ng_ip_input use case

[Brooks Davis]

On Thu, Oct 02, 2003 at 04:09:50PM -0700, Julian Elischer wrote:
> 
> 
> On Thu, 2 Oct 2003, Brooks Davis wrote:
> 
> > On Thu, Oct 02, 2003 at 03:45:47PM -0700, Julian Elischer wrote:
> > > On Thu, 2 Oct 2003, Vincent Jardin wrote:
> > > 
> > > > I read the man of ng_ip_input and the source code. However I do not
> > > > understand what the use cases could be. Who is using it and what's
> > > > for ?
> > >
> > > I have no idea what it is used for.. similar effect can be made by
> > > using the ng_iface node, but I think that they didn't want a separate
> > > interface for each packet source..
> > >
> > > I suggest we ask brooks..(cc'd).  I could imagine it somehow connected
> > > with the 300 processor FreeBSD based cluster that he is working on at
> > > hos job (especially as it has their copyright).
> > 
> > It was for a network emulator we were trying to build to allow us to
> > run real, unmodified programs in an environment where each program
> > was assumed to be an independent agent and the communication topology
> > between agents changed in realtime.  Each agent was to bind to the IP
> > address of an IP-over-IP tunnel (gif on the FreeBSD end).  We would then
> > take the packets, mangle them slightly and send them off to the emulator
> > (I think part of the goal was to let us use more or less off the shelf
> > emulation gear in the middle without needing a workstation for each
> > agent).  When we got them back, we'd remanged them and stuff them back
> > into the IP stack with ng_ip_input so it could decide which gif tunnel
> > to send it back down.  The emulation part of the project died when our
> > funding for it dried up so we've not actually using this module for
> > anything.
> 
> was there a reason to not use the ng_iface node?
> (packets enterred on the INET hook if an iface node will be injected
> into the ip stack) (from memory)

Probably not.  I didn't know netgraph all that well at the time so it
wouldn't suprise me if I reinvented a wheel or two.

-- Brooks

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