# Denis Hierholzer – Resume

IT Systems Engineer. Focus: AI, Network, Security, Windows & Linux Servers. Location: Klettgau, Germany. Website: https://www.hierholzer.us

## Profile

Since 2007 I have worked as a Systems Engineer, focusing on Windows servers, Active Directory, backup, virtualization, patch management and monitoring. I also work with Linux servers, develop small applications and plugins (Python, C#, Java) and love automating tasks with scripting (PowerShell, Bash, Batch, VBS).

For some time now I have been working with AI, both cloud-based and local, for coding, retrieval-augmented generation (RAG), agents and more. I write detailed technical documentation for administrators and end users.

Continuing education matters to me, which is why I regularly earn certifications and attend IT courses. I am proactive, punctual and highly organized. In my spare time I extend my own IT lab and explore new applications and services.

## Experience

### IT Infrastructure Engineer – Cilag AG – a Johnson & Johnson company (Mar 2021 – Present)
Schaffhausen, Switzerland. Engineering and administration of the entire Schaffhausen OT infrastructure (LAN, firewalls, Linux and Windows servers, SAN).
- Active Directory
- Application streaming
- Artificial Intelligence (AI)
- Backup and archiving
- Cisco ACI, classic routing and switching
- Scripting (PowerShell and others)
- Application development (Python)
- Virtualization
- OT cyber security (micro-segmentation, vulnerability management)
- Project: Introduction of Cisco ACI. Replaced the Cisco SG500 core with an ACI spine/leaf fabric and introduced a new security zoning concept.
- Project: Introduction of Veritas NetBackup. NetBackup 9.1 on Red Hat 8.5 with a Dell ML3 tape library, iSCSI SAN, deduplication and tape encryption.

### IT Systems Engineer – Syntegon Technology Services AG (Jun 2020 – Feb 2021)
Beringen, Switzerland. Engineering and coordination of multiple infrastructure projects with a focus on networking (WAN, LAN, WLAN, DMZ, firewalls) and automation with PowerShell.

### Lead Network and Security – Schroder & Co Bank AG (Jun 2014 – May 2020)
Zurich, Switzerland. IT Operations department.
- Administration and installation of Windows, Solaris, network and security systems
- Operation of the T24 core banking application
- VMware infrastructure including automated failover
- System Center (SCCM, SCOM)
- Security systems (DRM, DLP, Palo Alto and Check Point firewalls, privileged access management)
- Process automation with PowerShell, e.g. a user account lifecycle tool
- Project: Automated disaster recovery. Automatic failover of the virtual infrastructure to the DR site.
- Project: Firewall migration. Migrated proxy rules from Blue Coat ProxySG 600-20 to Palo Alto 5020 with Panorama and reduced the rule base by more than 50%.
- Project: User lifecycle automation. Modular PowerShell automation for user termination with HR/AD synchronisation and password-expiry notifications.
- Project: Data classification and encryption. AD RMS-based file classification and encryption (IQProtector) to meet FINMA requirements.
- Project: AppLocker rollout. AppLocker rollout with a self-developed GUI tool "AppLocker Mgmt Pro" that writes events to SQL Server.
- Project: PowerShell tooling. About ten tools, including a GUI for folder permissions, weekend wake/shutdown, RSA token provisioning, an Outlook button for SCSM tickets and the help desk tool "TSTool3".
- Project: Infrastructure modernisation. Migrated VBS logon scripts to group policies and DHCP to Windows Server 2012 R2.

### Senior Systems Administrator / Systems Engineer – Dentsu Holdings USA / 360i (Dec 2012 – Mar 2014)
New York City, USA. Corporate IT managing about 10 branches and more than 300 servers worldwide in a mixed Windows/Linux environment.
- Windows and Linux servers, VMware vSphere, Active Directory
- SCCM, WSUS, McAfee ePO
- Redmine, Atlassian Jira and Confluence
- EMC NetWorker, Microsoft Exchange
- Microsoft SQL Server including clustering, Apache Subversion including replication
- Several PowerShell and VBS applications
- Project: Active Directory maintenance framework. Modular framework with more than 1,500 lines of code.
- Project: Client management at scale. SCCM 2012 for 800+ workstations; WSUS for about 150 servers and 900+ workstations at 10 sites.
- Project: BitLocker. Disk encryption managed with SCCM, TPM and Active Directory.
- Project: More. Introduced Redmine, SQL Server failover cluster, McAfee anti-virus infrastructure, server inventory application, WordPress and SilverStripe site migration.

### IT Officer – Bomatec AG (Jan 2011 – Oct 2012)
Höri, Switzerland. Responsible for all IT including project management.
- Network services, help desk, newsletter operations
- Windows 7 clients, Windows Server 2008 R2
- Exchange 2010, Lync 2010, SQL Server
- SAN, backup and ERP systems
- Project: Windows 7 migration. Migration to Windows 7 64-bit with SCCM.
- Project: Backup concept. Grandfather-father-son backup with Symantec Backup Exec 2012 and an HP tape autoloader.
- Project: More. Wi-Fi improvements and a new newsletter process.

### Systems Administrator / Systems Engineer – Bucher Hydraulics (Sep 2007 – Dec 2010)
Klettgau, Germany. Central IT managing 16 branches and about 100 servers worldwide.
- Entire Lotus Notes / Domino infrastructure including the migration from version 7 to 8
- Development and improvement of Notes applications
- Project: Infrastructure projects. Corporate mobile device concept, P2V server migrations, video conferencing, Trend Micro anti-virus, WSUS patch management and an AD migration after a takeover.

## Before graduation

### Web Developer (Diploma Thesis) – eschbach IT GmbH (Mar 2007 – Aug 2007)
Bad Säckingen, Germany. Diploma thesis "Conception and implementation of a Rich Internet Application based on an existing intranet application" (PHP, AJAX), the basis of today's Shiftconnector.

### Systems Administrator (Student Apprentice) – Micronas GmbH (Mar 2006 – Aug 2006)
Freiburg, Germany. Network administration, second-level support, server administration, scripting.

### Systems Administrator and First-Level Support (Student Apprentice) – Harman/Becker Automotive Systems GmbH (Sep 2004 – Feb 2005)
Stuttgart area, Germany. Network administration, first-level support, application development.

### Database Developer (Freelance) – Textilbüro Weissenberger GmbH (Aug 2002 – Sep 2002)
Klettgau, Germany. Microsoft Access database for order processing.

## Volunteer work

### Volunteer Systems & Web Administrator – Gemeindebücherei Klettgau (public library) (Jan 2002 – Jul 2020)
Klettgau, Germany. User support, system administration (Windows Small Business Server 2003, Exchange, library software), and development of the public website. Officially honoured for volunteer work in January 2017.

## Education

- Diplom-Informatiker (FH) (BSc equivalent), Hochschule Furtwangen University, Computer Networking, 2003–2007, grade 1.8 (A-)
- Abitur (German university entrance qualification), Gewerbliche Schulen Waldshut – Technical High School (Information Technology), Information technology, 2000–2003, grade 1.9 (A-)

## Certifications

- Nov 2026: Claude Code Masterclass – verify: https://zertifizierung.kiberatung.de/verify/8d17447f-9c4e-44f2-9295-4a51f7f7262f
- Nov 2025: CISSP – Certified Information Systems Security Professional (ISC2) – verify: https://www.credly.com/badges/df414fc9-98eb-4e39-82e5-4562b5ccb1ba/public_url
- May 2024: Fitness Trainer B-License
- Jul 2019: Cisco Certified Specialist – Enterprise Core (Cisco) – Passed CCNP SWITCH (300-115) and CCNP ROUTE (300-101)
- Nov 2018: LPIC-1 Linux Administrator (Linux Professional Institute) – verify: https://www.lpi.org/v/LPI000278048/bc3atl5nuw
- Aug 2018: Check Point Certified Security Administrator (CCSA) R80 (Check Point)
- Feb 2017: Palo Alto Networks Accredited Configuration Engineer (ACE) PAN-OS 7.0 (Palo Alto Networks)
- Nov 2016: Cisco Certified Network Associate Security (CCNA Security) (Cisco) – Exam 210-260, NSA CNSS 4011 recognition
- Apr 2016: Certified Ethical Hacker (CEH v9) (EC-Council) – Recertified, valid until April 2028 – verify: https://aspen.eccouncil.org/Verify
- Nov 2015: Oracle Certified Associate, Oracle Solaris 11 System Administrator (Oracle)
- Jan 2015: Intensive Course Banking Fundamentals (Fachschule für Bankwirtschaft)
- Dec 2013: Cisco Certified Network Associate Routing & Switching (CCNA R&S) (Cisco)
- Nov 2013: Cisco Certified Entry Networking Technician (CCENT) (Cisco)
- Nov 2013: VMware Certified Associate – Data Center Virtualization (VCA-DCV) (VMware)
- May 2012: Microsoft Certified Solutions Associate – Windows Server 2008 (MCSA) (Microsoft)
- May 2012: Microsoft Certified IT Professional – Server Administrator (MCITP:SA) (Microsoft)
- Aug 2010: IBM Certified System Administrator – Lotus Notes and Domino 8.5 (IBM)
- Dec 2009: Cambridge Certificate in Advanced English (C1) (University of Cambridge)
- Oct 2009: IBM Certified System Administrator – Lotus Notes and Domino 8.0 (IBM)
- Sep 2008: Certified Data Protection Officer (IHK) (IHK)

## Independent coursework

- Oct 2024: Proxmox VE Installation and Administration & Proxmox VE Advanced
- Nov 2021: Red Hat Ansible for Network Automation (DO457)
- Nov 2021: First Aid Training for Company First Responders
- Jan 2020: Check Point Certified Security Expert R80.20 (CCSE)
- Jan 2020: immocation Masterclass – Building Wealth with Real Estate
- Sep 2019: Management Essentials Training (coaching, change and performance management)
- Jun 2019: Cisco Implementing Cisco IP Routing (ROUTE 1.0)
- Mar 2019: Cisco Implementing Cisco IP Switched Networks (SWITCH 2.0)
- May 2018: Check Point Cyber Security Administrator R80.10
- Nov 2017: Tanium 7 Foundation, Operations & IR Deep Dive
- Feb 2017: Palo Alto Networks Firewall: Install, Configure, and Manage (EDU-201)
- Jan 2014: PowerShell for the IT Administrator, Part 2 (Microsoft WorkshopPLUS)
- Jul 2013: PowerShell for the IT Administrator, Part 1 (Microsoft WorkshopPLUS)
- Mar 2013: Microsoft SQL Server 2008 Administration
- Jun 2011: Planning, Deploying and Managing Microsoft SCCM 2007 (MOC 6451)
- May 2011: OpaccOne for System Administrators (ERP)
- Apr 2011: Microsoft Office 2010

## Languages

- German: Native speaker
- Swiss German: Native speaker
- English: Full professional proficiency (C1)
- French: Basic knowledge

## Personal commitment

- 2013 – 2014: Organizer, New York City German Culture Meetup Group
- 2005 – 2006: Student President, IT Faculty, Hochschule Furtwangen University

## Preferred work location

Within a radius of about 50 km around Klettgau, Germany, including Schaffhausen, Zurich and Winterthur.

Reference letters are available on request.