Perl: Help with Net::Nslookup script

[98cwitr]

It returns the same IP over and over. This is my first perl script ever :D



use Net::Nslookup;
open (FILE, 'list.txt');
open (MYFILE, '>>dnsResults.csv');
foreach $record (<FILE>) {
my $r = null;
my $r = nslookup "$record";
print MYFILE "$record,$r \n";
}
close (MYFILE, 'dnsResults.csv');

[98cwitr]

inside test.txt I have

www.google.com (http://www.google.com)
www.yahoo.com (http://www.yahoo.com)
127.0.0.1

Only thing returned is 127.0.0.1

nameserver in resolv.conf is 8.8.8.8...bash works fine :(

use Net::Ping;
open (FILE, 'test.txt');
foreach $record (<FILE>) {
#print "ping $record \t";
$p=Net::Ping->new();
my $ping = $p->ping($record, 2);
if($ping) {print $record; };
}

[Habitual]

a post at here (http://www.perlmonks.org/?node_id=5968) says Just a warning: per Paul Vixie, nslookup is broken. Use dig (http://www.perlmonks.org/?node_id=6148)
having spent ALL day banging on dns and zone edits, I banged this script out.


vi checkdns.pl and add

#!/usr/bin/perl
$file=$ARGV[0];
chomp($file);
@list = `cat $file`;

$filedns=$ARGV[1];
chomp($filedns);
@listdns = `cat $filedns`;

foreach $dns(@listdns) {
chomp($dns);
print "\n--------------\n$dns\n";

for ($count = 2; $count >= 1; $count--) {
foreach $domain(@list) {
chomp($domain);
$ns = `dig $domain +short`;
chomp($ns);
$ns =~s/\n/\t/g;
print "$domain\t$ns\n";
}

}

}

Save it and exit the editor. make it executable using
chmod 700 checkdns.pl

Put a list of the domains in domains.txt.
Save and exit domains.txt
Put a list of dns servers in dnsservers.txt to check against (I used IPs in case RDNS is NOT set...)
save and exit dnsservers.txt

Now the Magic:

checkdns.pl domains.txt dnsservers.txt

I didn't author it, I found it and modified it (I removed "$dns" in $ns = `dig $dns $domain +short`;) because I only wanted the host and the A Record from all the nameservers.

I really hope this alternative can benefit you as it did me.

[trent.josephsen]

Habitual, the post you linked to is from 2000.

I tried to install Net::Nslookup from CPAN to see if I could replicate the problem, but the automated tests seem to depend on www.boston.com being found somewhere it isn't (at least not for me). I don't have the patience to fiddle with CPAN tonight, but I'll toss some advice your (OP's) way anyway:

1_ Always use strict and use warnings. Your first attempt has several problems that one or both of these would complain about. I don't think any of those problems are what you're actually wondering about here, but it can't hurt.

2_ Put code in [code] tags when you post it on this forum -- just makes it easier to read.

3_ It's normally better to use while instead of for(each) to iterate over a file in Perl. Not a big deal but you might want to get into the habit. Explanation (http://stackoverflow.com/questions/585341/whats-the-difference-between-it)

4_ Have you done `perldoc Net::Nslookup` and are you sure you're using it the right way? Most of the online examples I found seemed to call it with keyword arguments (e.g. domain => "google.com", not just "google.com").

Also note that Google doesn't always respond to plain pinging -- not sure why that is but it's true. If you use Net:: Ping you may want to use other domains for testing purposes. Universities are usually good.

[drmrgd]

I tried playing with Net::Nslookup and couldn't get it to install either. Seems there's an issue with this module. However, there's another one that might do what you're trying to do, Net::DNS::Nslookup. I just scribbled together this quickie that might do what you want:



#!/usr/bin/perl


use warnings;
use strict;
use Net::DNS::Nslookup;


my $outfile = "dnsResults.csv";
open( OUTPUT, ">", $outfile ) || die "Can't open file '$outfile' for writing: $!";

my $infile = $ARGV[0] || die "Need to enter a file with a list of IP Addresses";
open( INFILE, "<", $infile ) || die "Can't open the input file '$infile' for reading: $!";
while (<INFILE>) {
chomp;
my $dnsLookup = Net::DNS::Nslookup->get_ips( $_ );
print OUTPUT "$dnsLookup\n";
}
close( OUTPUT );
close( INFILE );

If you run it with:


perl nslookup.pl <file_with_sitenames>

the output will be (written to a file called dnsResults.csv):



www.google.com,173.194.73.147
www.google.com,173.194.73.105
www.google.com,173.194.73.106
www.google.com,173.194.73.99
www.google.com,173.194.73.103
www.google.com,173.194.73.104
www.ubuntuforums.org,91.189.94.12
www.cnn.com,157.166.240.13
www.cnet.com,64.30.224.103
www.perl.org,207.171.7.51
www.perl.org,207.171.7.41

I think that at least should give you a starting point.

[trent.josephsen]

I submitted a bug report on CPAN and Net::Nslookup has been fixed now.

The only other thing that I noticed after trying to use the module myself is that you have to chomp the input -- "www.google.com\n" won't resolve.