$.validator.addMethod( "ipv4", function( value, element ) {
return this.optional( element ) || /^(25[0-5]|2[0-4]\d|[01]?\d\d?)\.(25[0-5]|2[0-4]\d|[01]?\d\d?)\.(25[0-5]|2[0-4]\d|[01]?\d\d?)\.(25[0-5]|2[0-4]\d|[01]?\d\d?)$/i.test( value );
}, "Please enter a valid IP v4 address." );