D-Link DFL-260 Product Manual - Page 82
Services, 3.2.1. Overview, A Service is Passive, Predefined Services - allow ftp
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3.2. Services Chapter 3. Fundamentals 3.2. Services 3.2.1. Overview A Service object is a reference to a specific IP protocol with associated parameters. A service definition is usually based on one of the major transport protocols such as TCP or UDP which is associated with a specific source and/or destination port number(s). For example, the HTTP service is defined as using the TCP protocol with the associated destination port 80 and any source port. However, service objects are not restricted to just the TCP or UDP protocols. They can be used to encompass ICMP messages as well as a user-definable IP protocol. A Service is Passive Services are passive NetDefendOS objects in that they do not themselves carry out any action in the configuration. Instead, service objects must be associated with the security policies defined by various NetDefendOS rule sets and then act as a filter to apply those rules only to a specific type of traffic. For example, an IP rule in a NetDefendOS IP rule set has a service object associated with it as a filtering parameter to decide whether or not to allow a specific type of traffic to traverse the NetDefend Firewall. Inclusion in IP rules is one the most important usage of service objects and it is also how ALGs become associated with IP rules since an ALG is associated with a service and not directly with an IP rule. For more information on how service objects are used with IP rules, see Section 3.5, "IP Rule Sets". Predefined Services A large number of service objects are predefined in NetDefendOS. These include common services such as HTTP, FTP, Telnet and SSH. Predefined services can be used and also modified just like custom, user defined services. However, it is recommended to NOT make any changes to predefined services and instead create custom services with the desired characteristics. Custom service creation in detail later in Section 3.2.2, "Creating Custom Services". Example 3.6. Listing the Available Services To produce a listing of the available services in the system: Command-Line Interface gw-world:/> show Service The output will look similar to the following listing with the services grouped by type with the service groups appearing first: ServiceGroup Name -----------all_services all_tcpudp ipsec-suite l2tp-ipsec l2tp-raw pptp-suite Comments All ICMP, TCP and UDP services All TCP and UDP services The IPsec+IKE suite L2TP using IPsec for encryption and authentication L2TP control and transport, unencrypted PPTP control and transport ServiceICMP 82