If specified together with SOCKS,
PROXY, MASTER (to chain two DeleGate),
then the communication between DeleGate is multiplexed on a single
persistent connection using SockMux.
This is useful to reduce the delay to establish many connections repeatedly
between DeleGate which are running distant from each other with long RTT.
host:port specifies the port toward which a SockMux
persistent connection is established.
The connection is established from the DeleGate with "con"
option to the DeleGate with "acc" option.
acc -- accept a SockMux connection at "host:port". con -- connect a SockMux connection to "host:port". ssl -- use SSL instead of the "Credhy" encryption.