--- //[[mcamav@gmail.com|Marc Verhaar]] 2021/12/19 13:46//FIXME

====== SSH tunneling: ======

===== Local portforwarding: =====

Using the ssh server as a jumphost for a service in the ssh server network:

{{:knowledgebase:linux:local_port_forwarding.jpg?direct&600|}}

We can establish these connections like this:

<code> ssh user@server -L 12345:192.168.1.200:81</code>

**This will open an SSH session and as long as it runs the tunnel is active!**

You can now open a local browser to http://localhost:12345 and it will open 192.168.1.200:81 on the network where the SSH server is located.

===== Remote portforwarding: =====
FIXME

===== Dynamic portforwarding with SOCKS proxy: =====

=== Install ''proxychains:'' ===

<code> sudo apt install proxychains -y</code>

=== Edit /etc/proxychains.conf on **client** and in the **ProxyList** section set the port: ===

<code>
[ProxyList]
# add proxy here ...
# meanwile
# defaults set to "tor"
socks5  127.0.0.1 9050</code>

**Use socks5 which supports encrypted tunnels and UDP protocol!**

=== Now we can set up the SSH tunnel: ===

<code>ssh user@server -D 9050</code>

**This will open an SSH session and as long as it runs the tunnel is active!**

=== We can now use the SSH tunnel with any application that supports SOCKS: ===

  * Webbrowsers (configure proxysettings)
  * RDP (configure proxysetting or use ''proxychains rdesktop 192.168.1.x'')
  * VNC
  * ...

Webbrowsers do support this but we need to configure the proxy configuration according to the tunnel:

{{:knowledgebase:linux:socks_proxy.jpg?direct&600|}}

=== We now can connect directly to the servers in the SSH Server network: ===


{{:knowledgebase:linux:socks_proxy_client.jpg?direct&600|}}

===== Using SSH Jumphost: =====

We can use an SSH Jumphost to connect to an SSH server:

<code>ssh user@server -J user@jumphost
example:
ssh root@192.168.1.70 -J marcv@verhaar.cc</code>

Using multiple jumphosts:

<code>

ssh user@destination -J user@jumphost1 user@jumphost2</code>

FIXME: using ssh config file for jumphosts...


===== Example config file: =====
We can create a configuration file for the ssh client which is used to define hosts, usernames, portnumbers, etc.

The file needs to be created in ~/.ssh/ thus the full path is ~/.ssh/config.
<code>
Host myserver                                      # The name you want to use to connect
  Hostname 192.168.1.10                            # The IP address the hostname needs to be translated to
  Port 22                                          # The port you want to use
  User marc                                        # The username used to set up the connection
 </code>