When a business operates across multiple countries and management systems, email, and employee workspaces must be accessible from anywhere, the question of "where and how to host everything" shifts from a technical issue into a strategic one. This case study demonstrates how a turnkey remote infrastructure was built for an auto repair shop network: a single dedicated server in Frankfurt, a fully open-source stack, and secure access for international employees – without the burden of Windows Server, MS SQL Server, or RDS CAL licensing costs for the client.
Context
The client is an entrepreneur who relocated to Poland and expanded his business there: today, his auto repair shop chain operates in multiple countries – both in the new Polish market and in his home market, where the business originated. For operational and management accounting (vehicle check-in, work orders, spare parts warehouse, mutual settlements), the company uses the BAS Auto Repair accounting system, running on top of the BAF technology platform. The client already owned the platform and configuration licenses, managing the application layer independently with an in-house Lead IT Specialist.
INTROSERV was responsible for the rest of the infrastructure: server hardware, virtualization, DBMS, remote desktop access for international staff, backups, email, and the network perimeter. The previous system was extremely simple, and in-house specialists were sufficient. However, the new infrastructure required expertise of a completely different level.
The Task
The main complexity lay not in the accounting system itself, which the client configured independently, but in assembling a production-grade infrastructure built on open-source software that could be maintained smoothly without constant IT intervention.
Many integrators take the path of least resistance in such projects: Windows Server + MS SQL Server topped with an RDS terminal server and user CALs. For an auto repair shop chain with a small team, this stack is redundant and cost-prohibitive. The BAF platform officially supports PostgreSQL, which opened the door to a complete rejection of Microsoft licenses.
The project required deploying a hypervisor and a dedicated backup server, properly isolating PostgreSQL to guarantee database backup consistency, setting up secure remote access, and migrating the client's existing mail infrastructure. Everything had to remain transparent and manageable: the client receives a ready-to-use platform and continues managing the application layer independently.
Infrastructure Configuration
Main node: A dedicated server in Frankfurt featuring a 24-core AMD EPYC™ processor , 128 GB RAM, and two storage arrays (2×500 GB SSDs for the OS and 2×2 TB SSDs for data), both running in ZFS mirrors. The server runs Proxmox VE 9.2 – the latest version of the open-source virtualization platform based on Debian 13 with native ZFS support.
Connected over the local network is a second server running Proxmox Backup Server: 8 cores, 32 GB RAM, 2×500 GB SSDs for the OS, and 2×4 TB SSDs for backup storage. Moving the backup server to a dedicated machine was a deliberate decision: a failure of the main node must not compromise backup integrity.
Logical Layout
At the entry point – an OPNsense software router and firewall with VPN termination; all external access goes exclusively via VPN.
The main Proxmox VE node hosts the virtual machines: VM #1 (Debian, BAF server + PostgreSQL) – core accounting system; VM #2 (Debian with KDE and ThinLinc web interface) – remote desktop server; VM #3 (Portabase) – database backup segment; a separate VM – Carbonio CE mail server; VM #5 OPNsense – software router.
The PBS server receives backups of all VMs over the local network.
Employees from different countries connect via VPN and work in the accounting system via ThinLinc desktop.
Solution
INTROSERV engineers designed the infrastructure around the "one isolated VM per service" principle, making maintenance, backup management, and access control much simpler.
- Accounting Core on PostgreSQL. VM #1 (Debian) runs the BAF server and PostgreSQL instead of the traditional Windows Server + MS SQL bundle. The client installed the BAS configuration on top of this core independently.
- Remote Access via ThinLinc. VM #2 runs Debian with a KDE desktop environment and Cendio ThinLinc terminal server. Employees connect using a native client or directly through a web browser. ThinLinc is free for up to 10 concurrent users – a perfect replacement for RDS in small teams. User accounts were created according to specifications, with room for the client to add licenses as the team grows.
- Two-Tier Backups. PostgreSQL backup management is isolated on a dedicated VM running Portabase – an open-source tool for centralized database backup management complete with scheduling, retention policies, and an agent-based secure-by-design architecture. Concurrently, all virtual machines are backed up to the dedicated Proxmox Backup Server, utilizing incremental deduplicated backups and client-side encryption.
- Perimeter Security on OPNsense. The OPNsense software router and firewall terminates all VPN connections: neither RDP nor web management interfaces are exposed to the public internet – all remote access passes through a secure tunnel.
- Email Migration to Carbonio CE. The most delicate challenge was migrating the mail server from the client's previous host to Carbonio Community Edition. Transferring mailboxes and message history with zero data loss is always a high-precision operation, where INTROSERV sysadmins' experience was essential. All other implementation phases proceeded routinely.
The fully configured platform was handed over to the client, who took over application tuning and ongoing management of the accounting software.
Turnkey Infrastructure as an Economic Strategy
Rather than a disconnected set of services, the client received a cohesive, production-ready system featuring isolated VMs, two-tier backups, and a closed VPN perimeter – all with zero Microsoft licensing fees.
For comparison, a standard proprietary stack (Windows Server Standard, MS SQL Server Standard, RDS CALs for ~10 users) would cost approximately $6,000–$11,000 upfront, excluding mandatory upgrade licenses in future releases. Instead, the solution utilizes PostgreSQL over MS SQL, ThinLinc over RDS, Proxmox VE and PBS over paid virtualization and backup software, and OPNsense and Carbonio CE over commercial counterparts.
Direct software savings are only part of the value. The project delivered several key business benefits:
Single point of accountability – hardware and system administration services provided by a single company. The client did not need to vet outsourced admins or coordinate between a host and third-party engineers: INTROSERV engineers took end-to-end responsibility for infrastructure setup and performance.
Fast time-to-market – the entire infrastructure, from hypervisor and DBMS to the mail server and VPN perimeter, was deployed and handed over into production within one week.
Continuous support – ongoing maintenance is handled by the same engineering team that designed and deployed the environment and understands its architecture inside out.
Predictable budget – the only paid software components are the client's existing BAF and BAS licenses. The infrastructure stack generates zero recurring software license fees during deployment or future updates.
Looking to deploy an accounting or ERP system on a cost-predictable open-source stack? The INTROSERV team can conduct an infrastructure audit, select optimal hardware, and deliver a turnkey solution – from hypervisor to backup strategy.
