#!/usr/bin/perl -w  

# SNMP::Extension::PassPersist is required.
# This is in the package libsnmp-extension-passpersist-perl on Debian and Ubuntu
# Usage : Copy the script to /usr/bin/ifAlias_persist and add to /etc/snmp/snmpd.conf 
# pass_persist .1.3.6.1.2.1.31.1.1.1.18 /usr/bin/ifAlias_persist

use strict;
use SNMP::Extension::PassPersist;


# create the object
my $extsnmp = SNMP::Extension::PassPersist->new(
    backend_collect => \&update_tree,
    idle_count      => 10,      # no more than 10 idle cycles
    refresh         => 60,      # refresh every 60 sec
);

# run the program
$extsnmp->run;

sub update_tree {
    my ($self) = @_;


	my $Base = ".1.3.6.1.2.1.31.1.1.1.18";
	my @iface_list = `/sbin/ip l | /bin/grep mtu`;
	my @desc_list = `/bin/vtysh -c "show interface description"`;
	my $type = "string";
	my $description = "";

	foreach my $row (@iface_list){
		my @split = split(": ", $row);
		my @int = split("@", $split[1]);
		my @desc = grep { /^$int[0]\ / } @desc_list;
		my @onlydesc = split(' ', $desc[0], 4);
		chomp($onlydesc[3]);
		if ( $onlydesc[3] ne "" ) {
			$description = $onlydesc[3];
		} else {
			$description = $split[1];
		}
		chomp($description);
		my ($key, $value) = ("$Base.$split[0]",$description);
		$self->add_oid_entry($key,$type,$value);
	}
	# $extsnmp->dump_oid_tree();
	
}