Ssh – Port forwarding between 3 machines

port-forwardingsshssh-tunnel

I have 3 machines that are connected as a chain, A,B,C. 

 A-->B-->C

A is my machine, B is server, and C is other machine with some services and web server on it.
Because of some issues I need access from A to webserver on C (port 80),
I can use ssh to login from A to B and then from B to C, but console at this moment is too less. I need web browser, and using ssh with option -X didn't work (some issues with dbus with Firefox start).

I make port forwarding on B using classic command to forward 22 port for ssh:

ssh -L 2222:localhostB:22 user@ipC

but using same to forward port 80 didnt work:

ssh -L 8888:localhostB:80 user@ipC

I know that there is some other forwarding to make it work, but I didn't understand how and what.

I need something like this:

A --> B (frd from B:8888 to C:80) --> C (port 80 web server)

so as effect when I type ipB:8888 I will be forwarded to C:80.

Any help as explain what have to be done, or scripts with command will be appreciated. I notice from one blog that it must be done two times ssh -L forwarding done, but I didn't understand why.

Best Answer

You're on the right track.

On A:

ssh -L 8888:ipC:80 user@ipB -N

Will make the web server on C accessible via localhost:8888 on A

A bit more details at the OPs request:

I've assumed from your question that you want to access the webserver of C on A (I'm guessing you have a GUI environment on A, with a web browser).

You can't access C directly (for whatever reason), but you can access B, which in turn can access C. So we create a tunnel between A and B, asking B to attach its end of the tunnel to the webserver on C

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