scp file to remote server via tunnel using identity file

Question

I'm wanting to scp a file from my local machine to a remote server, using an intermediary tunnel. I've tried a few options already suggested, but none seem to work.

Breakdown: local machine

• The file to copy is called localfile.txt
• ssh connection to intermediary machine already exists, and is being re-used via ControlPath/ControlMaster

intermediary machine

• The identity to use to log in to the destination server is in ~/.ssh/identityfileforremotemachine

remote machine

• The destination will be at /home/username/remotefile.txt

I feel like I'm almost there and missing something

Answer 1

You didn't say what commands you tried, but any openssh >= 7.3, the following is almost certain to work, though you will first need to tear down the existing control master using ssh me@internediate -O exit.

ssh -i .ssh/blahblah -J me@intermediate me@finaldestination

See https://security.stackexchange.com/a/223005/88917 for some explanation of that -J

Answer 2

Create a tunnel from your local machine to the remote machine via the intermediate machine. The local machine will create an SSH session that will bind a TCP tunnel from port 2222 on your local machine to port 22 on the remote machine. You can then ssh/scp over the tunnel to achieve the copy.

1. Setup tunnel: From local machine:

   ssh -L 2222:remote_machine:22 -N user@intermediate_machine

2. Copy over tunnel

   a. Create a new terminal/tab/shell on your local machine:

   scp -P 2222 localfile.txt remote_user@localhost:remotefile.txt