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====== Connecting to the system ======

Hábrók can be reached through a protocol called SSH (secure shell). The secure in the name implies that the network traffic is encrypted. This means that other people on the network cannot listen in to your username, password, any commands and data transfers that you have between your system and the Hábrók nodes.

In order to access the system an SSH client is required. For this several options are available.
  - Client program ([[windows|Windows]])
  - Terminal commands ([[macos|Mac OS X]] and [[linux|Linux]])
  - [[web_portal|Web portal]] (from any system)

===== Hostnames =====

When using a client program or a terminal you'll need to know about which system to connect to. Hábrók has five so-called login nodes you can connect to:
  - login1.hb.hpc.rug.nl
  - login2.hb.hpc.rug.nl
  - interactive1.hb.hpc.rug.nl
  - interactive2.hb.hpc.rug.nl
  - gpu1.hb.hpc.rug.nl
  - gpu2.hb.hpc.rug.nl

The different capabilities of these machines will be described later. But for accessing the system in order to edit files, submit jobs, and move around data all of them can be used.

===== Login credentials =====

The second thing you need to know is the username. For these systems your university account number and password are being used. **For the account name you have to use lowercase p,s or f!** Logging in also includes providing a token for multi-factor authentication. This token will be requested once every 8 hours, when connecting to the same system with the same username from the same location. You can use the same kind of tokens that you always use for your university account (usually provided by an authenticator app on your phone).

====== Details for different operating systems & Web portal ======

The ways to connect from different operating systems are described on the following pages:
   - [[windows]]
   - [[linux]]
   - [[macos]]

There is also a web interface available to the system, which offers a command line interface, a file editor, and file browser:
   - [[web_portal]]

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**Next section: [[..:command_line:working_on_the_command_line_-_part_1]]**