Re: [PATCH] tcp: Generalized TTL Security Mechanism

On Thu, Jan 14, 2010 at 03:04:54AM -0800, David Miller wrote:

From: Andi Kleen <andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org>
Date: Thu, 14 Jan 2010 11:58:13 +0100

quoted

Stephen Hemminger [off-list ref] writes:

quoted

Only TCP is supported, but could also be added to UDP, DCCP, SCTP
if desired.

Perhaps I'm blind, but where is the default set if the socket
option is not used? 

Socket allocation memset()'s it to zero.

Yes, but there's no special case for zero in the check path?

It's just

+       if (iph->ttl < inet_sk(sk)->min_ttl)
+               goto discard_and_relse;

I'm probably missing something, but naively I would expect all 
packets with ttl > 0 to be discarded then when min_ttl is zero.

-Andi
-- 
ak-VuQAYsv1563Yd54FQh9/CA@public.gmane.org -- Speaking for myself only.