Re: [Pengfork-devel] Improvements

[Jean-Charles Salzeber]

On Thu, Aug 22, 2002 at 11:12, Nicolas Burrus wrote:
> On Thursday 22 August 2002 00:51, Jean-Charles Salzeber wrote:
> > I've thinked about some possibility for the IP interface:
> >   * As in previous version, use tun interface:
> >        + Very easy to implement
> >        + This choice is logic, AOL use a tunneling protocol
> >        - Only portable on Linux/*BSD/Solaris(2.6,7.0,8.0)
> >        ...
> 
> - It seems a little slower than the ppp interface (just for me ?).
> 
> I think it's a good choice to begin.

It should be the more efficient network interface because it accept
raw IP packet without manipulation.
I don't use it for the current version of peng, if it is slow, I don't
know the reason perhaps there is a bottleneck somewhere in the code,
perhaps the kernel implementation is not really efficient...
In all case, this could not be significant enough to slow down the
connection on a 56K modem (maybe not for high-speed connection like
cable)

> >   * use BPF on any interface:
> >        + We could use any existing interface
> >        + Would work on several systems
> >        - It is a bit tricky
> >        ...
> 
> I don't know well how it works.

humm... the idea is to send raw IP packet on any network interface, and
use BPF to capture packet directed to AOL on this interface.
BPF(Berkeley/BSD Packet Fileter) is mainly used in tcpdump and other
low-level network tools.

> 
> >   * Completly re-encapsulating IP under ppp and launch pppd:
> >        + we could use existing code & program (pppd)
> >        + Would be extremly portable
> >        - Need much work to implement (I think...?)
> >        - would be more CPU intensive
> >        ...
> 
> I don't see how this can works, where do you want to reencapsulate IP under 
> ppp ? I thought this could be made at kernel level only.

well, I'm not a PPP guru, I don't know if what I said make sense.
I'm thinking of something like this:

AOL<->Modem<->Peng<->translator aol/ppp<->fifo/socket<->pppd
               |                                         ^
               |          launch                         |
               \-----------------------------------------/

After this the user see a normal ppp connection, and we would not have
to handle network interface.
Some of the translating work could be done in user or kernel mode.
But for example for the IP stack config, we must do this in user mode.

> > I've also heard that the last AOL protocol (version 7.0) is a modified
> > PPP, so here we could make a patch to pppd and use it. It would be nice!
> 
> I don't know which part of the ppp stuff is done by the kernel and which part 
> by pppd, but I'm not sure a patch to pppd would be enough in this case.

I can't say more... I do not have enough information.

> BTW: is there only french people concerned by pengaol ?

I know Peng work on US & Germany
But I don't know if there are international people interested in
helping.

> 
> -- 
> Nicolas Burrus

JC

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