It is also possible to connect to the kraken server from the Internet outside the UT network. Compared to logging in from the internal network, there are the following differences:

• you log in to the server zuul.it.cas.cz (gateway for redirection to kraken-M1)
• the port 7222 is used
• connection is only possible to the admin node “kraken”

In Linux, use the ssh command as follows:

ssh -Yp 7222 uživatel@zuul.it.cas.cz

The SSH client is not part of Windows and needs to be installed. The most commonly used client is PuTTY.

The PuTTY client is a client for SSH, Telnet, rlogin and plain TCP protocols. It is developed as open source software. The latest version can be downloaded here. The program consists of a single exe file, which you can place in e.g. the directory “c:\program files\putty”.

If you are going to run GUI programs (MATLAB) on the server, you must have an X server installed. The recommended one is VcXsrv Windows X Server, which is available in both 32-bit and 64-bit versions.

• 1. Run the putty program. In the Host name (or IP address) field, type zuul.it.cas.cz.
  In the Port field, type 7222.

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• 2. Go to the program configuration, tab Connection → SSH → Auth → X11. Check the Enable X11 forwarding.

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• 3. Return to the Session home tab and in the Saved Sessions field, type the name under which your session will be saved.
• 4. Click the Save button to save the configuration.
• 5. Use the Open button to start the connection.

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If you want to use programs with a graphical interface (e.g. MATLAB) on the server, you need to run VcXsrv X Server before connecting. Go to VcXsr in the programs menu and run the VcXsr program.

If the X server is running, its icon will appear in the tray.

• 6. A terminal window opens and login is initiated.
• 7. If you are logging in for the first time, a warning window appears. PuTTY does not “know” the remote server and asks if the server is trusted. Answer Yes.

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• 8. A terminal window opens and the login process begins. You will be prompted for a username and password. If you have entered both correctly, you will be logged in.

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• 9. If you are logging in for the first time, you need to change your password. To change your password, use the passwd command. You must first enter your current password.

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• 10. Then enter a new password. If the password you choose is too simple, the server will not approve the password and will prompt you to choose a more complex password.
• 11. You ask for the new password again to check it.