From: David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
To: andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org
Cc: shemminger-ZtmgI6mnKB3QT0dZR+AlfA@public.gmane.org,
netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] tcp: Generalized TTL Security Mechanism
Date: Thu, 14 Jan 2010 03:27:39 -0800 (PST) [thread overview]
Message-ID: <20100114.032739.217960336.davem@davemloft.net> (raw)
In-Reply-To: <20100114112216.GK12241-u0/ZJuX+froe6aEkudXLsA@public.gmane.org>
From: Andi Kleen <andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org>
Date: Thu, 14 Jan 2010 12:22:16 +0100
> 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, the feature works from top to bottom.
The idea is that the min_ttl is set very high, so that
you'll only accept packets from hosts that started with
a ttl of 255 and are within a hop or two from you. (therefore
you'd set min_ttl to 254 or 253, something like that)
Since the ttl can never be less than zero, the test
will never hit when min_ttl is zero, and thus this is
that state where the socket option is not enabled.
next prev parent reply other threads:[~2010-01-14 11:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-11 6:00 [PATCH] tcp: Generalized TTL Security Mechanism Stephen Hemminger
2010-01-11 11:25 ` Eric Dumazet
[not found] ` <4B4B0AA3.6010207-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2010-01-11 16:25 ` Stephen Hemminger
2010-01-11 17:04 ` Eric Dumazet
2010-01-11 17:10 ` Eric Dumazet
[not found] ` <4B4B5B84.3090409-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2010-01-12 0:27 ` David Miller
2010-01-12 0:28 ` David Miller
2010-01-14 10:58 ` Andi Kleen
[not found] ` <873a29eywq.fsf-3rXA9MLqAseW/qJFnhkgxti2O/JbrIOy@public.gmane.org>
2010-01-14 11:04 ` David Miller
[not found] ` <20100114.030454.16178889.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2010-01-14 11:22 ` Andi Kleen
[not found] ` <20100114112216.GK12241-u0/ZJuX+froe6aEkudXLsA@public.gmane.org>
2010-01-14 11:27 ` David Miller [this message]
2010-01-14 12:38 ` William Allen Simpson
[not found] ` <4B4F1044.8080500-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2010-01-14 13:14 ` Eric Dumazet
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