$_ = '192.168.2.111';
my @l;
/^(?:([01]?\d\d?|2[0-4]\d|25[0-5])(?{push@l,$1})\.){3}([01]?\d\d?|2[0-4]\d|25[0-5])$/;
print join('-',@l,$2),"\n";
__END__
192-168-2-111