SSH config and login to UI via Jumphost for users on Windows

There are two options to login to clusters from Windows

1. (preferred) Either by using MobaXterm client software which requires installation
2. alternative option is to use built-in OpenSSH software that comes pre-installed with newer versions of Windows (10+)

1. MobaXterm option

The instructions below assume:

• you've already downloaded MobaXterm to generate a pair of SSH keys (using the instructions for requesting accounts)
• and verified your MobaXterm version is 12.3 or newer (older ones have a known bug and won't work.)
• and will now use MobaXterm to login to the cluster
• and that you received a notification with your account name and that your account has been activated
• and that you are on the machine from which you want to connect to the cluster.

If you prefer another terminal application consult the corresponding manual.

1.1 Launch MobaXterm and create a new session

• Launch MobaXterm version 12.3 or newer and click the Session button from the top left of the window.
• A Session settings window will popup.

1.2 Configure a new session

• Session type
  • 1: Select SSH.
• Basic SSH settings tab
  • 2: Remote host field: Use the name of the User Interface (UI) hyperchicken .
  • 3: Specify username field: Use your account name as you received it by email from the helpdesk.
• Advanced SSH settings tab:
  • 4: Use private key field: Select the private key file you generated previously.

• Network settings tab
  • Click on the large SSH gateway (jump host) button.

• SSH jump hosts popup window

  • 5: Gateway host field: Use 45.88.81.146 for the Jumphost address.
  • Optional: Port field: The default port for SSH is 22 and this is usually fine. However if you encounter a network where port 22 is blocked, you can try port 443. (Normally used for HTTPS, but our Jumposts can use it for SSH too.)
  • 6: Username field: Use your account name as you received it by email from the helpdesk (same as for 3).
  • 7: Select Use SSH key and
  • 8: Click the small button to select the private key file you generated previously (same as for 4). Important: the path to the selected private key will be shown. Depending on how you browsed to the private key file, the path may
    • Either start with a drive letter, colon and single backslash. E.g. H:\path\to\private_key.ppk This is fine and should work.
    • Or start with two backslashes. E.g. \\path\to\private_key.ppk This won't work and MobaXterm will fail silently: no login, no error, no nothing. Use a different route in the GUI to browse to your private key file such that the path starts with a drive letter, colon and single backslash.
  • 9: Click OK

• Back in the network settings tab

  • 10: Click Ok

1.3 Password (popup)

• MobaXterm should now produce a popup window where you can enter the password to decrypt the private key.
  • Note this is the password you chose yourself when you created the key pair.
  • You are the only one that ever knew this password; we have no copy/backup whatsoever on the server side. If you forgot the password, the private key is useless and you will have to start over by creating a new key pair.

1.4 Password again (prompt)

MobaXterm should now start a session and login to the Jumphost resulting in

• a session tab (left part of the window with white background) and
• a terminal where you can type commands (right part of the screen with black background).

In the terminal tab MobaXterm will try to login from the Jumphost to the User Interface (UI) with the same private key file. This may require retyping the password to decrypt the private key a second time, this time in the terminal tab.

1.5 Session established

You have now logged in to the UI hyperchicken.

The left part of the window with white background switched to a file browser, while the right part remains a terminal where you can type commands.

2. Using Windows OpenSSH

2.1 Semi-automatic configuration with .bat script

You can download the executable script from here logins-windows.bat and use it to configure ssh connection for the hyperchicken.

If you try to download the script with Microsoft Edge (default browser), then

• Microsoft Edge: you will twice need to confirm that the file is safe and that your really want to store it (see Download icon, where you must select Keep, then Show more > Keep anyway)
• other web browsers: the download itself is easier, but when executing you get Windows protected warning, and you must click on More info text (small text at top left part of the window), then select Run anyway.
• alternatively, you can simply click on the link, then select all the text, copy and paste into a filename named logins-windows.bat (the .bat ending is mandatory in order the file to become executable)

Once you have the file, run it and the rest of the configuration will be (for except two prompts) done almost automatically.

The configuration files will be stored inside the C:\Users\[Username]\.ssh\ folder.

2.1 Manual configuration with

(to be updated)

The ssh configuration files can be created inside the C:\Users\[Username]\.ssh\ folder. In order to manually create them, you can simply follow the instructions for linux ssh configuration.

There are many differences between the linux and windows OpenSSH configuration. One of the biggest is the difference beween linux / and windows \ as directory path separator. But there are many more. Users that do not understand those differences, should use the MobaXterm or semi-automatic .bat script options above.

2.3 Connecting to the system

In order to connect to the hyperchicken

• first open Start menu, search and execute the cmd or Command Prompt program
• login to hyperchicken by using a command ssh umcg-username@portal+hyperchicken

2.4 Port forwarding to the compute nodes

Users can connect ports on own computer to the ports on the compute nodes behind the jumphosts - by using port forwarding (binding). In order to do this, user must open another cmd environment and establish a connection with numbers of the ports to be forwarded

ssh -J portal hyperchicken -L XXXXX:NODE:XXXXX

where

• -J portal specify which jumphost machine is going to be used in order oppening the connection to ...
• hyperchicken is the name of the machine that user will connect and have the command line started
• -L XXXXX:NODE:XXXXX defines the ports and machines to connect
  • XXXXX can be set to any port in the range (1024 < XXXXX <= 65535) as long it is free on both (your local and remote) servers,
  • note that this example binds the same XXXXX ports on both local as well as remote server - but this is not mandatory, they can be different,
  • NODE is the name of the remote server behind a jumphsot to which the ports should be forwarded.

More information about ssh options can be find on the ssh man pages.

2.5 Converting Putty .ppk key into OpenSSH format

Public/private keypairs created with Putty program are by default stored in the Putty private key (ppk) format. The private keys files also have .ppk ending. The file format is not compatible with generic OpenSSH format (which most of ssh client programs use) and the key must either be recreated (and public part sent to helpdesk) or existing private key must be converted into more usable OpenSSH format.

In order to convert an existing keypair from Putty into OpenSSH format

• puttygen.exe can be downloaded from Putty webpage
• run program > click Load > select ppk (private key)
• to store the PUBLIC part of the keypair into OpenSSH format, select all the text inside Key: Public key for pasting into OpenSSH authorized_keys file and save it in a file with .pub ending (like username.pub)
• to store PRIVATE part of the keypair (while still loaded the same ppk key)
• click Conversions
• Export OpenSSH key > confirm
• store same filename but without any ending (simply a username for a filename should be descriptive enough)

---

Back to operating system independent instructions for logins