SSH Proxy Jump: Simplifying Secure SSH Connections

Secure Shell (SSH) is a widely-used protocol for securely connecting to remote servers over an untrusted network, such as the internet. SSH ensures the confidentiality and integrity of data exchanged between the client and server. However, managing SSH connections to servers with complex network configurations can be challenging. This is where SSH Proxy Jump, also known as SSH Jump Host or SSH Bastion Host, comes in handy.

SSH Proxy Jump allows you to connect to a target server through an intermediate server, known as a jump host or bastion host. This intermediate server acts as a gateway, helping you traverse complex network topologies while maintaining security. In this article, we’ll explore how to use SSH Proxy Jump both via the command line and through SSH configuration files.

Via Command Line

You can establish an SSH connection using Proxy Jump directly from the command line. Here’s the basic syntax:

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ssh -J jump_host:port target_host -t command

In this command:

• jump_host:port is the address and port of the jump host.
• target_host is the address of the final destination.
• command is an optional command to run on the target host.

For example, to open a Vim session on the example-storage-server via the origin.example.net jump host on port 667, you can use the following command:

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ssh -J origin.example.net:667 example-storage-server -t vim

Via SSH Configuration File

Using SSH Proxy Jump via the command line can be convenient for one-off connections. However, if you frequently connect to servers through a jump host, it’s more practical to configure SSH to do this automatically. You can achieve this by editing the SSH configuration file, typically located at ~/.ssh/config.

Here’s an example of how to set up SSH Proxy Jump in your configuration file:

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Host jump_host
  HostName origin.example.net
  Port 667
  User root

Host target_host
  HostName example-storage-server.local
  User root
  ProxyJump jump_host

In this example:

• jump_host is an alias for the jump host with its hostname, port, and user specified.
• target_host is an alias for the final destination server.
• ProxyJump jump_host tells SSH to use jump_host as the intermediary to connect to target_host.

With this configuration in place, you can connect to the example-storage-server with a simple command:

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ssh target_host

SSH will automatically use the jump_host as the proxy to reach the example-storage-server.

Conclusion

SSH Proxy Jump is a powerful feature that simplifies secure SSH connections, especially in complex network environments. Whether you prefer using the command line or SSH configuration files, Proxy Jump can make your remote server management more efficient and secure. By following the examples provided in this article, you can easily set up SSH Proxy Jump to streamline your SSH connections.