Services; Overview; Listing The Available Services; Viewing A Specific Service - D-Link NetDefend DFL-210 User Manual

3.2. Services

3.2. Services

3.2.1. Overview

A Service object is a reference to a specific IP protocol with associated parameters. A Service defin-
ition is usually based on one of the major transport protocols such as TCP or UDP, with the associ-
ated port number(s). The HTTP service, for instance, is defined as using the TCP protocol with as-
sociated port 80.
Service objects are in no way restricted to TCP or UDP; they can be used to define ICMP messages,
as well as any user-definable IP protocol.
Services are simple objects in that they cannot carry out any action in the system on their own. In-
stead, Service objects are used frequently by the various system policies. For instance, a rule in the
IP Rule-set can use a Service object as a filter to decide whether or not to allow certain traffic
through the firewall. For more information on how service objects are being used in policies, please
see Section 3.5, "The IP Rule-Set".
A great number of Service objects comes pre-defined with the NetDefendOS. These include com-
mon services such as HTTP, FTP, Telnet and SSH. These pre-defined services can be used and also
modified just like user-defined Services. However it is advisable not to make any changes to pre-
defined services, but instead create new ones with the desired parameters.
Example 3.6. Listing the Available Services
To produce a listing of the available services in the system:
CLI
gw-world:/> show Service
The output will look similar to the following listing:
ServiceGroup
Name
------------
all_services
all_tcpudp
ipsec-suite
l2tp-ipsec
l2tp-raw
pptp-suite
ServiceICMP
...
Web Interface
1. Go to Objects > Services
Example 3.7. Viewing a Specific Service
To view a specific service in the system:
CLI
gw-world:/> show Service ServiceTCPUDP echo
The output will look similar to the following listing:
Property
-----------------
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
Value
----------------
35
Chapter 3. Fundamentals