Security Model

mqproxy uses a trusted proxy model: mqproxy-client, mqproxy-server, and the MPQUIC connection between them are trusted. In TCP Proxy Mode and Transparent Capture mode (without --mitm), application↔origin TLS is preserved end-to-end (mqproxy never sees plaintext — it relays raw TLS bytes opaquely). Applications with certificate pinning continue to work.

The HTTP Request Execution Gateway is an explicit delegation model — the client delegates HTTP request execution to a trusted gateway that establishes (and always verifies) the origin TLS — not a transparent MITM. Gateway requests are authenticated individually (X-Mq-Auth, per-request); Authorization is reserved for the origin and forwarded, while Cookie and X-Mq-* never leave the gateway.

TLS MITM ingress

TLS MITM ingress (--mitm, opt-in) is an operator-controlled / consenting-endpoint model for managed devices where the operator's CA is installed locally — a corporate-proxy or personal-VPN posture, not a transparent attack on third parties. The client forges per-host leaves from that CA, terminates the browser's TLS as HTTP/2, and maps each request onto the Gateway tunnel.

Its trust assumptions:

• The CA private key is the anchor (loaded with O_NOFOLLOW/O_CLOEXEC, refused if encrypted or group/world-readable).
• Browser-supplied X-Mq-* headers are always stripped (never interpreted as controls — the client injects its own x-mq-auth).
• Vendored-BoringSSL symbols are isolated from libcurl's system OpenSSL.
• The feature is fail-closed (misconfiguration is a startup error, never silent passthrough, with a bounded ClientHello drain and H2 resource limits).

Cert-pinned hosts can be excluded with --ignore-host(s), which splices them opaquely so the origin's real certificate reaches the client. See the TLS MITM guide for the operational details.

License

Apache-2.0. See LICENSE.

Acknowledgments

• XQUIC (Alibaba) — the QUIC/MPQUIC transport, via the mp0rta fork.
• BoringSSL — TLS backend.