Re: Bad IP-checksums

[Fyodor <fyodor () insecure org>]

On Fri, Aug 15, 2008 at 03:11:02PM +0200, Gisle Vanem wrote:
> After some digging, I found two places where 'ip->ip_sum'
> wasn't cleared before calculating the sum. I believe the omission
> in osscan2.cc that was causing me trouble. A patch against today's
> svn:

Did this actually fix the problem for you?  For osscan2.cc, it looks
at first glance like ip_sum should already be zero because of line
3064:

    memset((char *) packet, 0, sizeof(struct ip) + sizeof(struct udp_hdr));

Your tcpip.cc change looks like it only relates to fragmented packets.
I'm not sure if resetting ip_sum to 0 is needed there, but I'll
probably add it because it is easy and shouldn't hurt anything.

Cheers,
-F

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