SSH Connection Using a Terminal

Appropriate usage of login nodes

The login nodes are the gateways we use to perform light interactive work like editing code, submitting and checking the status of jobs, etc. Executing CPU-heavy scripts on these nodes can cause slowdown for everyone. It is important to make sure that CPU-heavy work is done in either an interactive session on a compute node or as a batch job submission.

Resource-intensive processes running on the login nodes may be killed at any time.

The CRCD team reserves the right to revoke cluster access of any user who repeatedly causes slowdowns on the login nodes with processes that can otherwise be run on the compute nodes.

SSH (Secure Shell) is a network protocol that allows for secure access to a computer over an unsecured network. This is the protocol for connecting to the CRCD login nodes.

As with any of the other methods for connecting to CRCD resources, you should start by ensuring you have a proper connection to the GlobalProtect VPN (see Step 1). With this connection established, you can proceed with the steps below.

Clients running MacOS can use the built-in Terminal app (in Applications/Utilities) or iTerm2. Clients running Windows can use MobaXterm or PuTTY to access a terminal emulator.

To render graphics from the remote session, you will also need an X server on your client. For MacOS, you will need to install XQuartz. MobaXterm comes bundled with an X server.

Connection settings

Setting	Value
Remote Host	h2p.crc.pitt.edu or htc.crc.pitt.edu
Port	22
Username	Your Pitt username, all lowercase
Authentication	Pitt password, or an SSH key — see Passwordless SSH

The syntax to connect to the CRCD login node from your terminal command line is

ssh -X <username>@h2p.crc.pitt.edu

where <username> is your Pitt username in lowercase and the answer to the prompt is the corresponding password. Use htc.crc.pitt.edu instead to reach the HTC cluster. The -X option enables X forwarding for applications that generate a GUI such as xclock.

Skip the password next time

You can log in with an SSH key instead of typing your Pitt password on every connection. See Passwordless SSH to set it up.

If this is the first time that your client machine is logging into h2p.crc.pitt.edu, you will see a warning that "The authenticity of the host ... can't be established" and if you wish to continue connecting. Answer: yes.

If your connection is successful, your client session will look like the screenshot below.

Successfully logged in to login node

MacOSWindows

Definitions

• terminal emulator -- a software program that provides a text-based interface to the system, allowing users to type commands into a shell prompt to run programs and to manage files without a graphical user interface (GUI)
• Linux shell -- a text-based user-interface that interprets user commands and scripts. CRCD supports bash and csh, with bash being the default
• Linux commandline -- this is the shell prompt line where your cursor is highlighted and where you input commands to the remote host

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