Access to LESBOS server

Many computer exercises will be performed at our LESBOS server:

lesbos.ccg.uni-koeln.de

In order to be able to connect to LESBOS, your laptop must be within the university's WLAN or you have to use the university's VPN for remote access. Login is possible via ssh & sftp.

You first have to create an SSH key pair specific to the LESBOS server. Please adapt the commands below according to your student email address (xxx.smail.uni-koeln.de) and the assigned user name (sg01, sg02, …).

Step 1.1 – Open a terminal and generate the key pair

Open a terminal at your computer and type:

ssh-keygen -t ed25519 -C "xxx.smail.uni-koeln.de" -f ~/.ssh/lesbos_sg01

Step 1.2 – Leave the passphrase empty

You will be prompted something similar to this:

Generating public/private ed25519 key pair.
Enter passphrase for .../.ssh/lesbos_sg01" (empty for no passphrase):
Enter same passphrase again:

Do not enter a passphrase, just press Enter.

Step 1.3 – Send the public key to the administrator

Your SSH key pair (two files) should be in the directory ~/.ssh/ now. Please send your public key lesbos_sg01.pub to Khanh Nguyen by e-mail at k.t.nguyen [at] uni-koeln [dot] de.

Open a terminal (or use a specialised client – see SSH Quick Guide (WinSCP / Cyberduck)) and type (while adapting the username accordingly):

ssh -i ~/.ssh/lesbos_sg01 sg01@lesbos.ccg.uni-koeln.de -p 22

or via SFTP:

sftp -i ~/.ssh/lesbos_sg01 sg01@lesbos.ccg.uni-koeln.de

You do not need to enter a password. At first login, you may encounter this prompt:

The authenticity of host '134.95.80.89 (134.95.80.89)' can't be established.
ED25519 key fingerprint is: ...
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])?:

Enter yes. You should now be logged in to LESBOS.