feature wish: extend Linux VRF support to other OSes

[Gert Döring]

This is more a long-term thing...

• collect information how "multiple routing tables", "VRF", etc. are done on various OSes
• see if we can implement this in a sufficiently generic way

What I've found so far:

• Linux: SO_BINDTODEV will put the socket into "a VRF" if you bind to the (named) "VRF device" (-> vrf blue -> bind-dev blue). An interface is put into a VRF by enslaving it under the VRF master device.

• FreeBSD: boot with "net.fibs=N" (default is 1, boot-time only), then a process can be put into a non-default fib with setfib <i> openvpn... or setfib(2) or setsockopt(SO_SETFIB). An interface is put into a fib with ifconfig ... -fib <i>

• OpenBSD: route has -T table arguments to specifiy the routing table to use. route -T table exec $command seems to be similar to FreeBSD's setfib i $command. ifconfig has rdomain $rdomainid to specify a "routing domain". setsockopt() has SO_RTABLE "set the routing table used for route lookups", and setrtable(2) can be used to set the whole process's default table. (see man route, ifconfig, netintro, setsockopt)

• NetBSD: ???

• MacOS: ???

• Windows: ???

[tct]

Looks interesting - CC'd