Symantec Private Branch Exchange (PBX) is a common Symantec component. PBX uses socket passing to reduce the number of ports that are required to be open across a firewall. PBX uses a paradigm similar to a telephone switchboard, in which calls placed to a switchboard are redirected to a known extension. In the PBX exchange, client connections that are sent to the exchange's port are redirected to an extension that is associated with the Management Server. This process multiplexer runs on the Management Server, Control Hosts, and Standard Agents.