Forward an FTP/SFTP connection to another server (instead of tunneling from the client)

Question

I've been accessing a server's files via Sublime SFTP.

The issue is that I need to tunnel into my destination server via a middle-man server (that I have root access to).

Client → Server A (middle-man node) → Server B (destination node)

Normally I'd use a tunneling option in the client software, but in this case Sublime doesn't seem to have that feature.

What's the best way for me to configure the middle-man server (apache) to accomplish this? (or something like it)

For example, maybe there's a way to automatically have Server A connect to Server B when the client successfully connects to a particular port?

Linuxx · Accepted Answer

With HAProxy you can create a TCP proxy to proxy the connection back to the backend server. I do this frequently.

Mora · Answer

You could use rinetd to acomplish what you want:
apt install rinetd

Then you edit /etc/rinetd.conf, and add your configuration at the end:
SERVER_A_IP SERVER_A_PORT SERVER_B_IP SERVER_B_PORT

Example:
# Server A IP: 192.168.0.1
# Server B IP: 1.2.3.4
# Listen on port 8080 on local server and redirect to 22 on remote server
# Configuration
192.168.0.1 8080 1.2.3.4 22

Finally you restart the service:
systemctl restart rinetd

And connect through SERVER A:
sftp -P 8080  user@SERVER_A_IP

billkw · Answer

I would recommend that you use SSH Tunneling.

ssh -L 9999:server_b:22 username@server_a

You'll of course also need to confirm that Server A's firewall accepts inbound TCP connections on your port of choice.

Forward an FTP/SFTP connection to another server (instead of tunneling from the client)

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