SSH – Tunnel Without Shell on SSH Server

sshssh-tunneling

I have to set up a tunnel between two hosts.

For this I use ssh in this way:

ssh -L MY_LOCAL_PORT:FOREIGN_ADDRESS:FOREIGN_PORT MYUSER@SSH_SERVER

after that, I log in to my SSH_SERVER.

How can I avoid this feature?!
I have only to set up a tunnel. I don't have to login into my SSH_SERVER…

I've tried the -N option, but it kept my shell busy.

Best Answer

As said in other posts, if you don't want a prompt on the remote host, you must use the -N option of SSH. But this just keeps SSH running without having a prompt, and the shell busy.

You just need to put the SSH'ing as a background task with the & sign :

ssh -N -L 8080:ww.xx.yy.zz:80 user@server &

This will launch the ssh tunnelling in the background. But some messages may appear, especially when you try to connect to a non-listening port (if you server apache is not launched). To avoid these messages to spawn in your shell while doing other stuff, you may redirect STDOUT/STDERR to the big void :

ssh -N -L 8080:ww.xx.yy.zz:80 user@server >/dev/null 2>&1 &

Have fun with SSH.

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SSH HTTP Tunnelling

The PermitOpen accepts any when its the only argument. Meaning it accepts PermitOpen any.
The only way I can think of to do this would be to use an iptables rule.

iptables -I OUTPUT -p tcp ! --dport 80 -m owner --uid-owner 1000 -j REJECT

This would reject any outbound traffic from user with UID=1000 that isn't going to port 80

SFTP – How to Use SFTP Over Reverse SSH Tunnel

First, this is a prerequesite (at least for me): Remote desktop over SSH reverse tunnel to replace TeamViewer

The reverse SSH tunnel looks like this:

laptop(SFTP client)--->nat--->middleman<--nat<--desktop(SFTP server)

On laptop edit ~/.ssh/config and add this:

Host SftpToDesktop
  HostName localhost
  Port %p
  User admin
  PasswordAuthentication no
  IdentityFile ~/.ssh/my_id_rsa

Then, with an existing SSH leg from laptop to middleman established already (as per above link), do the following:

$ ssh -fNL 1234:localhost:1234 -i ~/.ssh/some_id_rsa admin@middleman.com

Finally, open Dolphin (if using KDE like me) and enter this location:

sftp://SftpToDesktop:1234

Best Answer

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SSH HTTP Tunnelling

SFTP – How to Use SFTP Over Reverse SSH Tunnel

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