Trampoline can be used in a service file (see listen(8)) to link
an incoming call to another address that provides the service,
typically on another machine.
Trampoline dials addr and copies data between that connection
and its own standard input and output.
The options are:
–9 The connection carries only 9P messages. In this case trampoline
will relay whole messages at a time.
Dial altaddr and relay between the two network connections, ignoring
standard input and output.
Restrict forwarding to particular machines. Netdir must be the
incoming call directory. Trampoline finds the caller's MAC address
m and checks that ndb(6) contains an entry with ether=m and the
attribute trampok. If no such entry is found, the call is rejected.
Write a protocol–specific control string opt to the connections
control file. This can be specified multiple times.
Terminates the connection after timeout milliseconds of inactivity.