Services; Overview - 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
definition is usually based on one of the major transport protocols such as TCP or UDP, with the
associated port number(s). The HTTP service, for instance, is defined as using the TCP protocol
with associated port 80.
However, service objects are not restricted to just TCP or UDP. They can be used to define ICMP
messages, as well as a user-definable IP protocol.
Services as Objects
Services are passive objects in that they cannot carry out any action in the system on their own.
Instead, service objects are used frequently in the various security policies defined by rule sets. For
example, 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 NetDefend Firewall. For more information on how service objects are
being used with IP rules, see Section 3.5, "The IP Rule Set".
Predefined Services
A large number of service objects come predefined with NetDefendOS. These include common
services such as HTTP, FTP, Telnet and SSH. Predefined services can be used and also modified
just like user-defined services. However, it is recommended NOT to make any changes to predefined
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:
Command-Line Interface
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
Name
------------
all_icmp
"
"
Web Interface
1. Go to Objects > Services
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
Comments
--------------------------------------------------
All ICMP services
80
Chapter 3. Fundamentals