About SSH Tunneling

RedNeck-LQ · 07-24-2011, 07:26 PM

Hey,

I want to do ssh tunneling. I went to youtube and saw some videos on the subject.

I'm a bit confused...

Some people use the -L and others used -D with ssh. Do these switches do the same thing?

BTW, I edited three lines from the /etc/ssh/sshd_config file. I change the port number and I removed the hash mark from the two lines below.

AllowTcpForwarding yes
PermitTunnel yes

Is this enough to do ssh tunneling?

sysfce2 · 07-24-2011, 10:46 PM

It should do the trick. I believe -D is for establishing a local port to forward over. The -R switch will establish a port on the remote server.
Normally (assuming you are initiating the ssh connection from the machine you want to tunnel from) you will want the -D switch.

phil.d.g · 07-25-2011, 01:50 AM

Quote:

Originally Posted by man ssh

-D ...
Whenever a connection is made to this port, the connec‐
tion is forwarded over the secure channel, and the application protocol is then
used to determine where to connect to from the remote machine. Currently the
SOCKS4 and SOCKS5 protocols are supported, and ssh will act as a SOCKS server.
Only root can forward privileged ports. Dynamic port forwardings can also be
specified in the configuration file.

If you use -D then you need a SOCKS proxy aware app. For ssh you can use connect-proxy. On the plus side you don't need to set up explicit tunnels for every ssh connection you want to go through that server. You can also use it to proxy web/email/any other traffic you care through it.

-L binds a specific remote address and port to a local port. It is a little more convenient to setup, you simply connect to the local port as you would the remote one, but it is less flexible, ie you have to explicitly set up each tunnel

RedNeck-LQ · 07-25-2011, 09:34 AM

Thanks sysfce2 and phil.d.g for your feedback. I'm less confused now