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I'm using Ccygwin on WinXP (with the bash shell). I want to SCP a file from my localhost to a remote machine -- host2. However, I can only SSH to an intermediate machine -- host1, and then from there SSH to host2. (Note, I ccan't access host2 from my localhost).

I thought tunneling was my answer, but when I try to set up a tunnel

ssh -L 9999:localhost:9998 dalvarado@host1 'ssh -L 9998:localhost:1234 -N dalvarado@host2'

But after typing this command and hitting enter, the system just hangs. What is the proper way to setup a tunnel and then SCP a file after?

Thanks, -

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Duplicate of superuser.com/questions/174160/… - see my answer below for a summary. – jmetz Aug 1 '12 at 20:51

To set up a SSH tunnel, use the following format:

ssh -L 9999:host2:22 user@host1

This command connects to host1 as user and tunnels port 9999 on the computer issuing the command to port 22 on host2. -N is optional, or you can use something like top or watch to keep the session alive if needed.

Then, simply scp to host2 on localhost:9999.

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When I run this command, am I supposed to end up getting logged in to host1? Also, after running this command, I opened another bash shell, and ran "scp hello.txt localhost:9999", but got a "ssh: connect to host localhost port 22: Connection refused" error. What am I doing wrong here? – Dave Aug 2 '12 at 13:41
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When you run this command, you will be connected to host1, yes. Your scp command syntax is incorrect though. Try this scp -P 9999 hello.txt user@localhost:/path/to/destination/file where user is the user on host2 that you want login as. – Rain Aug 2 '12 at 21:04
    
@Rain, you could put this example in the main answer ;) – dmeu Oct 26 '15 at 9:17

This has already been answered best here.

To summarize: put the following in ~/.ssh/config

Host target.machine
User          targetuser
HostName      target.machine
ProxyCommand  ssh proxyuser@proxy.machine nc %h %p 2> /dev/null

and then simply scp to target.machine any time you want to proxy via proxy.machine!

Also works for ssh, so will save you time ssh-ing to the target machine too.

Credit should go to user24925 who answered this in 2011.

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You could first scp the file to host1, like this:

scp file dalvarado@host1:.

Then do this to get it to host2:

ssh -t dalvarado@host1 'scp file dalvarado@host2:.'

The -t option to ssh forces it to allocate a pseudo-terminal, which may make it easier for scp on host1 to prompt you for a passphrase/password. If you have ssh-agent running and configured everywhere, you shouldn't be prompted for a passphrase/password.

I offer this alternative, because if you used a tunnel, you'd still need two commands: one to setup the tunnel and one to copy the file through it. This seems simpler.

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Fantastic solution!!! – Riccardo Apr 17 at 20:54

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