Hi, I’m using OpenBSD as a router with a Greek ISP called “Cosmote” that is routes traffic through MAP-E[^1]. The main reason I use OpenBSD as a router is the “batteries-included” design. Everything I need can be found on the base system. Unfortunately, MAP-E CE is not supported natively by OpenBSD. Looking that current state, to get full MAP-E support in there are three things that need to get done:
1. PF MAP-E source-port NAT: there is a FreeBSD derived working patch sent to the tech mailing in 2021 with the respective source code available on GitHub[^3] under the OpenBSD compatible ISC License. 2. DHCPv6 Softwire46 / MAP-E provisioning: Current dhcp6leased (dhcp6leased.h) handles standard options, but not options codes 89-96 required for this operation. 3. Lease-to-interface orchestration: Something needs to react when the delegated prefix or MAP rule changes, extract data to populate the `gif0` interface I have a working implementation right now, using a patch submitted to the “tech" mailing list in 2021[^2]. I’m using static data extracted from the router via tcpdump pcap for (2) and for (3) I’m using a perl-based script. I’m testing the setup right now, the MTU had to be modified twice to properly load some websites. Is anyone working on this by chance? Kind regards, PA [^1]: MAP-E is an IPv4-over-IPv6 transition mechanism defined in RFC 7597. It provides stateless, algorithmic mapping between IPv6 prefixes and IPv4 address/port information. In shared-IPv4 deployments, customers are assigned distinct port sets, identified by a PSID, allowing multiple CEs to share the same IPv4 address. Because the CE or BR can derive the correct MAP IPv6 endpoint from the IPv4 address and port using mapping rules, the BR does not need to maintain per-flow port-binding state, which improves scalability. MAP-E can also support direct CE-to-CE forwarding in mesh mode when Forwarding Mapping Rules are configured. [^2]: "pf NAT source port translation of MAP-E Customer Edge (RFC 7597)”, Toru Mano, 202, link: https://marc.info/?l=openbsd-tech&m=163198247009258&w=2 [^3]: https://github.com/toru-mano/openbsd-pf-map-e-ce
