Flexible Connections
note
As a rule, we prohibit users running processes on the login node. A ProxyJump is a useful solution that can help you link external software to the server for real time code development.
Spending some time on SSH#
All of your connections to Hyak are going to go through SSH, so it's worth customizing your configurations to make this process as easy as possible. We're going to modify our main SSH configuration, and create a sub-configuration that we can use for automation later in this guide.
This will be fairly quick, but please note we will be doing some additional work on these files in the next section, so don't skip past this.
Your configuration on the cluster#
There's really only one thing that needs to be set up on the cluster: your intracluster keys. Like many other parts of this guide, we already have instructions on this, but since we're keeping this guide self-contained, we'll go through it again here:
If you haven't already done so, log in to the cluster & generate an intracluster SSH key:
After that, add the key to your authorized_keys file and ensure the permissions are correct:
A set of customized, local configurations#
important
This entire next section is done on your local computer—your personal MacOS/Linux or Windows machine—not on the cluster.
Your primary SSH config#
First up is our main SSH configuration file, located at ~/.ssh/config. The contents of your SSH configuration file will depend on the operating system of your local machine (Mac/Linux or Windows).
Mac/Linux Users#
You can use the following template, making sure to change out UWNetID for your UW Net ID that you use to log in:
Whether you're creating this file for the first time, or modifying an existing config, make sure the file has the correct permissions:
Once this is in place, we can do the following to log in to klone:
Here's a quick rundown of the options we're setting:
ServerAliveInterval 30: every 30 seconds, send a packet to the server (the login node) to keep the connection open.ServerAliveCountMax 1200: don't close the connection unless we've sent 1200 server-alive messages without a response from the login node.ControlMaster auto: enable SSH multiplexing, i.e. connection sharing. This means once we've established the first connection, we won't have to reauthenticate for subsequent connections: the new connection will just use the already open socket. This feature is no supported for Windows Users.ControlPersist 3600: this keeps the control socket open for an hour after the initial connection has been closed.ControlPath ~/.ssh/%r@klone-login:%p: this is the path where the socket, appearing as a file, will actually be located. The%ris an abbreviation for the remote username, i.e. your UW Net ID, and%pis an abbreviation for the port (normally 22 for SSH).
Finally, the last line will include the next file we're going to make: A secondary config for the node.
Windows Users#
You can use the following template, making sure to change out UWNetID for your UW Net ID that you use to log in:
A secondary config for the node#
These instructions are the same for Windows and Mac/Linux users.
Here we're defining klone-node as a compute node (n3000, until we know what the node will be), and
using ProxyJump to connect to that node through the login node.
This file will also need the correct permissions. Windows should not require a permissions check. Mac/Linux update permissions with:
Because you will be effectively connecting directly from your local computer to the node, you will need to append the SSH public key from your local system to the .ssh/authorized_keys file under your cluster home directory on klone. Or you can do the same by copying your local ssh key onto klone. While we cannot use our key as a authentication factor between our local machine and klone, we can use it when ssh'ing between klone nodes.
Windows Users#
If your private key permissions are too open, ssh won't let you connect to klone. To solve this, change the permissions on your private key file. Apply this solution.
Testing your connection#
note
You will test the connection in the next section of the Hyak 101 tutorial. If you wish to test your connection now, follow these steps.
First, test your new ssh shortcut to get onto the login node.
Then, request an interactive job in the ckpt partition with 1 CPU (unless otherwise specified with --ntasks, a job will have 1 task) and 16GB of memory:
The Hostname will appear when your node is allocated, and follow your UWNetID For example:
The next section of the tutorial will introduce a script that when run on locally will replace the Hostname line of your ~/.ssh/klone-node-config file. For now, manually replace the Hostname line with your job node.
Test your shortcut to connect directly to the node from your local computer: