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#!/usr/bin/perl -w # # File: scandns.pl # Summary: dns cleanup tool # # Author: Jon Schatz # E-Mail: jon@divisionbyzero.com # Org: # # Orig-Date: 22-Mar-00 at 13:30:53 # Last-Mod: 19-Jun-00 at 16:24:42 by # # This program is free software; you can redistribute it and/or mod +ify it # under the terms of the GNU General Public License as published # by the Free Software Foundation; either version 1, or (at your op +tion) # any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See either # the GNU General Public License or the Artistic License for more d +etails. # # # $Source: /home/jschatz/.cvs/el/file-hdr/hdr.perl,v $ # $Date: 1999/12/23 00:06:23 $ # $Revision: 1.1.1.1 $ # $Author: tkunze $ # $State: Exp $ # $Locker: $ # # -*- EOF -*- use IO::Socket; use Net::Netmask; use strict; my ($network)=@ARGV; #separate the netmask from the network my ($ip_address,$netmask) = split /[\/||:]/ , $network; my $address; &usage unless ($ip_address); #complain if @ARGV was incorrect &badip unless (&validip($ip_address)); #copmlain if $ip_address is inv +alid #complain if $netmask is bad. unfortunately Net::Netmask only warns if + it's #given an invalid netmask. I'm working on a patch so that the module w +ill #be smart enough to return something useful when it cant parse the net +mask. &badnet unless (&validnet($netmask)); #if the netmask is given as a netmask (ie, 255.255.255.0 as opposed to + CIDR # notation (/24)), then ditch the "/" since Net::Netmask isn't smart e +nough # to do that either. $network=~s/\//:/ if (validip($netmask)); #create the netmask object (my $obj=Net::Netmask->new ($network)) or die "Invalid address / netma +sk\n"; #return an array of all addresses in the given network my (@addresses)=$obj->enumerate(); foreach $address (@addresses) { &checkdns($address); } #the good stuff sub checkdns { my ($ip_address)=@_; my ($packed_ip_address)=&get_packed_ip($ip_address); my ($hostname)=gethostbyaddr($packed_ip_address, AF_INET); if (! $hostname) { &no_ptr("$ip_address"); return; } my $reverse_packed_ip_address; $reverse_packed_ip_address=gethostbyname($hostname); if (length($reverse_packed_ip_address)!=4) { &no_a("$ip_address","$hostname"); return; } my ($reverse_ip_address)=inet_ntoa($reverse_packed_ip_address); if ($reverse_ip_address ne $ip_address) { print("$ip_address => $hostname => $reverse_ip_address \n"); } else { print("$ip_address => $hostname \n"); } } sub no_ptr { my ($ip_address)=@_; print "$ip_address => no PTR record\n"; return; } sub no_a { my ($ip_address, $hostname)=@_; print "$ip_address => $hostname => $hostname has no A record\n"; return; } sub badip { print "$ip_address is an invalid address.\n"; exit 1; } sub badnet { print "/$netmask is an invalid netmask.\n"; exit 1; } sub usage { print "Usage: scandns.pl <address>[/netmask]\n"; exit 1; } sub validnet { my ($netmask)=@_; return(1) if (validip($netmask)) ; return(1) if (($netmask>=0)&&($netmask<=32)); } #this is an ip checker that seems simpler to me than the enormous rege +x in #the cookbook. since it's only executed twice, it's probably not gener +ating #that much overhead. sub validip { my ($ip)=@_; my $x; foreach ($ip=~/^(\d+)\.(\d+)\.(\d+)\.(\d+)$/){ $x++ if(($_>=0)&&($_<=255)); } return($x==4); } sub get_packed_ip { my ($ip)=@_; chomp $ip; my $a; my $b; my $c; my $d; ($a, $b, $c, $d)=split(/\./,$ip); my $packed_ip=pack "C4","$a","$b","$c","$d"; return $packed_ip; } sub bin2dec { my $str= unpack("B8", pack("N", shift)); $str=~s/^0+(?=\d)//; return $str; } sub dec2bin { return unpack("N",pack("B8", substr("0"x 8, -8))); }

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