SSH

 SSH (Secure Shell) is a network protocol that enables secure remote connections between two systems.

1. Connect remote machine using IP address or machine name: The remote server can be connected with local user name using either host name or IP address

ssh <host-name> or <ip-address>

Example:
ssh 192.111.66.100
ssh test.remoteserver.com

2. Connect remote machine using username: It is also possible specify a user for an SSH connection.

ssh username@hostname_or_ip-address

Example:
ssh john@192.0.0.22
ssh john@test.remoteserver.com

3. :Connect remote machine using custom port By default, the SSH server listens for a connection on port 22. But you can also specify the custom port.

ssh <host-name> or <ip-address> -p port_number

Example:
ssh test.remoteserver.com -p 3322

4. Generate SSH keys using keygen: SSH Keygen is used to generate a key pair which consists of public and private keys to improve the security of SSH connections.

ssh-keygen -t rsa

5. Copying SSH keys to servers: For SSH authentication, ssh-copy-id command will be used to copy public key(id_rsa.pub) to server.

ssh-copy-id hostname_or_IP

6. Copy a File Remotely over SSH: SCP tool is used to securely copy files over the SSH protocol.

scp fileName user@remotehost:destinationPath

Example:
scp test.txt test@10.0.0.64:/home/john/Desktop

7. Edit SSH Config File SSH server options customized by editing the settings in sshd_config file.

sudo vim /etc/ssh/sshd_config

8. Run commands on a remote server SSH commands can be executed on remote machine using the local machine.

ssh test.remoteserver.com mkdir NewDirectoryName // Creating directory on remote machine

9. Restart SSH service: You need to restart the service in Linux after making changes to SSH configuration.

sudo ssh service restart
(or)
sudo sshd service restart