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TrapReceiver(3) 	       User Contributed Perl Documentation		  TrapReceiver(3)

NAME
       NetSNMP::TrapReceiver - Embedded perl trap handling for Net-SNMP's snmptrapd

SYNOPSIS
       Put the following lines in your snmptrapd.conf file:

	 perl NetSNMP::TrapReceiver::register("trapOID", \&myfunc);

ABSTRACT
       The NetSNMP::TrapReceiver module is used to register perl subroutines into the Net-SNMP
       snmptrapd process.  Net-SNMP MUST have been configured using --enable-embedded-perl.
       Registration of functions is then done through the snmptrapd.conf configuration file.
       This module can NOT be used in a normal perl script to receive traps.  It is intended
       solely for embedded use within the snmptrapd demon.

DESCRIPTION
       Within the snmptrapd.conf file, the keyword "perl" may be used to call any perl expression
       and using this ability, you can use the NetSNMP::TrapReceiver module to register functions
       which will be called every time a given notification (a trap or an inform) is received.
       Registered functions are called with 2 arguments.  The first is a reference to a hash
       containing information about how the trap was received (what version of the SNMP protocol
       was used, where it came from, what SNMP user name or community name it was sent under,
       etc).  The second argument is a reference to an array containing the variable bindings
       (OID and value information) that define the noification itself.	Each variable is itself a
       reference to an array containing three values: a NetSNMP::OID object, the value that came
       associated with it, and the value's numeric type (see NetSNMP::ASN for further details on
       SNMP typing information).

       Registered functions should return one of the following values:

       NETSNMPTRAPD_HANDLER_OK
	 Handling the trap succeeded, but lets the snmptrapd demon check for further appropriate
	 handlers.

       NETSNMPTRAPD_HANDLER_FAIL
	 Handling the trap failed, but lets the snmptrapd demon check for further appropriate
	 handlers.

       NETSNMPTRAPD_HANDLER_BREAK
	 Stops evaluating the list of handlers for this specific trap, but lets the snmptrapd
	 demon apply global handlers.

       NETSNMPTRAPD_HANDLER_FINISH
	 Stops searching for further appropriate handlers.

       If a handler function does not return anything appropriate or even nothing at all, a
       return value of NETSNMPTRAPD_HANDLER_OK is assumed.

       Subroutines are registered using the NetSNMP::TrapReceiver::register function, which takes
       two arguments.  The first is a string describing the notification you want to register for
       (such as "linkUp" or "MyMIB::MyTrap" or ".1.3.6.1.4.1.2021....").  Two special keywords
       can be used in place of an OID: "default" and "all".  The "default" keyword indicates you
       want your handler to be called in the case where no other handlers are called.  The "all"
       keyword indicates that the handler should ALWAYS be called for every notification.

EXAMPLE
       As an example, put the following code into a file (say
       "/usr/local/share/snmp/mytrapd.pl"):

	 #!/usr/bin/perl

	 sub my_receiver {
	     print "********** PERL RECEIVED A NOTIFICATION:\n";

	     # print the PDU info (a hash reference)
	     print "PDU INFO:\n";
	     foreach my $k(keys(%{$_[0]})) {
	       if ($k eq "securityEngineID" || $k eq "contextEngineID") {
		 printf "  %-30s 0x%s\n", $k, unpack('h*', $_[0]{$k});
	       }
	       else {
		 printf "  %-30s %s\n", $k, $_[0]{$k};
	       }
	     }

	     # print the variable bindings:
	     print "VARBINDS:\n";
	     foreach my $x (@{$_[1]}) {
		 printf "  %-30s type=%-2d value=%s\n", $x->[0], $x->[2], $x->[1];
	     }
	 }

	 NetSNMP::TrapReceiver::register("all", \&my_receiver) ||
	   warn "failed to register our perl trap handler\n";

	 print STDERR "Loaded the example perl snmptrapd handler\n";

       Then, put the following line in your snmprapd.conf file:

	 perl do "/usr/local/share/snmp/mytrapd.pl";

       Start snmptrapd (as root, and the following other opions make it stay in the foreground
       and log to stderr):

	 snmptrapd -f -Le

       You should see it start up and display the final message from the end of the above perl
       script:

	 Loaded the perl snmptrapd handler
	 2004-02-11 10:08:45 NET-SNMP version 5.2 Started.

       Then, if you send yourself a fake trap using the following example command:

	 snmptrap -v 2c -c mycommunity localhost 0 linkUp ifIndex.1 i 1 \
	     ifAdminStatus.1 i up ifOperStatus.1 i up ifDescr s eth0

       You should see the following output appear from snmptrapd as your perl code gets executed:

	 ********** PERL RECEIVED A NOTIFICATION:
	 PDU INFO:
	   notificationtype		  TRAP
	   receivedfrom 		  127.0.0.1
	   version			  1
	   errorstatus			  0
	   messageid			  0
	   community			  mycommunity
	   transactionid		  2
	   errorindex			  0
	   requestid			  765160220
	 VARBINDS:
	   sysUpTimeInstance		  type=67 value=0:0:00:00.00
	   snmpTrapOID.0		  type=6  value=linkUp
	   ifIndex.1			  type=2  value=1
	   ifAdminStatus.1		  type=2  value=1
	   ifOperStatus.1		  type=2  value=1
	   ifDescr			  type=4  value="eth0"

EXPORT
       None by default.

       # =head2 Exportable constants

       #   NETSNMPTRAPD_AUTH_HANDLER #	 NETSNMPTRAPD_HANDLER_BREAK #	NETSNMPTRAPD_HANDLER_FAIL
       #   NETSNMPTRAPD_HANDLER_FINISH #   NETSNMPTRAPD_HANDLER_OK #   NETSNMPTRAPD_POST_HANDLER
       #   NETSNMPTRAPD_PRE_HANDLER

SEE ALSO
       NetSNMP::OID, NetSNMP::ASN

       snmptrapd.conf(5) for configuring the Net-SNMP trap receiver.

       snmpd.conf(5) for configuring the Net-SNMP snmp agent for sending traps.

       http://www.Net-SNMP.org/

AUTHOR
       W. Hardaker, <hardaker@users.sourceforge.net>

COPYRIGHT AND LICENSE
       Copyright 2004 by W. Hardaker

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

perl v5.16.3				    2012-10-09				  TrapReceiver(3)
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