TUNNEL parameter    ==  TUNNEL=tunnelType:script
        tunnelType  ==  tty7
                    --  default: none

If specified, communication with an upstream DeleGate will be tunneled via the standard input/output of the command. The tunnel can be made of any kind of channel, a raw serial line for example, as long as it provides bi-directional transmission on it. Possibly it may be the channel to the DeleGate which will be invoked from inetd at remote host.

Currently, the tunnelType must be "tty7" which means transmission between DeleGates is done in 7bits stream. When the type is "tty7", how the TUNNEL is established is described in the specified SHIO-script file. See "src/sample.shio" in the distribution package. The name of a script file must be specified either in absolute path, or in relative file name which will be retrieved in LIBPATH. The upstream DeleGate for TUNNEL must be invoked with SERVER="tunnel1".

Example: make a tunnel without login dialogue

TUNNEL=tty7:tunnel.shio
[content of tunnel.shio]
o rsh host delegated SERVER=tunnel1\n
i READY\r\n
=

Example: make a tunnel with login dialogue
TUNNEL=tty7:tunnel.shio
[content of tunnel.shio]
o telnet hostname\n
i login:
o username\n
i Password:
o password\n
i %
o delegated SERVER=tunnel1 \n
i READY\r
i \n
=

As shown in above examples, the first line in a SHIO-script file is expected to be a shell command like "o command\n" to establish a connection to a remote server. Another way to establish a connection is putting "c host:port" on the first line. No shell nor shell command is invoked in this case.