A QUICker SASE client: re-building Proxy Mode (opens in new tab)
Cloudflare rebuilt the Cloudflare One Client’s proxy mode to address performance problems caused by translating TCP traffic into IP packets through WireGuard. The new design uses HTTP/3 and QUIC streams for direct Layer 4 proxying, eliminating the smoltcp translation layer. Internal tests showed download and upload speeds doubling while latency decreased significantly. ## Limitations of the Original Proxy Architecture - Proxy mode exposed a local SOCKS5 or HTTP proxy for broad application compatibility. - WireGuard operates at Layer 3, while proxy traffic arrives as Layer 4 TCP streams. - The Client used the Rust-based `smoltcp` stack to convert TCP streams into IP packets. - Cloudflare’s edge then converted those packets back into TCP streams. - This added overhead, limited access to modern TCP features, and caused sluggish performance for media-heavy websites, large transfers, and video calls. ## Direct Layer 4 Proxying with QUIC - Cloudflare deprecated WireGuard for proxy mode and adopted QUIC-based transport. - HTTP/3’s `CONNECT` method encapsulates proxy traffic directly in QUIC streams rather than breaking it into Layer 3 packets. - The new architecture: - Removes the smoltcp translation layer. - Uses QUIC’s built-in congestion and flow control. - Allows the Client and Cloudflare edge to tune transport parameters for performance. - Testing showed approximately doubled upload and download speeds and substantially reduced latency. ## Use Cases That Benefit - **Third-party VPN coexistence:** Users can combine legacy VPNs for on-premises resources with zero trust web security without imposing as much performance loss. - **Application partitioning:** Specific browser traffic can be routed through Cloudflare Gateway while other operating-system traffic remains on the local network. - **High-bandwidth workloads:** Streaming, large dataset transfers, and other data-intensive applications receive faster proxy connections. - **Developer and CLI workflows:** Tools using the SOCKS5 listener benefit from lower-latency API calls and data transfers. ## Availability and Configuration - The improvement requires Cloudflare One Client version `2025.8.779.0` or later on Windows, macOS, or Linux. - In the Cloudflare One dashboard: - Go to **Teams & Resources > Devices > Device profiles > General profiles**. - Set **Service mode** to **Local proxy mode**. - Set **Device tunnel protocol** to **MASQUE**. - Verify the active protocol with: ```bash warp-cli settings | grep protocol ``` Organizations using proxy mode should upgrade the client and switch to MASQUE to gain the new QUIC-based performance improvements.