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#!/usr/local/bin/perl -w
###
### Listen for SNMP traps, decode and print them
### Simple example for a trap listener program.
###
### To make this useful, you should probably add some filtering
### capabilities and trap-specific pretty-printing.
###
package main;
use strict;
use SNMP_Session;
use SNMP_util;
use BER;
use Socket;
### Forward declarations
sub print_trap ($$);
sub usage ($ );
sub print_ip_addr ($ );
sub pretty_addr ($ );
sub hostname ($ );
sub fromOID ($ );
sub fromOID_aux ($$);
sub really_pretty_oid ($);
my $port = 162;
my $print_community = 0;
my $print_port = 0;
my $print_hostname = 1;
register_pretty_printer {BER::object_id_tag(), \&really_pretty_oid};
while (defined $ARGV[0] && $ARGV[0] =~ /^-/) {
if ($ARGV[0] eq '-p') {
shift @ARGV;
usage (1) unless defined $ARGV[0];
$port = $ARGV[0];
usage (1) unless $port > 0 && $port < 65536;
} elsif ($ARGV[0] eq '-h') {
usage (0);
exit 0;
} else {
usage (1);
}
}
snmpLoad_OID_Cache($SNMP_util::CacheFile);
die unless SNMP_util::toOID("mib-2") eq SNMP_util::toOID ("1.3.6.1.2.1");
%SNMP_util::revOIDS = reverse %SNMP_util::OIDS unless %SNMP_util::revOIDS;
my $session = SNMPv2c_Session->open_trap_session ($port)
or die "couldn't open trap session";
$SNMP_Session::suppress_warnings = 1; # We print all error messages ourselves.
my ($trap, $sender, $sender_port);
while (($trap, $sender, $sender_port) = $session->receive_trap ()) {
my $now_string = localtime time;
print "$now_string ";
print pretty_addr (inet_ntoa ($sender));
print ".$sender_port" if $print_port;
print "\n";
print_trap ($session, $trap);
}
1;
sub print_trap ($$) {
my ($this, $trap) = @_;
my ($encoded_pair, $oid, $value);
my ($community, $ent, $agent, $gen, $spec, $dt, $bindings)
= $this->decode_trap_request ($trap);
if (defined $community) {
my ($binding, $prefix);
if (defined $community) {
print " community: ".$community."\n"
if $print_community;
if (defined $ent) {
## SNMPv1 Trap
print " enterprise: ".BER::pretty_oid ($ent)."\n";
print " agent addr: ".inet_ntoa ($agent)."\n";
print " generic ID: $gen\n";
print " specific ID: $spec\n";
print " uptime: ".BER::pretty_uptime_value ($dt)."\n";
}
## Otherwise we have an SNMPv1 Trap which basically just
## consists of bindings.
##
$prefix = " bindings: ";
while ($bindings) {
($binding,$bindings) = decode_sequence ($bindings);
($oid,$value) = decode_by_template ($binding, "%O%@");
$oid = fromOID (BER::pretty_oid ($oid));
print $prefix.$oid.": ".pretty_print ($value)."\n";
$prefix = " ";
}
} else {
warn "decoding trap request failed:\n".$SNMP_Session::errmsg;
}
} else {
warn "receiving trap request failed:\n".$SNMP_Session::errmsg;
}
}
sub usage ($) {
warn <<EOM;
Usage: $0 [-p port]
$0 -h
-h print this usage message and exit.
-p port Select the UDP port on which the program will listen
for SNMP traps. The default port is 162.
EOM
exit (1) if $_[0];
}
sub pretty_addr ($ ) {
my ($addr) = @_;
my ($hostname,$aliases,$addrtype,$length,@addrs)
= gethostbyaddr (inet_aton ($addr), AF_INET);
$hostname ? $hostname." [".$addr."]" : $addr;
}
sub hostname ($ ) {
my ($addr) = @_;
my ($hostname,$aliases,$addrtype,$length,@addrs)
= gethostbyaddr (inet_aton ($addr), AF_INET);
$hostname || "[".$addr."]";
}
sub fromOID ($ ) {
my ($oid) = @_;
return fromOID_aux ($oid, '') || $oid;
}
sub fromOID_aux ($$) {
my ($pref, $suf) = @_;
while (1) {
return $SNMP_util::revOIDS{$pref}.$suf if exists $SNMP_util::revOIDS{$pref};
return undef unless $pref =~ /(.*)(\.[0-9]+)$/;
$pref = $1; $suf = $2.$suf;
}
}
sub really_pretty_oid ($) {
fromOID (BER::pretty_oid ($_[0]));
}
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