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Source repo: sdsc-summer-institute-2022 | Branch: main | Last synced: 2026-04-24 10:27:17.425 UTC

Data Management: Or how (not) to handle your data in an HPC environment

Easy access: Setting up SSH keys 🔑​

SSH, or Secure SHell, is a cryptographically secure network protocol used to administer and communicate with remote computer systems distributed over an unsecured network like the public internet. Based on a client–server architecture, the protocol supports several different methods of authentication to establish trust between client and server and uses strong encryption to protect the data they exhange. The most popular application of SSH is logging into and executing commands on a remote machine like Expanse from your personal computer.

Image Credit: OpenSSH | Wikipedia

In general, password-based authentication is the default authentication mechanism used to establish trust and open an SSH connection between a client and server. This is true on Expanse. However, SSH supports a number of different authentication mechanisms like public-key cryptography.

Today, many systems also require two-factor authentication.

Step 1 - Generate an SSH key pair (with a passphrase) on your personal computer​

ssh-keygen -t rsa -b 4096 -a 128 -f ~/.ssh/sdsc-si22
Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/your_local_username/.ssh/sdsc-si22
Your public key has been saved in /home/your_local_username/.ssh/sdsc-si22.pub
The key fingerprint is:
SHA256:doNjZ99n+cFG7DBeMtBIdDroNkQF7C70Rd9yxysgCH4 myour_local_username@your_local_hostname
The key's randomart image is:
+---[RSA 4096]----+
|        .o++ .   |
|     .  ..o.=    |
|    . . oo.=.... |
|     . Eo+ ooo.oo|
|      o S+B .=o+o|
|       +.B.o.oX..|
|        .   ..o*o|
|              .oo|
|                .|
+----[SHA256]-----+
Generating public/private rsa key pair.
/home/your_local_username/.ssh/sdsc-si22 already exists.
Overwrite (y/n)? n
$ ls ~/.ssh
config  id_rsa  id_rsa.pub  known_hosts  sdsc-si22  sdsc-si22.pub

Step 2 - Copy your public SSH key to Expanse​

ssh-copy-id -i ~/.ssh/sdsc-si22 xdtr@login.expanse.sdsc.edu
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/your_local_username/.ssh/sdsc-si22.pub"
The authenticity of host 'login.expanse.sdsc.edu (198.202.100.14)' can't be established.
ED25519 key fingerprint is SHA256:L2aPmUWNAwHOBbYNYX/E0P/hPIoyJzq9Wt6g/PFDjJ8.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
Password:
Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'xdtr@login.expanse.sdsc.edu'"
and check to make sure that only the key(s) you wanted were added.
Verification code:

Step 3 - Login to Expanse using your SSH keys​

ssh -i ~/.ssh/sdsc-si22 xdtr@login.expanse.sdsc.edu
Welcome to Bright release         9.0

                                                         Based on Rocky Linux 8
                                                                    ID: #000002

--------------------------------------------------------------------------------

                                 WELCOME TO
                  _______  __ ____  ___    _   _______ ______
                 / ____/ |/ // __ \/   |  / | / / ___// ____/
                / __/  |   // /_/ / /| | /  |/ /\__ \/ __/
               / /___ /   |/ ____/ ___ |/ /|  /___/ / /___
              /_____//_/|_/_/   /_/  |_/_/ |_//____/_____/

--------------------------------------------------------------------------------

Use the following commands to adjust your environment:

'module avail'            - show available modules
'module add `module`'     - adds a module to your environment for this session
'module initadd `module`' - configure module to be loaded at every login

-------------------------------------------------------------------------------
Last login: Mon Jul 25 15:05:09 2022 from 208.58.214.56
[xdtr@login02 ~]$
[xdtr@login02 ~]$ exit
logout
Connection to login.expanse.sdsc.edu closed.
$
$ ssh-add -l
4096 SHA256:doNjZ99n+cFG7DBeMtBIdDroNkQF7C70Rd9yxysgCH4 your_local_username@your_local_hostname (RSA)
$ cat ~/.ssh/sdsc-si22.pub
ssh-rsa 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 your_local_username@your_local_hostname
[xdtr@login01 ~]$ cat ~/.ssh/authorized_keys 
ssh-rsa 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 your_local_username@your_local_hostname
[xdtr@login01 ~]$ ssh-keygen -l -f ~/.ssh/authorized_keys 
4096 SHA256:doNjZ99n+cFG7DBeMtBIdDroNkQF7C70Rd9yxysgCH4 your_local_username@your_local_hostname (RSA)

Step 4 - Simplify your login by creating a local SSH configuration file​

$ touch ~/.ssh/config
$ chmod u+rw ~/.ssh/config
$ chmod go-rwx ~/.ssh/config
$ ls -lh ~/.ssh/config 
-rw------- 1 your_local_username your_local_groupname 398 Jun 27 05:33 /home/your_local_username/.ssh/config
Host expanse
Hostname login.expanse.sdsc.edu
User xdtr
IdentityFile ~/.ssh/sdsc-si22
$ ssh expanse

Next - CIFAR through the tubes: Downloading data from the internet