Internet Printing with Tor: A Real-World Solution
Introduction
When people hear “Tor,” they often think of hidden or illicit activities. However, Tor is actually a privacy-focused tool with many legitimate applications. One of these involves sending print jobs over the internet to thermal printers, even when networks have strict firewall rules. In this article, we explain how we combined Tor, Raspberry Pi devices, and Onion services to create a reliable system that bypasses complex networking issues—without compromising security.
The Challenge
A client wanted to send thermal print jobs to remote locations. Yet, they faced locked-down networks with minimal access to external connections. Moreover, they didn’t want to open ports or configure VPNs. They needed an easy solution:
- No firewall changes
- No complex routing
- Fast, on-demand printing
Initially, we considered a polling system, which would periodically check for print jobs. However, polling adds server load and delays. Instead, we chose Tor for its ability to establish outbound connections from within any network.
Our Tor-Based Solution
1. Custom Raspberry Pi Image
We set up a Raspberry Pi for each printer. First, it launches a simple Wi-Fi hotspot for initial network configuration. Next, it automatically connects to Tor and registers with our central server. As a result, users avoid tinkering with firewall rules.
2. Onion Services
Once online, the Pi creates an Onion address. This address allows the central server to push print jobs to the Pi through Tor. Therefore, inbound firewalls don’t matter, because the Pi always maintains the outbound connection to Tor.
3. Client Certificates for Security
We added client certificates to lock down who can access each printer’s Onion service. In essence, only the central server holds valid certificates, so even if someone discovers the Onion address, they can’t connect without the right credentials.
4. Automatic Setup & Maintenance
Users only need to power on the Pi and configure Wi-Fi. After that, everything else—onion service registration, secure connections, and certificate exchange—happens automatically. Consequently, it’s easy to scale and maintain.
Why Tor Works Well
- Outbound Connections
Tor establishes outbound tunnels, which most networks allow. Hence, the Pi can “punch out” of strict firewalls while staying secure. - Strong Privacy & Security
Onion services keep printers hidden from direct public exposure. Furthermore, client certificates add another layer of protection. - Minimal Configuration
End users don’t have to open ports or run VPN clients. Instead, they rely on the Pi’s seamless integration with Tor. - No Network Overlap
Unlike solutions like Tailscale, each Pi remains isolated. Therefore, if one node is compromised, it can’t affect the others. - Consistent Performance
While Tor can be slow for heavy web browsing, it handles small print jobs with ease and reliability.
Real-World Impact
By harnessing Tor and Raspberry Pi devices, our client now prints instantly over the internet without worrying about firewall restrictions or complex setups. As a result, their thermal printing workflow is faster and more efficient. Additionally, they enjoy peace of mind, knowing each printer is secure behind Onion services and certificates.
Conclusion
Tor isn’t just for private browsing—it’s also a practical tool for bypassing firewall limitations and ensuring secure data transfer. With the right configuration and an automated Raspberry Pi setup, you can send print jobs anywhere, no matter how strict the network.
Ready to explore a Tor-based solution for your own needs? Contact us to learn how we can help you build a secure, reliable system that streamlines your remote printing or other mission-critical tasks.
