Something

#!/usr/bin/perl -w

# ytti@iki.fi

use strict;

my $hostname='foo';

while(<STDIN>) {
  chop;
  if(/^hostname (.*)/) { $hostname=$1; }
  if(/^interface (.*)/) {
    my $accept=1;
    my $ip=0;
    my $int=$1;
    if ($int=~/en-tue-tätä/) { $accept=0; }
    while(<STDIN>) {
      my $addess=0;
      last if(/^!/);
      if ($_=~/^ ip(?:v6)? address ([\d.:]+).*/) { $ip=$1; last; }
    }
    if($ip and $accept) {
      $int=~s/\//-/g;
      $int=~s/\./-/g;
      $int=~s/FastEthernet/fa/;
      $int=~s/GigabitEthernet/ge/;
      $int=~s/Loopback/lo/;
      print "$int." . lc($hostname) . " has address $ip\n";
    }
  }
}