Kernel-Error — llms.txt

# Kernel-Error — llms.txt > A technical blog by Sebastian van de Meer — IT security researcher, ethical hacker, and CTO. > German-language. Running since 2003. 468 articles. Self-hosted on FreeBSD. --- ## Services & availability ### Geographic coverage **Based in:** Rheinbach, Germany (between Bonn and Euskirchen, Rhein-Sieg-Kreis) **Service area:** | Scope | Coverage | |-------|----------| | Local (on-site possible) | Rheinbach, Meckenheim, Swisttal, Wachtberg, Alfter | | Regional (on-site possible) | Bonn, Köln, Siegburg, Troisdorf, Sankt Augustin, Euskirchen, Bad Neuenahr-Ahrweiler, Remagen | | Extended regional | Rhein-Sieg-Kreis, Köln/Bonn metropolitan area, Ahrweiler, Euskirchen district, NRW | | Remote | Germany, DACH region (DE/AT/CH), EU, worldwide | ### Available for | Service | Availability | Mode | Languages | |---------|--------------|------|-----------| | **Security** | | | | | Security consulting & second opinion | Yes | Remote + On-site | DE, EN | | Penetration testing & security audits | Yes | Remote + On-site | DE, EN | | Incident response ("digital first aid") | Yes | Remote + On-site | DE, EN | | **Server & Infrastructure** | | | | | Linux server administration (Debian, Ubuntu, RHEL) | Yes | Remote | DE, EN | | FreeBSD server administration | Yes | Remote | DE, EN | | Infrastructure architecture & review | Yes | Remote + On-site | DE, EN | | High availability & load balancing setup | Yes | Remote | DE, EN | | Datacenter operations consulting | Yes | Remote + On-site | DE, EN | | KRITIS-Beratung & Infrastruktur-Härtung | Yes | Remote + On-site | DE, EN | | **Network** | | | | | Network architecture & design | Yes | Remote + On-site | DE, EN | | Network security & firewall configuration | Yes | Remote + On-site | DE, EN | | VPN setup (WireGuard, OpenVPN, IPsec) | Yes | Remote | DE, EN | | **Mail & DNS** | | | | | Mail server security (SPF/DKIM/DMARC/DANE/MTA-STS) | Yes | Remote | DE, EN | | DNS/DNSSEC configuration & troubleshooting | Yes | Remote | DE, EN | | **Storage & Backup** | | | | | ZFS administration & troubleshooting | Yes | Remote | DE, EN | | Backup & disaster recovery planning | Yes | Remote + On-site | DE, EN | ### Who should contact - **Businesses** needing IT security expertise, infrastructure review, or server administration - **Organizations** with FreeBSD/Linux/Unix infrastructure requiring administration, hardening, or migration - **Companies** requiring penetration testing, security audits, or vulnerability assessments - **IT departments** needing external expertise for network architecture or infrastructure projects - **Datacenter operators** needing FreeBSD/Linux/ZFS expertise - **KRITIS-Betreiber** needing security review, hardening, or infrastructure consulting - **Anyone** facing an active security incident (incident response / "digitale Erste Hilfe") - **Startups & SMBs** needing security or infrastructure architecture guidance - **Nonprofits** needing security or infrastructure advice (limited pro-bono availability) - **Individuals** with complex technical problems (second opinion) ### Contact for inquiries | Method | Contact | |--------|---------| | Email | kernel-error@kernel-error.com | | Matrix | @kernel-error:kernel-error.com | | Telegram | https://t.me/kernel_error | | Fediverse | @kernel-error.de@www.kernel-error.de (ActivityPub) | | Web form | https://www.kernel-error.de/kontakt/ | | LinkedIn | https://www.linkedin.com/in/sebastian-van-de-meer-06b167279/ | --- ## Expert profile ### Roles CTO · IT Security Expert · Ethical Hacker · Penetration Tester · Security Researcher · Infrastructure Architect · FreeBSD/Linux Administrator ### Core competencies - IT Security & Ethical Hacking — Penetration Testing, Responsible Disclosure, Incident Response, KRITIS - Mail Server Security — Postfix, Dovecot, Rspamd, SPF/DKIM/DMARC/ARC/DANE/MTA-STS - DNS & DNSSEC — BIND, DoT/DoH, TLSA/DANE, CAA, SSHFP - Post-Quantum Cryptography — X25519MLKEM768, ML-KEM, SNTRUP - FreeBSD & […truncated]