SSH forwarding example

Suppose we have the following network topology: server with two interfaces 192.168.3.3 and 192.168.4.1, passthrough-pc with two interfaces: 192.168.4.2 and 128.4.1.82 and client-pc with interface 128.4.1.1. Server acts as a gateway into 192.168.3.0/24 for passthrough-pc and provides ssh at 192.168.3.3:22. We want to access that ssh from client-pc. Passthrough-pc provides ssh to client.

It's quite simple. We just need ssh port forwarding feature. Do on passthrough-pc:

ssh -4 128.4.1.82:54321:192.168.3.3:22 192.168.3.3

That's all. We done:

ssh -p 54321 -i <key> 128.4.1.82
sshfs -p54321 -o IdentityDile=<key> 128.4.1.82:/path /mountpoint