netgraph(4) divert(4) to UDP Tunnel

[Ruslan Ermilov]

On Thu, Nov 13, 2003 at 12:24:35PM -0800, Crist J. Clark wrote:
> I'm trying to play around with netgraph(4) for the first time and
> there seem to be some aspects of it that haven't "clicked" in my head
> just yet.
> 
> What I want to do seems like it should be pretty easy. I want to
> send some packets through a UDP tunnel. There is an
> /usr/share/examples/netgraph/udp.tunnel file that is close to what I
> want, but not quite. I want to send packets that have been divert(4)ed
> to the tunnel.
> 
> I can make my two ng_ksocket(8) nodes via the ngctl(8) interface,
> 
>  + mkpeer ksocket d0 inet/dgram/udp
>  + name d0 udptun
>  + msg d0 bind inet/192.168.64.70:10000
>  + msg d0 connect inet/192.168.64.50:10000
>  + mkpeer ksocket d1 inet/raw/divert
>  + name d1 divtun
>  + msg d1 bind inet/0.0.0.0:8668
> 
> But how do I then connect the two of them up? I assume that I use
> 'connect' within ngctl(8), but I haven't figured out what the
> arguments need to be with the documentation and examples I've found.
> 
> The other thing I suspect I should be doing, is actually running the
> 'mkpeer' through the first node I create in ngctl(8), but I can't seem
> to get that to work,
> 
>  + mkpeer ksocket d0 inet/dgram/udp
>  + name d0 udptun
>  + msg d0 bind inet/192.168.64.70:10000
>  + msg d0 connect inet/192.168.64.50:10000
>  + mkpeer d0 ksocket d1 inet/raw/divert
>  ngctl: send msg: Socket is already connected
> 
> I think it is actually complaining about the hook between my ngctl
> node and the udptun node and not the creation of the divert socket?
> 
> Basically, I think my conceptual problem is with the fact that you
> start with the ngctl(8) node in the middle of everything. How do I
> create my new nodes and get the ngctl(8) node out of the middle?
> 
I don't think this is currently possible (I'd like to be mistaken).
The main difference between ng_iface (from the classical tunnel
example) and ng_ksocket is that the first is so-called ``persistent''
node, i.e., when the number of hooks becomes zero, the node does
not get removed automatically.  This same is not true for ksocket.

But I think this could be a work around:

ngctl
+ mkpeer tee dummy left2right
+ name dummy mytee
+ mkpeer mytee: ksocket left inet/dgram/udp
+ name mytee:left udp1
+ mkpeer mytee: ksocket right inet/dgram/udp
+ name mytee:right udp2
+ exit

# ngctl show mytee:
  Name: mytee           Type: tee             ID: 0000000e   Num hooks: 2
  Local hook      Peer name       Peer type    Peer ID         Peer hook
  ----------      ---------       ---------    -------         ---------
  right           udp2            ksocket      00000010        inet/dgram/udp
  left            udp1            ksocket      0000000f        inet/dgram/udp

I've omitted any socket-related ops, and both sockets are of type
UDP (I don't have the divert(4) support compiled in on this machine),
but this should not be important.


Cheers,
-- 
Ruslan Ermilov		Sysadmin and DBA,
ru at sunbay.com		Sunbay Software Ltd,
ru at FreeBSD.org		FreeBSD committer
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