SSH jump host

An alternative to SSH tunneling to access internal machines trough gateway is using jump hosts.

Prerequisites

 * SSH access to the gateway machine and the internal one
 * Gateway machine has Netcat installed

Usage
If usernames on machines differ, specify them:

You can give also port numbers if needed:

It works with scp command, too:

Tips
To ease the connecting even further:
 * Set these commands as shell aliases
 * To avoid typing passwords use OpenSSH keys

Multiple jumps
The same syntax can used to make jumps over multiple machines:

Links

 * SSH through jump hosts