What's this?

Adapter tool that receives raw IP datagrams on an outside socket, unwraps the UDP payload and sends them to other sockets given on the command line. Conversely, data received from those other sockets is wrapped with a UDP header, and sent out the outside socket.

Example:

tunnel_inserter \
    --outside 10 --control 11 \
    --local-addr 192.168.12.1
    --remote-addr 192.168.12.2
    --local-ports 2000 2001 \
    --remote-ports 3000 3001 \
    -- \
    my_command --foo '{fd0}' --bar '{fd1}'

Causes tunnel inserter to start the executable my_command with the provided arguments above. The {fd0} and {fd1} place holders are replaced by integer unix datagram socket file descriptors opened by tunnel_inserter.

Any datagram received by tunnel_inserter on FD 10 is verified to be a raw UDP packet with source address 192.168.12.2 and destination address 192.168.12.1. If it is, then

• If the source port is 3000 and the destination port is 2000, the packet payload is sent as a datagram to my_command's fd0.
• If the source port is 3001 and the destination port is 2001, the packet payload is sent as a datagram to my_command's fd1.
• Otherwise, the packet is dropped.

Likewise, any datagram received from my_command's fd0 gets a UDP header prepended with source address 192.168.12.1, destination address 192.168.12.2, source port 2000 and destination port 3000, and is sent out on FD 10. Similarly, datagrams received on fd1 are treated the same except that the port numbers are (2001, 3001) in this case.

Notes

• Interfaces to lightway:

  • --outside: to/from the outside
  • --control: the read end of a control pipe. The tool shuts down when the write end is closed. Note: There is no --inside: This input is currently directly wired through from lightway to the tunnel inherited through tunnel_inserter; tunnel inserter does not touch it.

• Interfaces to the bitripple tunnel:

  • feedback send
  • feedback receive
  • data send
  • data receive