Mirne upravene reseni Lukase Navratila:

egrep '^((1[0-9]{2}|2[0-4][0-9]|25[0-5]|[0-9]{1}|[1-9][0-9])\.){3}(1[0-9]{2}|2[0-4][0-9]|25[0-5]|[0-9]{1}|[1-9][0-9])$'