStatsNotInTimeWindows/))
2546 {
2547 $this->_error_clear;
2548
2549 DEBUG_INFO('discovery and synchronization complete');
2550
2551 # Discovery is complete, send any pending messages
2552 while (my $q = shift(@{$this->{_discovery_queue}})) {
2553 $DISPATCHER->send_pdu(@{$q});
2554 }
2555
2556 return TRUE;
2557 }
2558
2559 | ||
| Code Block | ||
$ diff -bu SNMP.pm.original SNMP.pm.patched --- SNMP.pm.original 2018-01-26 08:36:28.833348881 +0900 +++ SNMP.pm.patched 2018-01-26 14:25:42.798070662 +0900 @@ -2617,8 +2617,9 @@ # counter in the varBindList..." If another error is returned, we # assume that the synchronization has failed. - if (($this->{_security}->discovered()) && - ($this->{_error} =~ /usmStatsNotInTimeWindows/)) + if ($this->{_security}->discovered()) + #if (($this->{_security}->discovered()) && + # ($this->{_error} =~ /usmStatsNotInTimeWindows/)) { $this->_error_clear(); DEBUG_INFO('discovery and synchronization complete'); @@ -2628,10 +2629,10 @@ # If we received the usmStatsNotInTimeWindows report or no error, but 2560 # we are still not synchronized, provide a generic error message. 2561 -2562 if ((!$this->{_error}) || ($this->{_error} =~ /usmStatsNotInTimeWindows/)) { -2563 $this->_error_clear(); -2564 $this->_error('Time synchronization failed during discovery'); -2565 } + #if ((!$this->{_error}) || ($this->{_error} =~ /usmStatsNotInTimeWindows/)) { + # $this->_error_clear(); + # $this->_error('Time synchronization failed during discovery'); + #} DEBUG_INFO('synchronization failed'); |
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