# Creating custom Service elements with Protocol Agents

In addition to default Service elements that are associated with specific Protocol Agents, you can create custom Services.

There are default Service elements that link to Protocol Agents. These default Services can be used directly in the Access rules. However, the default Services do not allow you to change the default parameters of Protocol Agents that have configurable parameters.

If you want to change the way a Protocol Agent behaves, create a custom Service and attach the correct Protocol Agent to that Service. The Service element contains the identifying information, such as a port number, that determines which traffic the Service matches. In most cases, the identifying information makes sure that the Protocol Agent is not applied to the wrong type of traffic.