ssh Command

Purpose

Establishes encrypted remote shell sessions by using the SSH protocol.

Syntax

ssh [ -4 ] [ -6 ] [ -F file ] [ -h ] [ -i file ] [ -o option=value ][ -p port ] [ -q ] [ -v ] [user@]hostname [ command ]

Description

The ssh command establishes encrypted remote shell sessions by using the SSH protocol. In PowerVC virtual appliance, only outbound client connections to pre-approved hosts and ports are allowed for security. Server mode, key generation, or privileged operations are not allowed.

Flags

Table 1. Flags
Items	Description
-4	Uses only the IPv4 addresses when SSH connects to a remote host.
-6	Uses only the IPv4 addresses when SSH connects to a remote host.
-h or --help	Displays help about the ssh command.
-F `file`	Specifies an alternative configuration file. The ssh command looks for configuration settings in the ~/.ssh/config file by default. If the -F flag is used with the ssh command, the ssh command looks for the configuration settings in the specified file.
-i `file`	Uses a specific private key (identity file) for authentication to login to a remote server.
-o `option=value`	Specifies configuration settings in the format `option=value`. This option is useful for advanced SSH configuration. For example, `StrictHostKeyChecking=no`, `ConnectTimeout=10`.
-p `port`	Specifies a port to connect to a remote server. By default, SSH uses port `22`. Only nonprivileged ports (`>1024`) are allowed unless a port is pre-approved.
-q	Suppress warnings and diagnostic messages.
-v	Enables verbose output. This option displays the debugging messages, which is useful to debug connection issues.

Positional arguments

Table 2. Positional arguments
Item	Description
`user`@`hostname`	Specifies the remote username and the hostname in `user@hostname` format (For example alice@xxx.xxx.x.xxx). If the username is omitted, the current local username is used. The `hostname` argument can be a domain name or an IP address of the remote system. This argument is a required field.
`command`	The `command` argument specifies one or more commands that must run on the remote server after the secure connection is established. This argument is optional.

Examples

To connect to a remote host and start an interactive shell, enter the following command:
```
ssh user@example.com
```
To connect to a remote host by using specific port and key, enter the following command:
```
ssh -p 2222 -i ~/.ssh/id_ed25519 user@backup.server
```
To connect to a remote server and run the df -h command remotely, enter the following command:
```
ssh user@web01 'df -h /'
```
To establish a quiet connection with timeout, enter the following command:
```
ssh -q -o ConnectTimeout=5 user@monitor.local uptime
```
To use only the IPv4 address and disable host key checking for automation, enter the following command:
```
ssh -4 -o StrictHostKeyChecking=no user@monitor.local
```