Re: kernel networking stack in userspace

[Paul Goyette <paul%whooppee.com@localhost>]

On Sat, 18 Oct 2008, Antti Kantee wrote:

8< snip >8

> On the contrary, option 2 runs the entire kernel networking stack in
> userspace.  This means that it must have raw ethernet access and
> accomplishes this through the use of tap(4) (similar to e.g. qemu).
> Contrasting the other option, this brings:
>
>  * full networking stack in userspace
>  * the interface and routing table must be configured before use
>  * /dev/tap and interface configuration priviledges are required
>
> To configure the interface from your code, you must emulate what
> ifconfig(8) and route(8) do on a normal system.  There is an
> example in src/sys/rump/net/rumptest/rumptest_net.c on how to do
> this.  I'll probably move that stuff to a library lateron.
>
> Currently, tap must be configured manually as tap0.  To do this, execute
> (with appropriate priviledges):
> golem> ifconfig tap0 create
> golem> ifconfig tap0 up

Can we assume that if you want yet another virtual networking domain, 
you create a tap1, tap2, etc.?

> Optionally, if wanting to bridge to a real network, execute:
> golem> ifconfig bridge0 create
> golem> brconfig bridge0 add tap0 add yourrealif0
> golem> brconfig bridge0 up
> (yes, the first command really is ifconfig, not brconfig)

What about _routing_ between domains?  :)

> Apart from that, both options require threading, which can be enabled by
> setting the RUMP_THREADS environment variable to 1.  Then it's just a
> matter of running the application.  If all goes well, running
> rumptest_net should dump out the html on the main page www.NetBSD.org.
>
> Enjoy (if you're into this sort of stuff ;)
>  - antti
>
> pie-in-the-sky: barring interfacing with tap(4), the userspace kernel
> networking stack is likely to be highly portable.  So if you don't like
> networking on $OS, by all means use the NetBSD TCP/IP stack linked
> against your application ;)

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