Sometimes, firewalls block a connection setup to a well known IP address. When using the resolve mechanisms it is assumed that the information — e.g. in /etc/hosts, name servers, etc. — is maintained, accessible, trusted, and valid.

If both methods fail, a look at the actual IP configuration might help. As a (okay, maybe not the very) last resort, esp. when multiple interfaces and IPMP is concerned, examining the output of /sbin/ifconfig -a (*NIX), or ipconfig /all (WIN*) might work to reveal the interfaces currently plumbed and configured. At least the OS's tool which is responsible to configure the IPs should be able to give a reliable answer. The fragile part is to rely on the outputs layout.
You might need to change the locale language (e.g. LANG, LC_ALL) beforehand.

Illustrative code that was tested on Solaris 10, openSUSE 10.2, and OS X: 
#!/usr/bin/perl
use strict;
use Data::Dumper;

my $interface;
my %IPs;

foreach ( qx{ (LC_ALL=C /sbin/ifconfig -a 2>&1) } ) {
        $interface = $1 if /^(\S+?):?\s/;
        next unless defined $interface;
        $IPs{$interface}->{STATE}=uc($1) if /\b(up|down)\b/i;
        $IPs{$interface}->{IP}=$1 if /inet\D+(\d+\.\d+\.\d+\.\d+)/i;
}

print Dumper(\%IPs);

__END__
$VAR1 = {
          'qfe0' => {
                      'IP' => '10.0.0.32',
                      'STATE' => 'UP'
                    },
          'qfe1' => {
                      'IP' => '10.0.0.33',
                      'STATE' => 'UP'
                    },
          'hme0' => {
                      'IP' => '10.0.0.14',
                      'STATE' => 'DOWN'
                    },
          'lo0' => {
                     'IP' => '127.0.0.1',
                     'STATE' => 'UP'
                   }
        };

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In reply to Re: How do I get the local internet IP address? by Perlbotics
in thread How do I get the local internet IP address? by Anonymous Monk

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