What is ssh Linux command?

The ssh command in Linux allows users to securely connect to a remote server. It provides a secure encrypted connection for accessing a shell session on a remote machine, transferring files, and executing commands securely.

ssh Syntax:

ssh [options] user@hostname

ssh Options:

Option	Description
-l username	Specifies the username to use for login
-p port	Specifies the port number
-i identity_file	Specifies the identity file
-c cipher_spec	Specifies the encryption cipher to use
-v	Verbose mode (increases verbosity)
-q	Quiet mode (suppresses warnings)
-Y	Enables trusted X11 forwarding

Caution

Exercise caution while using the ssh command as it allows access to remote servers and systems. Make sure you have proper authorization before connecting to a remote host.

Parameters:

Parameter	Description
user	The username used to log in to the remote host
hostname	The hostname or IP address of the remote host

ssh Command Usage Examples:

Connect to a Remote Server

ssh username@remote_server

Establishes a secure shell connection to a remote server using the specified username.

Connect to a Specific Port on a Remote Server

ssh -p port_number username@remote_server

Connects to a remote server through a specific port by specifying the port number with the -p flag.

Execute a Command on a Remote Server

ssh username@remote_server "command_to_execute"

Logs into a remote server and executes a specific command without logging into the remote shell.

Copy a File from a Remote Server to the Local Machine

scp username@remote_server:/path/to/remote/file /path/to/local/directory

Uses the scp command over ssh to securely copy a file from a remote server to a specified directory on the local machine.

Create a Secure Tunnel to Access a Service

ssh -L local_port:localhost:remote_port username@remote_server

Establishes a local port tunnel to access a service running on a remote server by forwarding traffic to the remote port.

Tip

When using the ssh command in Linux, make sure to replace <value> with the appropriate options or arguments according to your specific use case. Always ensure that you have the necessary permissions and credentials to access the remote server before attempting to establish a connection using ssh.

How do I use ssh in Linux?

To use the ssh command in bash, execute the following command:

ssh username@hostname

What are some common options for the ssh command in Linux?

To specify a port for the ssh connection, use the -p option followed by the port number:

ssh -p 2222 username@hostname

How can I copy files over an ssh connection in Linux?

To securely transfer files over an ssh connection, use the scp command. For example, to copy a local file to a remote server:

scp /path/to/local/file.txt username@hostname:/path/to/destination/

How do I force ssh to use a particular authentication key in Linux?

To specify which private key to use for authentication, use the -i option followed by the path to the private key file:

ssh -i ~/.ssh/custom_key username@hostname

How can I run a command on a remote server using ssh in Linux?

To execute a command on a remote server without logging in interactively, append the command to the ssh connection:

ssh username@hostname 'command_to_run'

How do I enable verbose mode for ssh in Linux?

To see detailed debugging information during the ssh connection process, use the -v option:

ssh -v username@hostname

How can I forward ports using ssh in Linux?

To set up port forwarding for specific ports on the local and remote machines, use the -L option followed by the port numbers:

ssh -L local_port:destination_address:destination_port username@hostname

How do I securely tunnel my web traffic through ssh in Linux?

To create a secure SSH tunnel for web traffic, use the -D option followed by a local port. Configure your browser to use a SOCKS proxy on the specified port:

ssh -D local_port username@hostname

Applications of the ssh command

• Remote login to a server
• Secure file transfer between machines
• Running commands on a remote machine
• Port forwarding
• Tunneling
• X11 forwarding