#!/usr/local/bin/perl
#!/usr/bin/perluse strict;use warnings;require 'sys/ioctl.ph';use Socket;my %interfaces;my $max_addrs = 30;socket(my $socket,AF_INET, SOCK_DGRAM, 0) or die "socket: $!";{    my $ifreqpack = 'a16a16';my $buf = pack($ifreqpack, '', '') x $max_addrs;my $ifconf = pack('iP', length($buf), $buf);# This does the actual workioctl($socket, SIOCGIFCONF(), $ifconf) or die "ioctl: $!";my $len = unpack('iP', $ifconf);substr($buf, $len) = '';%interfaces = unpack("($ifreqpack)*", $buf);unless (keys(%interfaces) < $max_addrs) {# Buffer was too small$max_addrs += 10;redo;}}for my $addr (values %interfaces) {$addr = inet_ntoa((sockaddr_in($addr))[1]);}