Red Hat Enterprise Linux 5 Administration Unleashed

494CHAPTER 24Configuring a Firewallu32Extract quantities of up to 4 bytes from a packet, AND them with specific masks,shift them by defined amounts, and test whether the results are in a definedrange.udpIf -p udp is used, the following can be used:--source-port [!] :UDP source port or port range to match. The port can be the service name or aport number.--destination-port [!] :UDP destination port or port range to match. The port can be the service nameor a port number.uncleanTries to match packets that are malformed or unusual. Experimental.Using IPTables Target ExtensionsIn addition to the four predefined targets (ACCEPT, DROP, QUEUE, and RETURN), the followingtarget extensions are available:BALANCEBalance DNAT connections in a round-robin over a given range of destinationaddresses.--to-destination -Address range to round-robin.CLASSIFYSet the skb->priority value, which classifies the packet into a specific CBQ class.--set-class :Set the major and minor classes.CLUSTERIPSet up a cluster of nodes that share an IP and MAC address without an explicit loadbalancer in front of them. Connections are statically distributed between definednodes.--newCreate new cluster.