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Accessing Clusters

In order to access your HPC account, you may need to generate an SSH key pair for authorization. You generate a pair of keys: a public key and a private key. The private key is kept securely on your computer or device. The public key is submitted to HPCCF to grant you access to a cluster.

How do I generate an SSH key pair?

Windows Operating System

We recommend MobaXterm as the most straightforward SSH client. You can download the free Home Edition (Installer Edition) from MobaXterm. Please download the Installer Edition. The Portable Edition deletes the contents of your home directory by default when it exits, which will remove your freshly generate SSH key. Once you install the stable version of MobaXterm, open its terminal and enter this command:

ssh-keygen

This command will create a private key and a public key. Do not share your private key; we recommend giving it a passphrase for security. To view the .ssh directory and to read the public key, enter these commands:

ls -al ~/.ssh
cat ~/.ssh/*.pub

macOS and Linux:

Use a terminal to create an SSH key pair using the command:

ssh-keygen

To view the .ssh directory and to read the public key, enter these commands:

ls -al ~/.ssh
cat ~/.ssh/*.pub

X11 Forwarding

Some software has a Graphical User Interface (GUI), and so requires X11 to be enabled. X11 forwarding allows an application on a remote server (in this case, Franklin) to render its GUI on a local system (your computer). How this is enabled depends on the operating system the computer you are using to access Franklin is running.

Linux

If you are SSHing from a Linux distribution, you likely already have an X11 server running locally, and can support forwarding natively. If you are on campus, you can use the -Y flag to enable it, like:

$ ssh -Y [USER]@[CLUSTER].hpc.ucdavis.edu

If you are off campus on a slower internet connection, you may get better performance by enabling compression with:

$ ssh -Y -C [USER]@[CLUSTER].hpc.ucdavis.edu

If you have multiple SSH key pairs, and you want to use a specific private key to connect to the clusters, use the otpion -i to specify path to the private key with SSH:

$ ssh -i ~/.ssh/id_hpc [USER]@[CLUSTER].hpc.ucdavis.edu

macOS

macOS does not come with an X11 implementation out of the box. You will first need to install the free, open-source XQuartz package, after which you can use the same ssh flags as described in the Linux instructions.

Windows

If you are using our recommend windows SSH client (MobaXterm) X11 forwarding should be enabled by default. You can confirm this by checking that the X11-Forwarding box is ticked under your Franklin session settings. For off-campus access, you may want to tick the Compression box as well.

SSH key fingerprint issues

Are you sure you want to continue connecting (yes/no/[fingerprint])?

SSH key fingerprint prompts like below happen the first time you connect to a server from your system(s). You should compare the fingerprint printed with the fingerprints listed below. If they match, you can safely enter yes. If you cannot find a match, you should open a ticket.

Are you sure you want to continue connecting (yes/no/[fingerprint])? 
All keys already loaded
The authenticity of host 'farm.hpc.ucdavis.edu (128.120.146.1)' can't be established.
ED25519 key fingerprint is SHA256:qiPI72KfRjrAeEdww3RVkrM1Bi7GE6sEoS4JRnKzC1I.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED

SSH key fingerprint errors like below are normally caused when a host is reinstalled and the newly generated SSH host key differs from the last time you SSH'd to the server. You should compare the SHA256:LongRandomStringHere part against the host fingerprints listed below. If they match, you can safely follow the instructions ssh-keygen -f .... If they differ, you should open a ticket.

WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED 
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:LongRandomStringHere.
Please contact your system administrator.
Add correct host key in /home/YourLocalLoginID/.ssh/known_hosts to get rid of this
message.
Offending ECDSA key in /home/YourLocalLoginID/.ssh/known_hosts:32
remove with:
ssh-keygen -f "/home/YourLocalLoginID/.ssh/known_hosts" -R "Server.You.SSH'd.To"
ECDSA host key for Server.You.SSH'd.To has changed and you have requested strict checking.

SSH key fingerprints for major clusters

farm.hpc.ucdavis.edu

  • RSA: SHA256:aPUfAVTLNju9Omu8yIr5NYXAmZVKjsCLvewfAt8BLo8
  • ECDSA: SHA256:XsfxXdolugXtm5/nWuEX0UB3mkllshTHTx+yHXQTrE0
  • ED25519: SHA256:qiPI72KfRjrAeEdww3RVkrM1Bi7GE6sEoS4JRnKzC1I

franklin.hpc.ucdavis.edu

  • RSA: SHA256:mXcTBeL5xCfcMmLEEYu4ppIFM82X7vc5AGJjvEyoJxg
  • ECDSA: SHA256:e2mldm10c9VYZceHB62MQpMtgL2sZ10W0H3U/tsUHws
  • ED25519: SHA256:RFw1dHndgpDgv0p8VyHW1QQt3JVq7CEzlQ9fKnfAAoY

hive.hpc.ucdavis.edu

  • ECDSA: SHA256:AmJ+z2miIMXlSAcm7k8YwKlIWk5+VqxyT0R4q3fvpcA
  • ED25519: SHA256:b5nv86Ciaqg1yrUVai6bZ0Hk4IpzAFLWtIPDBdacbQM

hpc2.engr.ucdavis.edu

  • RSA: SHA256:ZC23UiJLib0sozDEClkmD5q+TgeZf/mol6xzIQY30xE
  • ECDSA: SHA256:ymN3g0Ow4BM2Rd/zE3THZg7nv+mOs75ENCe5GcvWQoM
  • ED25519: SHA256:Svzxx62P/NxrsISeyPZ06nW+YkDYsE1xQc1wD/61tFI

peloton.hpc.ucdavis.edu

  • RSA: SHA256:eVU5TeDV+ezOkVHVA9d/L6CrcPihU1POpw8uPh4iXuQ
  • ECDSA: SHA256:QFH7ONkN7edAoYEu0GfTz7prqvi1YYu4bep7hxNrswU
  • ED25519: SHA256:ydOUR2t/MX3jbd3JIHDXMJyLjdhRV4OBLr9iJfQB8lw