Amer Networks E5Web GUI - Manual (Page 143)

3.3. Services
3.3.1. 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 cOS Core 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 cOS Core 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 cOS Core 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
Clavister Security Gateway. 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 3.6, “IP Rules and
IP Policies”.
Predefined Services
A large number of service objects are predefined in cOS Core. 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 3.3.2, “Creating Custom Services”.
Example 3.11. Listing the Available Services
To produce a listing of the available services in the system:
Command-Line Interface
Device:/> 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 Comments
------------ --------------------------------------------------
all_services All ICMP, TCP and UDP services
Chapter 3: Fundamentals
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