Re: 240/4

[Vince Fuller <vaf () cisco com>]

On Thu, Oct 18, 2007 at 11:00:42PM +0100, michael.dillon () bt com wrote:
> > why on earth would you want to go and hack this stuff together,  
> > knowing that it WILL NEVER WORK
>
> Because I have read reports from people whose technical expertise I
> trust. They modified the TCP/IP code of Linux and FreeBSD and were able
> to freely use 240/4 address space to communicate between machines. This
> means that IT WILL WORK.
>
> The reports stated that the code patch was simple because it involved
> simply removing a line of code that disallowed 240/4 addresses.

Actually, to do the job right, you have to change a handful of conditionals
in about five different files in the Linxux kernel: in.h (really just
cleanup to remove unused macros), devinet.c, fib_frontend.c, ipconfig.c,
and route.c.

Attached are the diffs for a 2.6 kernel (implemented and tested on an Ubuntu
7.04 system) and for a 2.4 kernel (implemented and tested on a Linksys
WRT45GL running OpenWRT whiterussian 0.9).

As mentioned in an earlier message, Mac OSX, at least the version that came
with a Powerbook G4 that I have, will accept a 240/4 address without any
modifications - I used it to test the Linux patches. There does appear to be
a one line change needed to FreeBSD and/or OSX for it to act as a router.

Have fun.

        --Vince

Attachment: diff-2.6
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Attachment: diff-2.4
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