===== SSH =====
=== SSH port forwarding ===
== Single Local Port ==
<code>
ssh <user>@server -L <localPort>:<server>:<port>
</code>

== Dynamic Local Port ==
<code>
ssh <user>@server -D <localIP>:<localPort>
</code>

=== SSH no host check ===
<code>
ssh <user>@server -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null
</code>

=== Create SSH key pair ===
<code>
ssh-keygen -t ed25519 -C "<key comment>" -f ~/.ssh/<keyname>
</code>
<code>
-t = algorithm. Possible values: rsa, dsa, ecdsa, ed25519
-C = comment at the end of public key file
-f = filename
-b = bitrate. For rsa and ecdsa.
</code>

=== Create SSH key pair with Yubikey ===
Prerequsites:
  * openssh v8.2+
  * yubikey fw v5.2.3+
  * libfido2 lib installed on client

Check openssh version.
<code>
ssh -V
</code>

Check yubikey version.
<code>
lsusb -v 2>/dev/null | grep -A2 Yubico | grep "bcdDevice" | awk '{print $2}'
</code>

Create the key-pair
<code>
ssh-keygen -o -a 100 -t ed25519-sk -C "<key comment>" -f ~/.ssh/<keyname>
</code>

=== Change key comment ===
<code>
ssh-keygen -c -C "<key comment>" -f ~/.ssh/<keyname>
</code>

=== Change passphrase ===
<code>
ssh-keygen -p -f ~/.ssh/<keyname>
</code>

=== GIT Specify Key ===
edit //~/.ssh/config// and add section like the following
<code>
Host ssh.dev.azure.com
  HostName ssh.dev.azure.com
  IdentityFile ~/.ssh/<publicKeyFile>
  IdentitiesOnly yes
</code>

=== Redhat custom port ===
Edit ///etc/ssh/sshd_config// and add the lines (uncomment port 22) 
<code>
Port 22
Port 1234
</code>
Restart sshd to activate changes. You will not be able to use the custom port yet though as SElinux is blocking it.

== add port ==
<code bash>
semanage port -t ssh_port_t -p tcp 1234
</code>

== List ports with ==
<code bash>
semanage port -l|grep ssh_port_t
</code>