Introducing ipxlat: a stateless IPv4/IPv6 translation device

Summary

From: Ralf Lici <ralf@mandelbit.com> To: netdev@vger.kernel.org Cc: "Daniel Gröber" <dxld@darkboxed.org>, "Ralf Lici" <ralf@mandelbit.com>, "Andrew Lunn" <andrew+netdev@lunn.ch>, "Antonio Quartulli" <antonio@mandelbit.com>, "David S. Miller" <davem@davemloft.net>, "Eric Dumazet" <edumazet@google.com>, "Jakub Kicinski" <kuba@kernel.org>, linux-kernel@vger.kernel.org, "Paolo Abeni" <pabeni@redhat.com> Subject: [RFC net-next 00/15] Introducing ipxlat: a stateless IPv4/IPv6 translation device Date: Thu, 19 Mar 2026 16:12:09 +0100 [thread overview] Message-ID: <20260319151230.655687-1-ralf@mandelbit.com> (raw) Hi all, this RFC series introduces ipxlat, a virtual netdevice for stateless packet translation between IPv6 and IPv4. This stateless IP/ICMP translation (SIIT, RFC 7915) device is a building block ultimately allowing suitably configured Linux systems to cover all IPv6<>IPv4 connectivity scenarios outlined in RFC 6144, "Framework for IPv4/IPv6 Translation". While the packet translation function implemented in ipxlat itself is stateless, building stateful NAT64 translators is easy in combination with a sandwich of simple nft SNAT and MASQUERADE rules. Even SIIT-DC (RFC 7755 / 7756) ER/BR functions including EAMT (RFC 7757) are thought to be possible with suitable nft/iptables configuration, but this needs further testing. The series contains patches covering driver core, translation paths, netlink API, selftests and documentation. See Documentation/networking/ipxlat.rst for more details. == Architecture == ipxlat sits at a boundary between two kernel models. It is exposed as a netdevice, so it has device semantics such as MTU and netdev statistics. However, most of its processing falls within protocol translation logic. The implementation therefore uses netdevice hooks for integration and lifecycle, while translation behavior follows RFC rules and reuses existing IP stack helpers for routing, fragmentation and checksum handling. Feedback on the netdevice integration...