I have three machines. The local machine L, Server1 A, Server2 B.
L is able to connect to A
A is able to connect to B
L is not able to connect to B

I want to copy a file from L to B without taking the extra step to login on A for coppying the data.

Is that possible with scp? If yes, how?

1 Answer 1


L is not able to connect to B, but is B able to connect to L? You didn't say, but I will assume no.

If A is your only way to communicate between B and L then you will definitely have to log in to A at some point. And also, the data will flow through A one way or another (which might be important if A is on a slow connection).

You can establish an SSH tunnel through A in a couple of different ways to get from L to B. For example:

# From L
ssh -L 2222:B:22 -Nf A

Now add the following configuration in ~/.ssh/config on L as a convenience for connecting to B through the tunnel:

Host B
    HostName localhost
    HostKeyAlias B
    Port 2222

Then you can connect to B through the tunnel:

scp file B:

There are other options for setting up this tunnel, including tools to automatically establish the tunnel in the background.


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