• Manual server management
  • ➟ Documentation guidelines

...
├── env.template
├── 030HelloSshPublicKey
│   ├── main.tf
│   ├── providers.tf
│   ├── Readme.md
│   └── variables.tf
└── Modules
    ├── HostMetaData
        ...
    └── SshKnownHosts
         ...

export TF_VAR_login_user=devops
export TF_VAR_ssh_login_public_key=add_your_provider_token
export TF_VAR_hcloud_token=add_your_provider_token
export TF_VAR_dns_secret=add_your_ds_server_secret

To be copied, edited and used by Terraform.

• Manual server management
  • ➟ Hetzner cloud administration GUI

Protect your server by creating a firewall.

Upon hitting »Create and buy« you'll receive an E-Mail containing your server's IP and root password. You may otherwise reset root's password in the GUI's rescue tab.

$ ssh root@95.216.187.60
The authenticity of host '95.216.187.60 (95.216.187.60)' can't be established.
ED25519 key fingerprint is SHA256:vpV7B+l9RLQ+SwTMqtkk7YbICBhyhi2OP780+WVEFMY.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '95.216.187.60' (ED25519) to the list of known hosts.
root@95.216.187.60's password: 
You are required to change your password immediately (administrator enforced).
   ...
The list of available updates is more than a week old.
To check for new updates run: sudo apt update

Changing password for root.
Current password:
New password: 
Retype new password: 

321. Server creation
322. Server re-creation

• Manual server management
  • ➟ Using ssh
    • ➟ Public / private key pair

Solution: Create a public/private key pair.

$ ssh-keygen  -a 256 -t ed25519 ❶ -C "goik@hdm-stuttgart.de"
Generating public/private ed25519 key pair.
Enter file in which to save the key (/home/foo/.ssh/id_ed25519): 
Created directory '/home/foo/.ssh'.
Enter passphrase (empty for no passphrase): ❷
Enter same passphrase again: 
Your identification has been saved in /home/foo/.ssh/id_ed25519 ❸
Your public key has been saved in /home/foo/.ssh/id_ed25519.pub ❹
...

~/.ssh$ cd ~/.ssh
/home/foo/.ssh cat id_ed25519.pub >> authorized_keys ❶
mistudent@w10m:~/.ssh$ ls -al

drwxr-xr-x  2 student mi    0 Okt 17 17:45 .
drwxr-xr-x 32 student mi    0 Okt 17 17:44 ..
-rw-r--r--  1 student mi  396 Okt 17 17:45 authorized_keys ❷
-rw-------  1 student mi 1675 Okt 17 17:38 id_ed25519 ❸
-rw-r--r--  1 student mi  396 Okt 17 17:38 id_ed25519.pub ❹

goik@martin-hdm-desktop:~$ scp .ssh/id_ed25519.pub root@37.27.32.138:/tmp ❶
root@37.27.32.138's password: 
id_ed25519.pub                                     100%  103     3.7KB/s   00:00    
goik@martin-hdm-desktop:~$ ssh root@37.27.32.138 ❷
root@37.27.32.138's password: 
      ...
root@debian-4gb-hel1-2:~# cat  /tmp/id_ed25519.pub >> ~/.ssh/authorized_keys ❸
root@debian-4gb-hel1-2:~# exit ❹
goik@martin-hdm-desktop:~$ ssh root@37.27.32.138 ❺
     ...
Last login: Tue Apr  8 13:38:42 2025 from 141.62.31.244

323. Improve your server's security!

• Manual server management
  • ➟ Using ssh
    • ➟ Pass phrases and ssh agent

>ssh root@learn.mi.hdm-stuttgart.de
Enter passphrase for key '/home/goik/.ssh/id_ed25519': 
root@learn:~# exit
logout
Connection to learn.mi.hdm-stuttgart.de closed.
>ssh root@klausur.mi.hdm-stuttgart.de
Enter passphrase for key '/home/goik/.ssh/id_ed25519': 
root@klausur:~# exit
logout
Connection to klausur.mi.hdm-stuttgart.de closed.

>printenv |grep SSH_AUTH_SOCK
SSH_AUTH_SOCK=/run/user/21100/keyring/ssh
>ps aux|grep ssh-agent
goik        6671  ... /usr/bin/ssh-agent -D -a /run/user/21100/keyring/.ssh    
>ls -al /run/user/21100/keyring/ssh 
srwxr-xr-x. 1 goik goik 0 Apr 12 09:58 /run/user/21100/keyring/ssh

Note: The “s” in srwxr-xr-x indicates a domain socket.

324. ssh-agent installation
325. MI Gitlab access by ssh

• Manual server management
  • ➟ Using ssh
    • ➟ Agent forwarding

goik@local> ssh root@learn.mi.hdm-stuttgart.de
Linux learn 6.5.13-1-pve #1 SMP PREEMPT_DYNAMIC PMX 6.5.13-1 (2024-02-05T13:50Z) x86_64
...
root@learn:~# ssh klausur.mi.hdm-stuttgart.de
root@klausur.mi.hdm-stuttgart.de: Permission denied (publickey).

326. ssh host hopping

• Manual server management
  • ➟ Using ssh
    • ➟ Port forwarding

# Implicit for ssh-L localhost:2000:localhost:3306 ...
#
ssh -L 2000:localhost:3306 HostB # Mysql DB Server

# Originating host
#
$ telnet localhost:2000
Trying ::1...
Connected to localhost.
Escape character is '^]'.
DHost '127.0.0.1' is not allowed
to connect to this MariaDB server

327. ssh port forwarding

• Manual server management
  • ➟ Using ssh
    • ➟ X11 forwarding

328. ssh X11 forwarding

• Manual server management
  • ➟ Using ssh
    • ➟ Network data transfer using scp, rsync and ssh

$ md5sum README.md
64e1d4b7f8fbf99219020b5e931db986  README.md

$ scp README.md root@www.medieninformatik.cloud:/tmp
README.md
                                           
$ ssh root@www.medieninformatik.cloud
Last login: Mon Oct 13 13:58:12 2025 from 141.62.20.174

root@applix:~# md5sum /tmp/README.md 
64e1d4b7f8fbf99219020b5e931db986  /tmp/README.md

$ tree hello
hello/
├── pom.xml
└── src
    └── main
        └── java
            └── start
                └── App.java

$ rsync -av --delete -e ssh hello root@www.medieninformatik.cloud:/tmp
sending incremental file list
hello/
hello/pom.xml
hello/src/
hello/src/main/
hello/src/main/java/
hello/src/main/java/start/
hello/src/main/java/start/App.java

sent 3,115 bytes  received 82 bytes  2,131.33 bytes/sec
total size is 2,769  speedup is 0.87

329. Directory transfer by rsync and ssh

• Manual server management
  • ➟ Prerequisites

Bash Guide for Beginners

The definitive guide, also available at SafariOnline

330. Enabling index based file search
331. Using the tail -f command
332. Using journalctl

• Manual server management
  • ➟ Ubuntu / Debian Package management
    • ➟ Prerequisites

Problems: