Managed Nebula vs OpenVPN

Managed Nebula and OpenVPN solve connectivity problems in fundamentally different ways. OpenVPN is a traditional VPN that routes traffic through a central server. Nebula is a mesh networking platform where hosts connect directly to each other, with no central bottleneck.

Nebula is a fully open-source overlay networking tool that we originally built at Slack and continue to maintain at Defined Networking. It uses its own protocol built on the Noise framework to create peer-to-peer encrypted tunnels between hosts. Managed Nebula is our cloud-hosted management layer that handles certificate authorities, host configuration, and distribution, while you retain full control of your network’s data plane.

OpenVPN is one of the most widely deployed VPN solutions. It creates encrypted tunnels using TLS/SSL and typically operates in a hub-and-spoke topology where all traffic routes through a central VPN server.

For an introduction to how mesh networks differ from traditional VPNs, see our blog post on VPNs vs. mesh networks.

	Managed Nebula	OpenVPN
Topology	Peer-to-peer mesh	Hub-and-spoke (centralized)
Protocol	Nebula (Noise IX)	OpenVPN (TLS/SSL)
Encryption	ChaCha20-Poly1305	AES-256-GCM or ChaCha20
Authentication	Certificate-based (Nebula CA)	Certificate or username/password
Firewall	Stateful with security groups	Server-side firewall rules
NAT traversal	Automatic via Lighthouses	Requires port forwarding
Single point	No central bottleneck	All traffic through VPN server
Open source	Fully (MIT license)	Community (GPLv2) + commercial
Free tier	Up to 100 hosts	Community edition (self-managed)
Pricing	$1/host/month	Per-connection pricing

This is the most significant difference between the two tools.

Nebula creates a mesh network where every host can communicate directly with every other host. There is no central server that all traffic must pass through. When host A needs to talk to host B, they establish a direct encrypted tunnel between themselves. This means latency is minimized (traffic takes the shortest path), there is no single point of failure, and bandwidth scales naturally as you add hosts.

OpenVPN typically operates in a hub-and-spoke model. All traffic from remote clients flows through a central VPN server. If host A needs to talk to host B, the traffic goes from A to the VPN server, then from the VPN server to B. This creates a central bottleneck for bandwidth, a single point of failure, and added latency for host-to-host communication.

The architectural difference has a direct impact on performance.

Nebula connections are peer-to-peer. Traffic between two hosts takes the most direct network path available, with encryption handled at each endpoint. There is no central server that must process all traffic. We can saturate a 10 Gbps network on modern CPUs, and we publish our benchmarking results publicly.

OpenVPN traffic must pass through the VPN server, which becomes the bottleneck. The server must encrypt and decrypt all traffic for all connected clients. As the number of clients grows, the VPN server’s CPU and bandwidth become limiting factors. OpenVPN also uses a userspace TLS implementation, which generally has higher per-packet overhead than Nebula’s Noise-based protocol.

Nebula uses certificate-based authentication with its own simplified certificate format. Adding a new host only requires signing a new certificate. Existing hosts do not need to be reconfigured. Managed Nebula handles the CA and certificate lifecycle for you, and we support single sign-on (SSO) on all plans, including the free tier.

OpenVPN supports both certificate-based and username/password authentication. Certificate management with OpenVPN typically requires managing a full PKI infrastructure (using tools like easy-rsa), which adds operational complexity. Commercial OpenVPN solutions (Access Server, CloudConti) add management UIs but at additional cost.

Nebula has a stateful packet firewall built directly into the Nebula process. Firewall rules can reference groups embedded in certificates, working similarly to AWS Security Groups. This distributed firewall runs on every host and does not depend on a central server.

OpenVPN access control is typically implemented at the VPN server level using server-side firewall rules, routing tables, and client configuration directives. Since all traffic passes through the server, the server is the natural enforcement point. This means access control depends entirely on the VPN server being available and correctly configured.

Nebula is fully open-source under the MIT license. Every component is available for inspection, modification, and self-hosting. You can run a complete Nebula network with zero dependency on us.

OpenVPN Community Edition is open-source under the GPLv2 license. However, the commercial products (Access Server, CloudConti) are proprietary. Many of the management and enterprise features are only available in the paid versions.

Managed Nebula offers simple per-host pricing:

• Free: Up to 100 hosts, 2 routes, SSO, and a simple management UI. No credit card required.
• Pro: $1/host/month with unlimited hosts, up to 100 routes, priority support, and guaranteed uptime
• Enterprise: Custom pricing with a dedicated Slack support channel and network design assistance

See our pricing page for full details, or contact sales for Enterprise.

OpenVPN Community Edition is free but self-managed. Access Server pricing is per concurrent connection, with a free tier for 2 connections. CloudConti is priced per connection per month.

Choose Managed Nebula if you want:

• Direct host-to-host connectivity with no central bottleneck
• A mesh network that scales without adding server capacity
• No single point of failure in your network’s data plane
• Built-in, group-based firewall rules on every host
• Modern cryptography with low overhead
• Simple per-host pricing with a generous free tier

Choose OpenVPN if you want:

• A traditional hub-and-spoke VPN with a single gateway
• Broad client compatibility across legacy platforms
• A well-established solution with decades of deployment history
• Centralized traffic inspection at the VPN server