12 | 12 | * if the system is set to autoconfigure IPv6 addresses (ip6mode=autohost in /etc/rc.conf), and there are IPv6 router advertisements coming in on the normal LAN interface, OpenVPN TAP mode + IPv6 will not work. The reason behind this is that the NetBSD kernel enforces the "an IPv6 autoconfiguring host must only have one single IPv6 interface" rule (technical: the "connected/cloning" route (UC) for the IPv6 /64 configured on the TAP interface is removed by the kernel upon reception of a RA on the LAN interface, and subsequently neighbor discovery on the TAP interface fails). Using "tun" mode works, because this kernel behaviour only seems to apply to interfaces that do neighbor discovery (ND), which tun ifs don't do. Workaround: set "ip6mode=host" and statically configure your LAN IPv6 address + routers, or use --dev tun. (This applies to NetBSD at least up to 5.1) |