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ssh

The ssh command is a client connection tool in the openssh suite, which can be used to securely remote login to a server using the ssh encryption protocol.

Syntax​

ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]
           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]
           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]
           [-i identity_file] [-J [user@]host[:port]] [-L address]
           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]
           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]
           [-w local_tun[:remote_tun]] destination [command]
  • destination: Specifies the remote ssh server to connect to.
  • command: Specifies the command to execute on the remote ssh server.

Option Explanation​

  • -4: Force use of IPv4 addresses.
  • -6: Force use of IPv6 addresses.
  • -A: Enable authentication agent connection forwarding.
  • -a: Disable authentication agent connection forwarding.
  • -B: Bind to bind_interface address before attempting to connect to the target host. Useful on systems with multiple addresses.
  • -b: Use local specified address as the source IP address for corresponding connection.
  • -C: Request compression of all data.
  • -F: Specify the configuration file for SSH commands.
  • -f: Run SSH command in the background.
  • -g: Allow remote hosts to connect to local forwarded ports.
  • -i: Specify an identity (private key) file.
  • -l: Specify the login username to connect to the remote server.
  • -N: Do not execute a remote command.
  • -o: Specify configuration options.
  • -p: Specify the port on the remote server.
  • -q: Quiet mode.
  • -X: Enable X11 forwarding.
  • -x: Disable X11 forwarding.
  • -y: Enable trusted X11 forwarding.

Common Commands​

# ssh username@remote_server_address
ssh sunrise@192.168.1.10
# Specify port
ssh -p 2211 sunrise@192.168.1.10

# SSH family
ssh -p 22 user@ip  # Default username is the current username, default port is 22
ssh-keygen # Generate ssh public and private keys for the current user
ssh-keygen -f keyfile -i -m key_format -e -m key_format # key_format: RFC4716/SSH2(default) PKCS8 PEM
ssh-copy-id user@ip:port # Copy the public key of the current user to the ~/.ssh/authorized_keys file on the server that needs SSH, enabling passwordless login

Connect to remote server

ssh username@remote_host

Connect to remote server and specify port

ssh -p port username@remote_host

Connect to remote server using a key file

ssh -i path/to/private_key username@remote_host

Execute a remote command locally

ssh username@remote_host "command"

Forward a local port to a remote server

ssh -L local_port:remote_host:remote_port username@remote_host

Forward a remote port to the local machine

ssh -R remote_port:local_host:local_port username@remote_host