Connecting to ARC clusters

Connecting to ARC

Access to ARC systems is via Secure Shell Protocol (SSH).

Fingerprints for the login node host keys can be found at the bottom of this page.

Linux and Mac (and other Unix/Unix-like systems)

Linux and Mac users should use ssh from a terminal to connect to the ARC systems.

To connect to the ARC cluster:

ssh -X

To connect to the HTC cluster:

ssh -X

Access to ARC is available only from within the University of Oxford network. If you are not on the University network, you should use the University VPN service to connect. If you are unable to use the VPN service, you may be able to register your static IP with the ARC team ( to enable access.

If you are connecting from outside the University network (or from the VPN service) you will need to connect via - ensure you specify your ARC username in the ssh command, as shown below:

ssh -X

You can then SSH to arc-login or htc-login as required.

Note: The above examples include the -X option which allows the tunnelling of X11 graphics from the cluster to your local machine. This is optional.

However, if you do require graphics, an X11 server needs to be running on your local machine. For Linux this is typically part of the installation - however on a Mac you may need to install an X11 server such as Xquartz.


SSH is available as a command in PowerShell from Windows 10. Users of Windows 10 or newer should be able to connect to ARC from PowerShell with the commands given above. However, users of older Windows version, or those requiring X11 forwarding, will need to download and install an application that allows them to connect - a great example is MobaXterm.

Download MobaXterm here.


How do I copy data to/from ARC?

MacOS/Linux users (and other Unix like operating systems) can use rsync, sftp, or scp. Please note: $HOME and $DATA are shared between the ARC and HTC systems, so the instructions below will work for both systems.

Copying to the ARC systems

1) Make sure you know the path to the destination directory. Login to arc and create a directory in $HOME or $DATA , change to that directory, run the command pwd and this will show you the path to the destination directory. 

For example if you have created a directory myscripts in $HOME , pwd will show output like:



2) On your Mac or Linux PC open a terminal use the command 'cd directoryname'  to get to the source directory where the file(s) you want to copy are located. The command pwd will show the full path to this directory, take note of this path. For example if you have a directory scripts the path might be something like :



3) Still on your MAC or Linux PC to copy files use an scp command with the format:

scp path/filename

Continuing with the above example -  to copy all the files in /local/scripts this would be:

scp /local/scripts/*

To copy an entire directory hierarchy use the recurse option, -r

For example:

scp -r /local/scripts/*

In both the above cases, you will be prompted to authenticate with your ARC password.

Copying from the ARC systems
The reverse should be used for copying from arc. Using the methods above, take note of the source (ARC) and destination (local PC) paths. In this example these will be:
ARC directory:  /home/ouit0578/mydata
Local PC directory: /local/datafromarc
From your Mac or Linuc PC :
scp* /local/datafromarc/

Again a recursive copy can be made using the -r option.

scp -r* /local/datafromarc/

In both the above cases, you will be prompted to authenticate with your ARC password.

Copying to/from Windows clients

Windows users can use tools such as MobaXterm or WinSCP to copy files. Make sure you use as the hostname you connect to and use the discovery method in step 1) above to work out the remote ARC path for the transfer.


How do I change my password?

Passwords can be changed by running the "passwd" command from a terminal:

user@arc-login~$ passwd Enter login(LDAP) password:

Enter new passwd:

Re-enter new passwd:

If you need to change other things in your account (e.g. email address), this is possible - please ask the ARC team by emailing

Host key fingerprints for ARC login nodes

server name hash algorithm signature type fingerprint

arc-login MD5 ED25519 3e:d7:e1:20:76:91:af:5c:54:82:9d:15:c6:42:52:85  
RSA da:b7:c2:d3:66:f7:0b:35:e5:96:7e:b5:ae:8e:ff:de
ECDSA f2:d7:01:cb:3c:14:ca:1f:c8:6a:34:a9:8c:f2:74:e4
SHA256 RSA 47OUV3Jm8crB/j9NkSBa8sjBT6uJ7TVvJ+Hi1XUmyAI
ED25519 GA6PFIk/IYl5ERzqElm3Jts10kg+VwMWKbSIU9CDi6g
ECDSA qRv0Jhq96SQH+g4lHrOtJm3sxtnn0p48h20hWWy1zog

htc-login MD5 RSA b0:6e:1e:1f:d7:be:5f:a4:6f:70:1c:d7:9e:1c:b1:a1
ECDSA 68:5e:c4:3d:8d:98:bc:cd:15:12:67:1e:ba:2e:6f:3c
ED25519 fe:46:78:54:87:d6:d8:ae:d2:31:df:61:69:e3:50:d4
SHA256 ECDSA +4MBr+UWPBcQl+uomfWQRYaX3H5rRci1ZTNZyaRpjBg
ED25519 2Exs0VBQhgVq5ALTA+kYiNlTAuzGpdz0+NaIFDYzWQw
RSA olV+xMGjg4RVxO/PKcPFVrbtfunsAMYW3Qqb5pmxDMQ

gateway MD5 RSA 87:84:69:ff:10:4a:01:fa:64:66:28:31:66:1b:3e:7e
ED25519 75:a3:c4:d2:38:12:0a:d0:00:d6:d2:ba:15:31:e4:67
ECDSA 9e:98:ec:c3:e3:fd:ef:de:99:03:5a:7e:50:d0:17:b5
ED25519 9Ie6SKcTU1uvfPSYqvNZ4hHadibLbsb7IZ4yGQn8UJc
ECDSA 9Yxtz0/6BXykwap0EgRWKxfQ5sp0Rm9qxQGVE+eOk2Y

arcus-htc MD5 ECDSA 9d:ca:b7:4f:a8:16:8e:f2:ea:16:fa:1d:9f:a2:b4:f2
ED25519 c6:e0:95:84:3c:4b:31:ba:07:8a:7f:82:5d:de:37:d9
RSA d1:83:21:b1:f2:bd:8f:e7:5d:cd:74:d1:73:b9:70:7a
SHA256 ECDSA VFp2VnS9qxEZ7T2Z16c+2NDq9JbKU2SNA23WpMdbYpU
ED25519 WvhqbkPMQp9oqlCZxpl/kzI+gRpf9k1zDuvyxAfzecg
RSA acUTOlYintwdjtrinOoecuw8rfz+CRWS0PDxvn1/Ptw

arcus-b MD5 RSA 1b:77:95:d5:33:74:b5:2e:94:32:9b:f1:75:ff:c1:1f

How do I access the ARC systems from outisde the University network?

You need to use Oxford Univeristy VPN 

If that is not possible please email