Logging Into login.discoverer.bg (from BG Academic IP Networks)

About

Important

This document explains how to access the login node of Discoverer HPC without establishing VPN Access.

If your desktop system or SSH jump server is connected to any of the Bulgarian academic/research networks, it can be possible to access the Dicoverer HPC login node directly, without establishing a VPN tunnel to the Discoverer HPC internal network. That opportunity is provided based on checking the IPv4 address affiliation and does not cover your home desktop systems.

In case you need SSH access to the Dicoverer HPC login node from your home desktop, then you should either establish VPN Access or use SSH jump server hosted on one of the Bulgarian academic/research networks.

How it works

Instead of connecting to login.discoverer.bg at port 22/tcp (that is the case with VPN Access), you should point your SSH client to login.bg.discoverer.bg at port 2222/tcp (mind ‘bg’ in the host name). Installed on login.bg.discoverer.bg is a firewall that restricts the connections to port 2222/tcp. It passes through only SSH connections initiated from IPv4 addresses affiliated to the Bulgarian academic/research network.

Prerequisites

To be able to access the login, node you should have:

  1. Valid and active Discoverer HPC account (see Onboarding guide)
  2. SSH client installed and SSH key-pair generated and stored (see SSH Access)
  3. (optional) SSH jump server, if you want to connect using your home desktop

Linux/macOS

Load your private SSH key into the memory (if it is not already loaded there):

ssh-add

Open a terminal and log into login.bg.discoverer.bg:

ssh login.bg.discoverer.bg -l username -p 2222

Windows (PuTTY)

Basic

Start your VPN client and establish a VPN tunnel to the Discoverer HPC internal network. See VPN Access.

Before running PuTTY, use Pageant to cache your SSH private key into the memory by following the procedure described in Caching Private SSH Keys.

To run PuTTY go to the seach bar of Windows, type there “putty” (1), and click on the application icon (2):

_images/putty_00.png

In the window of the application, be sure you are in the secion “Session” (1), then in the text field below “Host Name (or IP address)” type login.bg.discoverer.bg (2), be sure the port number is set 2222 (3), select “SSH” as a connection type (4), and press the button “Open” (5):

_images/putty_01_a.png

Upon first time connecting to login.bg.discoverer.bg on the current desktop Windows user profile, PuTTY will rise a warning window message and will display there the key algorithm (1) and the key fingerprint value (2) computed for of the server’s SSH key:

_images/putty_02.png

Warning

If the reported fingerprint value is not listed in the document login.discoverer.bg - Key Fingeprints, do not press “Accept” or “Connect Once” buttons. Press “Cance” and report the incident to the Discoverer HPC support team - see Getting help and wait for their response.

Then enter your username and press enter:

_images/putty_03_a.png

In case of successful login one should see the MOTD message, along with the shell environment command line:

_images/putty_04.png

Using a profile of settings

Start your VPN client and establish a VPN tunnel to the Discoverer HPC internal network. See VPN Access.

Before running PuTTY, use Pageant to cache your SSH private key into the memory by following the procedure described in Caching Private SSH Keys.

You can follow the instructions in Setting up a profile below to create your own PuTTY profile of settings for connecting to login.bg.discoverer.bg.

To run PuTTY go to the seach bar of Windows, type there “putty” (1), and click on the application icon (2):

_images/putty_00.png

From the list of profiles, select “login.bg.discoverer.bg” by clicking twice on it:

_images/putty_08_a.png

and PuTTY will initiate SSH connection to login.bg.discoverer.bg. In case of successful login one should see the MOTD message, along with the shell environment command line:

_images/putty_04.png

Setting up a profile

Run PuTTY by typing “putty” (1) in the Windows search bar, and click on the application icon (2):

_images/putty_00.png

In the left plane of the PuTTY window, click on “Connection” (1), mark there (if they are not) “Enable Naggle’s algorithm” and “Enable TCP keepalives” (2), and provide the number of seconds between two consequent keepalive messages (3), which for the example below is 60 seconds:

_images/putty_06.png

In “Data” (1) provide your Discoverer HPC username (2):

_images/putty_05.png

so as it can be automatically provided every time you log into login.bg.discoverer.bg. Finally, to save the profile settings, click on “Session”, type login.bg.discoverer.bg in the text field below “Host Name (and IP address)” (2), specify “2222” as port number (3), select “SSH” as connection type (4), type login.bg.discoverer.bg below “Saved Sessions” (5), and finally press “Save” to save the profile of settings under that name (6):

_images/putty_07_a.png

Getting help

See Getting help