If you need to SSH to a host but don't have direct SSH access, you can perform a reverse SSH tunnel. For this you need a host that will except inbound connections to work as a "jump host", it is possible without it, where you could SSH back to your client computer; however for the purposes of this example the setup is as follows: 1. TARGETSRV - Target host you want to connect to, you will start the SSH reverse tunnel from here.The first step is to start the SSH reverse tunnel from the TARGETSRV. Here we are creating a tunnel from port 22 on the TARGETSRV to port 19999 on the JUMPHOST over port 22 SSH. # ssh -p 22 -R 19999:localhost:22 JUMPHOST -l <user> Now SSH to the JUMPHOST from CLIENT and run the following command: ssh -p 19999 127.0.0.1 -l <user> Now you will have connected to the TARGETSRV down the reverse tunnel.Especially useful if your target host is behind a firewall where direct access is not possible. |
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