DokuWiki » Infrastructure » Operating System » CentOS 8

h1. ssh

*ssh* is installed by default

h2. basic ssh usage

the most *nix-style way of getting help for @ssh@ is @man ssh@. 

I assume that the @ssh@ port is @22@ and the involved firewalls are setup accordingly.

<pre><code class="bash">

ssh user@example.com

</code></pre>

h2. ssh usage through another machine

What if you can't reach a machine directly but through a machine in between?

Of course you could @ssh@ twice, more compact form is:

<pre><code class="bash">

ssh -t user@reachable ssh user@unreachable

</code></pre>

h2. X-session access

<pre><code class="bash">

ssh -X user@example.com

</code></pre>

starting a X-program inside the remote shell will bring up a local X-window.

<pre><code class="bash">

baobab

</code></pre>

h2. Port forwarding to local machine

the following command will forward port 3390 (e.g. @vrpd@) on @example.com@ to local 3501.

This is useful when a given port is only accessible local on a remote machine but not accessible from outside.

<pre><code class="bash">

ssh -L 3501:localhost:3390 user@example.com

</code></pre>

now you can connect to the e.g. remote @vrdp@-session by simply on your local machine.

<pre><code class="bash">

rdesktop-vrdp -kde localhost:3501

</code></pre>

h2. "dynamic tunnel port" for use as socks.proxy

sometimes a VPN is kind of an overkill, so if you only need to access local http-ressources from outside and can establish an SSH-connection from outside, this is a nice solution.

<pre><code class="bash">

ssh -N -D2000 user@example.com

</code></pre>

The parameter -N prevents an interactive shell, the parameter -D defines the local port for the dynamic tunnel. This port should be chosen above 1023, so you don't need root-access.

!Firefox_SocksProxy_settings.png!