Linux administration

This course offers a comprehensive introduction to the functionality of modern IT infrastructures with a particular focus on the technical fundamentals. Participants learn to understand and configure central IT services such as email servers (Postfix, Dovecot), name resolution (DNS), web servers (Apache, Tomcat), remote services (SSH), file servers and DHCP. In addition, the network infrastructure and the structure of IT systems are covered in detail, including common vulnerabilities and security gaps.

• aspiring IT security consultants, pentesters and red teamers
• prospective system administrators and network technicians
• IT professionals who want to expand their technical knowledge
• IT leaders who want to build a deeper technical understanding

1. Basics of Networks:

   • Communication protocols: TCP/IP, UDP, ICMP

   • Network services: DHCP, DNS, NAT and their role in IT environments

   • routing network segmentation

2. Remote Services: SSH

   • Secure remote access with SSH

   • Best Practices for SSH Server Configuration and Key Management

   • Securing SSH services: port knocking, MFA

3. DHCP server:

   • How DHCP works and its role in the network

   • DHCP protocol and configuration options

   • Securing DHCP servers: IP address reservations and secure configuration

   • Misconfigurations and their impact on network security

4. Name resolution: DNS (Bind/DNS)

   • Structure and Function of DNS

   • DNS protocol and security risks (DNS spoofing, cache poisoning)

   • Configuration of a Bind/DNS server and security mechanisms

   • Typical mistakes and best practices for securing DNS servers

5. Email servers: Postfix & Dovecot

   • Introduction to email services: Postfix as MTA, Dovecot as IMAP/POP3 server

   • SMTP, IMAP, POP3 and their security risks

   • Security mechanisms: SPF, DKIM, DMARC, SSL/TLS

   • Best Practices for Hardening Email Servers

6. Web / HTTP (Apache / Tomcat)

   • Structure and function of web servers (Apache HTTP Server, Tomcat)

• Protocols: HTTP, HTTPS and their role in web communication

• Securing web servers: SSL/TLS, secure configuration

• Practical examples of configuration errors and security risks

7. file server (Samba/NFS)

• Structure and Function of File Servers: Samba and NFS

• File sharing and permissions: configuration options and best practices

• Security risks with insecure file servers: authorization problems, unprotected shares

• Securing file servers: rights management, encryption and authentication

• Typical vulnerabilities in file server environments and how to fix them

8. Containers and Automation

   • Introduction to containerization and using Docker for system administration

   • Automating administrative tasks with shell scripts and Ansible

5 days, 8 hours per day

The course includes both theoretical units and practical exercises in a laboratory environment. Participants learn to identify and fix real-world vulnerabilities by analyzing and fixing various configuration errors.

Basic knowledge of IT and networks is recommended, but no specific prior knowledge of IT security is required.