#!/usr/bin/perl###################################################### snmpqry.pl## This script uses SNMP to query an NAT gateway for# its external address. The NAT gateway must support# SNMP and MIB-II.## See COPYING for licensing information####################################################### suffix for text filesmy $cfgsuff = '';$cfgsuff = '.txt' if $ENV{'windir'} and $ENV{'comspec'};# PERL packages and optionsuse strict;use Socket;use Getopt::Std;# locate ourselvesuse vars qw($gnudipdir);use FindBin;BEGIN {  $gnudipdir = '';  if ($FindBin::Bin =~ /^(.*)\/bin$/) {    $gnudipdir = $1;  } else {    $gnudipdir = $FindBin::Bin;  }}use lib "$gnudipdir/lib";# modules for SNMP supportuse BER;use SNMP_util;# get program namemy $pgm = $0;if ($pgm =~ /^.*\/(.+?)$/) {  $pgm = $1;}# process command linesub usage {  print STDOUT <<EOQ;usage: $pgm { -h | [ -e ] host }usage: Use SNMP/MIB-2 to determine the "external" IP address of host.usage: -h: Print this usage message.usage: -e: Show detailed error messages produced by Perl SNMP routines.EOQ  exit;}use vars qw($opt_e $opt_h);if (!getopts('eh')) {  usage();}if ($opt_h) {  usage();}if (@ARGV ne 1) {  usage();}my $host = shift;# allow warnings from Perl modules?$SNMP_Session::suppress_warnings = 2 if ! $opt_e;# generate trace messages?my $trace = '';#$trace = 1;# get default gateway interface number from target hostmy ($external_if) = snmpget($host, 'ip.ipRouteTable.ipRouteEntry.ipRouteIfIndex.0.0.0.0');if (! $external_if) {  print STDERR "Could not get default gateway interface number from target host\n";  exit 1;}if ($trace) {  print STDERR "default gateway interface number from $host: $external_if\n";}# get address <=> interface number pairs from target hostmy @address_ifs = snmpwalk($host, 'ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex');if (! $address_ifs[0]) {  print STDERR "Could not get address <=> interface number pairs from target host\n";  exit 1;}if ($trace) {  print STDERR "address <=> interface number pairs from $host:\n";  foreach my $address_if (@address_ifs) {    print "  $address_if\n";  }}# scan for external interface numbermy $external_addr;foreach my $address_if (@address_ifs) {  my ($address, $ifnum) = split(/:/, $address_if);  if ($ifnum == $external_if) {    $external_addr = $address;    last;  }}if (! $external_addr) {  print STDERR "Could not find address for default gateway interface number\n";  exit 1;}# provide external addressprint "$external_addr\n";exit;