Add comprehensive guide for securing Raspberry Pi from A-Z

- Introduced a detailed tutorial on securing Raspberry Pi, including SSH access, user management, firewall configuration, and automatic updates.
- Included commands and steps for changing default user, setting up UFW firewall, and installing Fail2Ban for brute force protection.
- Provided links to related video tutorials and blog posts for further learning.
- Ensured the guide is structured for clarity and ease of understanding for users of all levels.

Author: marci

content/posts/linux/linux-server-absichern.de.md

@@ -25,7 +25,7 @@ keywords:
 ---
 > **Wer unter euch seinen Raspberry Pi absichern möchte, der findet hier die entsprechende Anleitung:**
 >
-> https://secure-bits.org/raspberry-pi-absichern-von-a-z-2023/
+> http://localhost:1313/posts/privacy/pihole/pihole-absichern-von-a-z/
 
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