SSH

An important part of system administration is a secure connection to it. With SSH we can achieve this easily. At the same time, there is a lot more to this protocol and set of commands. In this section all articles and configuration are collected.

Change SSH server port number

Learn how to make changes to your SSH configuration to have it running on a different port than its default 22/TCP.

Configure a SSH welcome message or banner

Learn how to configure a welcome messages for users before or after logging in via SSH.

SSH escape sequences

Learn about the escape sequences that can be used with OpenSSH to initiate special commands.

Using SSH keys instead of passwords

Linux systems are usually managed remotely with SSH, often still using passwords. Time to switch over to SSH keys and here is how to do that.

Frequently Asked Questions

How to add a SSH key to the SSH agent?

ssh-add ~/.ssh/id_ed25519

» Full answer and more examples


What is SSH agent forwarding?

The agent forwarding feature in SSH allows using your local SSH agent to be reached through an existing SSH connection. This way you don't have to store copies of your private keys on intermediate systems to use them for authentication.

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How to start the SSH agent?

eval $(ssh-agent)

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What is the purpose of the SSH agent?

The SSH agent is a helper utility to temporarily store private keys when using public key authentication. It acts as an authentication agent for clients such as the ssh command.

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How to disable the usage of the SSH agent?

ssh -o IdentityAgent=none user@hostname

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How to disable the SSH check of host authenticity and the key fingerprint?

ssh -o StrictHostKeyChecking=no user@hostname

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How to terminate a SSH connection that does not respond to CTRL+C?

Press tilde (~) followed by a dot (.)

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How to remove the passphrase from a SSH key?

ssh-keygen -p -f /path/to-key-file

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How to see the available SSH keys in the OpenSSH authentication agent?

ssh-add -l

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See all frequently asked questions for SSH