ctrl as tcp forwarder for ssh

ctrl can be used to forward a TCP stream between two nodes. The Individual TCP packet will be read from a TCP listener on a node, put into a standard ctrl message, the message are then sent to the destination node using NATS PUB/SUB where the TCP packet is extracted, and written to the TCP connection.

In the follwing example we have two nodes, where we can think of node1 as the local node running on your computer, and node2 are the remote node running on a server somewhere.

We want to connect with ssh to node2, but it is not directly available from the network where the local node1 resides, so we use ctrl as a proxy server and forward the ssh tcp stream.

Steps

1. Create the message with forwarding details, and copy iy into node1's readfolder.

---
- toNodes:
    - node1                 # The source node where we start the tcp listener
  method: portSrc           # The ctrl tcp forward method
  methodArgs:
    - node2                 # The destination node who connects to the actual endpoint
    - 192.168.99.1:22       # The ip address and port we want to connect to from endpoint.
    - :10022                # The local port to start the listener on node1
    - 30                    # How many seconds the tcp forwarder should be active
  methodTimeout: 30         # Same as above, but at the method level. Set them to the same.
  replyMethod: console      # Do logging to console on node1
  ACKTimeout: 0             # No ACK'in of messages. Fire and forget.

1. On node1 a process with a TCP listener will be started at 0.0.0.0:10022.

2. The process on node1 will then send a message to node2 to start up a process and connect to the endpoint defined in the methodArgs.

3. The forwarding are now up running, and we can use a ssh client to connect to the endpoint which are now forwarded the node1 on port 10022.

ssh -p 10022 user@localhost

The forwarding will automatically end after the timeperiod specified, which in this example is 30 seconds.