D-Link DFL-800-AV-12 User Manual - Page 53
TCP and UDP Based Services, TCP/UDP Service, mmm-nnn
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3.2.2. TCP and UDP Based Services Chapter 3. Fundamentals Name: DestinationPorts: Type: SourcePorts: PassICMPReturn: ALG: MaxSessions: Comments: echo 7 TCPUDP (TCP/UDP) 0-65535 No (none) 1000 Echo service Web Interface 1. Go to Objects > Services 2. Select the specific service object in the grid control. 3. A grid listing all services will be presented. 3.2.2. TCP and UDP Based Services Most applications are using TCP and/or UDP as transport protocol for transferring application data over IP networks. TCP (Transmission Control Protocol) is a connection-oriented protocol that, among other things, includes mechanisms for reliable transmission of data. TCP is used by many common applications, such as HTTP, FTP and SMTP, where error-free transfers are mandatory. For other types of applications where, for instance, performance is of great importance, such as streaming audio and video services, UDP (User Datagram Protocol) is the preferred protocol. UDP is connection-less, provides very few error recovery services, and give thereby much lower overhead traffic than when using TCP. For this reason, UDP is used for non-streaming services as well, and it is common in those cases that the applications themselves provide the error recovery mechanisms. To define a TCP or UDP service in the D-Link Firewall, a TCP/UDP Service object is used. This type of object contains, apart from a unique name describing the service, also information on what protocol (TCP, UDP or both) and what source and destination ports are applicable for the service. Port numbers can be specified in several ways: Single Port Port Ranges Multiple Ports and Port Ranges For many services, a single destination port is sufficient. HTTP, for instance, uses destination port 80 in most cases. SMTP uses port 25 and so on. For these types of Service, the single port number is simply specified in the TCP/UDP Service object. Some services use a range of destination ports. As an example, the NetBIOS protocol used by Microsoft Windows uses destination ports 137 to 139. To define a range of ports in a TCP/UDP Service object, the format mmm-nnn is used. A port range is inclusive, meaning that a range specified as 137-139 covers ports 137, 138 and 139. Multiple ranges or individual ports may also be entered, separated by commas. This provides the possibility to cover a wide range of ports using only a single TCP/UDP Service object. For instance, all Microsoft Windows networking can be covered using a port definition specified as 135-139,445. HTTP and Secure HTTP (HTTPS) can be covered by stating destination ports 80,443. 53