CODEWITHSUNDEEP
perliplookupnslookupreverse-dns
Joakim
Joakim

Reputation: 11978

Reverse DNS lookup in perl

How do I perform a reverse DNS lookup, that is how do I resolve an IP address to its DNS hostname in Perl?

Upvotes: 13

Views: 30594

Answers (8)

John Boone
John Boone

Reputation: 41

perl -MSocket -E 'say scalar gethostbyaddr(inet_aton("69.89.27.250"), AF_INET)'

Returns: Can't find string terminator "'" anywhere before EOF at -e line 1.

perl -MSocket -E "say scalar gethostbyaddr(inet_aton(\"69.89.27.250\"), AF_INET)"

Returns: box250.bluehost.com

I have to change the line to use double quotes and then escape out the quotes around the IP address

Upvotes: 4

Kai Carver
Kai Carver

Reputation: 2288

one-liner:

perl -MSocket -E 'say scalar gethostbyaddr(inet_aton("79.81.152.79"), AF_INET)'

Upvotes: 2

Jagmal
Jagmal

Reputation: 5966

This might be useful...

$ip = "XXX.XXX.XXX.XXX" # IPV4 address.
my @numbers = split (/\./, $ip);
if (scalar(@numbers) != 4)
{
    print "$ip is not a valid IP address.\n";
    next;
}
my $ip_addr = pack("C4", @numbers);
# First element of the array returned by gethostbyaddr is host name.
my ($name) = (gethostbyaddr($ip_addr, 2))[0];

Upvotes: 0

Jeff
Jeff

Reputation: 6707

If you need more detailed DNS info use the Net::DNS module, here is an example:

use Net::DNS;
my $res = Net::DNS::Resolver->new;

# create the reverse lookup DNS name (note that the octets in the IP address need to be reversed).
my $IP = "209.85.173.103";
my $target_IP = join('.', reverse split(/\./, $IP)).".in-addr.arpa";

my $query = $res->query("$target_IP", "PTR");

if ($query) {
  foreach my $rr ($query->answer) {
    next unless $rr->type eq "PTR";
    print $rr->rdatastr, "\n";
  }
} else {
  warn "query failed: ", $res->errorstring, "\n";
}

Original Source EliteHackers.info, more details there as well.

Upvotes: 22

Joakim
Joakim

Reputation: 11978

use Socket;
$iaddr = inet_aton("127.0.0.1"); # or whatever address
$name  = gethostbyaddr($iaddr, AF_INET);

Upvotes: 17

moritz
moritz

Reputation: 12842

If gethostbyaddr doesn't fit your needs, Net::DNS is more flexible.

Upvotes: 1

nsayer
nsayer

Reputation: 17047

There may be an easier way, but for IPv4, if you can perform ordinary DNS lookups, you can always construct the reverse query yourself. For the IPv4 address A.B.C.D, look up any PTR records at D.C.B.A.in-addr.arpa. For IPv6, you take the 128 hex nibbles and flip them around and append ipv6.arpa. and do the same thing.

Upvotes: 1

JBB
JBB

Reputation: 4861

gethostbyaddr and similar calls. See http://perldoc.perl.org/functions/gethostbyaddr.html

Upvotes: 20

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