WSM Reference Guide - WatchGuard Technologies

Transfer ProtocolsSource RoutingThe loose source route option and the strict source route option enable the source of anInternet packet to give routing information. Source routing options can be very dangerous,because an attacker could use them to masquerade as a different user. But, loose source routeoption and the traceroute tool can also help debug some unusual routing problems.Record RouteThe record route option was first used to do tests on the Internet. But, record route can recordonly ten IP addresses. On the current Internet, a typical connection can include 20 or 30different routers, making the record route option out of date.Time StampThe time stamp option measures the time for a packet to make one full cycle (source -->destination --> source). Higher level time protocols or time stamp messages do this task betterthan the time stamp option.Transfer ProtocolsThe Internet Protocol (IP) includes information kept in the transport layer. The transport layer has differentprotocols that tell how to transmit data between software applications: for example, UDP, TCP, ICMP,and others.UDPUser Datagram Protocol (UDP) is a datagram protocol that does not use connections. It is a very fast protocol,and it does not use much bandwidth or CPU. But, you cannot trust that datagrams will get to theirdestination. A software application that uses UDP must make sure that the full message gets to its destinationin the correct sequence.Characteristics of UDP include:• Frequently used for services that include the exchange of small quantities of data where sendinga datagram more than one time is not a problem.• Used for services such as time synchronization in which a missing packet does not have an effecton continued operation. Many systems using UDP send packets again at a constant rate to tellother systems about unusual events.• Frequently used on LANs. Because of its low system and bandwidth requirements, it gives a largeperformance advantage to Network File System (NFS) services users. Network File System is apopular TCP/IP service for supplying shared file systems over a network.• Gives supports to broadcasts.• Gives abstraction of ports. A connection is made of its source and destination ports and its sourceand destination IP addresses. In typical use, port numbers less than 1024 are saved for wellknownservices (destinations). The client side can use ports higher than1023 for the source of theconnection. But, this rule has many exceptions: NFS (port 2049) and Archie (port 1525) use serverports at numbers higher than1024. Some services use the same source and destination port forserver to server connections. Examples include DNS (53), NTP (123), syslog (514), and RIP (520).Reference Guide 5