D-Link DFL-2500 - Manual (Page 52)

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 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 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
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 D-Link Firewall. For more information on how service objects are being
used wit IP rules, see Section 3.5, “The IP Rule Set”.
A large number of Service objects come pre-defined with NetDefendOS. These include common
services such as HTTP, FTP, Telnet and SSH. Pre-defined Services can be used and also modified
just like user-defined Services. However, it is recommended 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 Comments
------------ --------------------------------------------------
all_services All ICMP, TCP and UDP services
all_tcpudp All TCP and UDP services
ipsec-suite The IPsec+IKE suite
l2tp-ipsec L2TP using IPsec for encryption and authentication
l2tp-raw L2TP control and transport, unencrypted
pptp-suite PPTP control and transport
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 Value
3.2. Services Chapter 3. Fundamentals
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