# Configuring Protocol Agents

Protocol Agents are represented in the SMC Client by Protocol elements that have Protocol Agent as their type. Other Protocol elements are of the type Protocol Tag.

Figure: Using Protocol Agents

You do not add Protocol Agent elements directly to policies. You select Protocol Agents in custom Service elements that you create. The custom Service elements are used in Access rules. Whenever traffic matches a rule that contains a Service element with an associated Protocol Agent, the Protocol Agent is automatically activated.

All Protocol Agents are default elements, and you cannot change them or add any new ones. There are also default Service elements for most supported protocols that you can use to activate the Protocol Agents. However, some Protocol Agents have parameters and options you can set by creating customized Services.