#!/usr/bin/perl

use CGI qw/:standard/;
use Socket;

my $domain="example.com";
my ($host, $user);

my @nums = (['m', 'l'],    # 0
         ['q', 't'],    # 1
         ['x', 'd'],    # 2
         ['z', 'k'],    # 3
         ['s', 'b'],    # 4
         ['c', 'h'],    # 5
         ['r', 'n'],    # 6
         ['v', 'p'],    # 7
         ['g', 'j'],    # 8
         ['w', 'f'],    # 9
         ['a', 'e'],    # 10
         ['i', 'o'],    # 11
         ['u', '1'],    # 12
         ['2', '4'],    # 13
         ['5', '6'],    # 14
         ['9', '7']);   # 15

$host = remote_host();

if ($host !~ /^(\d{1,3}\.){3}\d{1,3}$/) {
   $host = inet_ntoa(scalar gethostbyname($host));
}

$user = "";
foreach $octet (split /\./, $host) {
    $high = $octet>>4;
    $low = $octet & 0xF;
    $user .= $nums[$high][int rand 2];
    $user .= $nums[$low][int rand 2];
}

$user = "webmaster" if (!$user);

print header;
print start_html, "E-mail me <A HREF=\"mailto:$user\@$domain\">$user\@$domain</A>", end_html;

##</code><code>##

#!/usr/bin/perl

#use CGI qw/:standard/;
use Socket;

my ($addr);

my @nums = (['m', 'l'],    # 0
         ['q', 't'],    # 1
         ['x', 'd'],    # 2
         ['z', 'k'],    # 3
         ['s', 'b'],    # 4
         ['c', 'h'],    # 5
         ['r', 'n'],    # 6
         ['v', 'p'],    # 7
         ['g', 'j'],    # 8
         ['w', 'f'],    # 9
         ['a', 'e'],    # 10
         ['i', 'o'],    # 11
         ['u', '1'],    # 12
         ['2', '4'],    # 13
         ['5', '6'],    # 14
         ['9', '7']);   # 15

my %backwards;
for ($i = 0; $i < 16; $i++) {
    $backwards{$nums[$i]->[0]} = $i;
    $backwards{$nums[$i]->[1]} = $i;
}

$addr = shift || die;

$addr =~ s/\@.*//;
if (length $addr != 8) {
   print "Bad length\n";
   exit;
}

@chars = split //, $addr;
for ($i = 0; $i < 8; $i += 2) {
    push @octets, $backwards{$chars[$i]}<<4 | $backwards{$chars[$i+1]};
}

$ip = join ".", @octets;

print "IP is $ip\n";
$host = scalar gethostbyaddr(scalar inet_aton($ip), AF_INET) || "unknown";
print "Host is $host\n";