Introduce '-k' parameter that overwrites the -e parameter (if given) and
uses the IP for the external connection that corresponds to the current client
connection. The benefit arises when the parameter '-i0.0.0.0' or '-i::' in case
of IPv6 is set. This allows the entire range configured as local on the system
to receive connections and establish connections to the target server using the
IP address to which the client connected.
Note: This feature is not applicable for Windows.