MacOS X vmnet NAT networking
MacOS X 10.10 (Yosemite) introduced the somewhat undocumented vmnet
framework. This exposes virtual network interfaces to userland applications.
There are a number of advantages of this over previous implementations:
- Unlike tuntaposx, this is builtin to MacOS X now and so is easier to package up and distribute for end users.
vmnetuses the XPC sandboxing interfaces and should make it easier to drop a hard dependency on running networking applications asroot.- Most significantly,
vmnetoptionally supports NATing network traffic to the outside world, which was previously unsupported.
These OCaml bindings are constructed against the documentation contained
in the <vmnet.h> header file in Yosemite, and may not be correct due to
the lack of any other example code. However, they do suffice to run
MirageOS applications that can connect to the
outside world.
Note the application must be configured to use DHCP: static IPs are not supported. To configure a MirageOS application use a command like:
mirage configure -t macosx --dhcp true
The bindings are also slightly complicated by the need to interface GCD thread pools with the OCaml runtime, so please report any instabilities that you see when using this interface as a consumer.
There are two libraries provided:
Vmnetis the raw OCaml binding to thevmnetframework, using OCaml preemptive threads to handle synchronisation.Lwt_vmnetuses the Lwt framework to provide a monadic asynchronous I/O interface at a higher level.
Most users should use Lwt_vmnet to handle guest traffic.