SSH Connections

This tutorial introduces SSH (Secure Shell) as a tool to connect to other Linux machines over a network. It is the most common way to connect to and interact with a cluster. A SSH server is expected to be running on the remote computer, while clients for Linux, Mac OS and Windows are available to establish the connection. This tutorials will teach you how to establish a connection and create a key for public key authentication, which is considered to be the most secure option.

Video

( Slides as pdf)

Quiz

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What is the correct syntax to open a ssh connection?

	ssh [options] <username>@<hostname>
	ssh <username>:<hostname> [options]
	ssh [options] <username> <hostname>

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Where is your ssh config stored on Linux?

	~/sshconfig
	~/.config/ssh
	~/.ssh

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What tools help you with creating and installing a ssh key-pair? (on Linux)

	ssh-keygen to create the key files and ssh-copy-id to copy it to the remote machine
	ssh --keygen to create the key files and ssh --copy-id to copy it to the remote machine

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Does it cause a security problem to share an SSH public key with your friends?

	Yes
	No

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Which authentication for SSH login is more secure?

	password authentication
	public key authentication

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When generating the SSH public/private key pair, is it secure to use empty passphrase?

	Yes
	No

Info:

Verify the fingerprint of remote host, before the first login. User the SSH public key authentication for login. Never use an empty passphrase for the SSH keys. Use strong passphrase to generate the SSH keys. Keep your private SSH key as top secret. Create, configure and use different SSH keys for different remote hosts. If no X11 application is required, disable X11 forwarding. Otherwise, only enable the untrusted X11 forwarding.

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