Control server port usage in rse.env

As documented in Connection flow, the client connects to a user-specific RSE server after authenticating with RSE daemon. To ensure that the RSE server connection is covered by an AT-TLS rule, you must specify in rse.env which ports can be used by RSE server. As mentioned in Defining the PORTRANGE available for RSE server of z/OS® Explorer Host Configuration Guide, RSE server does not need the port exclusively for the duration of the client connection. It is only in the time span between the server bind and the client connect that no other RSE server can bind to the port. This means that most connections use the first port in the range, with the rest of the range being a buffer in case of multiple simultaneous logons.

_RSE_PORTRANGE=8108-8118