print "What IP address do you want to allow ssh logins from? ";
    $_ = <>;
    chomp($_);
    # This method does not appear to do strict validation of IP addresses
    # While, it will check for a valod dotted quad entry, it will allow many invalid addresses.
    # See the following for additional hints:
    # http://www.perlmonks.org/index.pl?node_id=513811
    # http://www.perlmonks.org/index.pl?node=221512
    # For the time being, this is a sufficient check    
    my $allowed_ipaddr = inet_aton( $_ );
    length($allowed_ipaddr) or die "Sorry, '$_' is not a valid IP address.\n";
    $allowed_ipaddr = inet_ntoa($allowed_ipaddr); # convert to dotted quad, if necessary.
    print " You have authorized the host with IP address $allowed_ipaddr to log in via ssh.\n";