udp fragmentation

[Max Laier]

On Monday 04 June 2007, Max Laier wrote:
> Hi again,
>
> On Monday 04 June 2007, Hugo Koji Kobayashi wrote:
> > pf is running on the DNS client machine. The DNS server is on a
> > completely different network (I don't control this server). The
> > client can send the udp request with no problem (it's a small udp
> > datagram; less than 512 bytes), the server sends the udp response
> > fragmented, but the client can't receive it.
> >
> > Please, find attached a new test with the requested information.
> >
> > udp:
> >         36 datagrams received
> >         2 with bad checksum
> >         34 delivered
> >         40 datagrams output
>
> <test>
>
> > udp:
> >         36 datagrams received
> >         3 with bad checksum
> >         33 delivered
> >         41 datagrams output
>
> Aha!  Can you confirm that "bad checksum" increases for every
> fragmented packet and I'll look for a cure.

I can't reproduce this.  What hardware are you running on?  (arch, nic 
(rx/txcsum), non-standart CFLAGS).  Just to confirm I'm testing the right 
cases, my setup looks like:

Host1       Host2      Host3

netsend -> pf scrub -> pf scrub -> netreceive

Everthing works as expected with various UDP payloads > MTU.

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