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From: Andrew Lunn <andrew@lunn.ch>
To: The list for a Better Approach To Mobile Ad-hoc Networking
	<b.a.t.m.a.n@lists.open-mesh.org>
Subject: Re: [B.A.T.M.A.N.] [PATCH 3/8] batman-adv: randomize initial seqno to avoid collision
Date: Tue, 7 Feb 2012 13:46:20 +0100	[thread overview]
Message-ID: <20120207124620.GB15165@lunn.ch> (raw)
In-Reply-To: <201202072021.55937.lindner_marek@yahoo.de>

On Tue, Feb 07, 2012 at 08:21:55PM +0800, Marek Lindner wrote:
> On Tuesday, February 07, 2012 20:12:00 Andrew Lunn wrote:
> > Does this sequence number have any security relevance? Does it make
> > sense to use the TCP sequence number generation code?
> 
> There is no security relevance I know of. The idea was simply to start with 
> random number. Random is a bit better than 1.  ;-)
> 
> Where can I find the TCP sequence number code you are referring to ?

I had to go find it, since i've never looked at it before.

net/core/secure_seq.c:

__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
                                 __be16 sport, __be16 dport)

but it does not look very re-usable, since it takes all these
addresses. What might be usable is:

__u32 secure_ip_id(__be32 daddr)
{
        u32 hash[MD5_DIGEST_WORDS];

        hash[0] = (__force __u32) daddr;
        hash[1] = net_secret[13];
        hash[2] = net_secret[14];
        hash[3] = net_secret[15];

        md5_transform(hash, net_secret);

        return hash[0];
}

passing it the last four bytes of the originator MAC address?

	Andrew

  reply	other threads:[~2012-02-07 12:46 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-07  9:19 [B.A.T.M.A.N.] B.A.T.M.A.N. V - the next steps Marek Lindner
2012-02-07  9:19 ` [B.A.T.M.A.N.] [PATCH 1/8] batman-adv: move ogm initialization into the proper function Marek Lindner
2012-02-12 14:57   ` Marek Lindner
2012-02-07  9:20 ` [B.A.T.M.A.N.] [PATCH 2/8] batman-adv: refactoring API: find generalized name for bat_ogm_init callback Marek Lindner
2012-02-07  9:20   ` [B.A.T.M.A.N.] [PATCH 3/8] batman-adv: randomize initial seqno to avoid collision Marek Lindner
2012-02-07  9:33     ` Martin Hundebøll
2012-02-07 11:10       ` Marek Lindner
2012-02-07 11:13         ` Martin Hundebøll
2012-02-07 11:50           ` Marek Lindner
2012-02-07 12:12     ` Andrew Lunn
2012-02-07 12:21       ` Marek Lindner
2012-02-07 12:46         ` Andrew Lunn [this message]
2012-02-12 15:01     ` Marek Lindner
2012-02-07  9:20   ` [B.A.T.M.A.N.] [PATCH 4/8] batman-adv: add iface_disable() callback to routing API Marek Lindner
2012-02-12 15:02     ` Marek Lindner
2012-02-07  9:20   ` [B.A.T.M.A.N.] [PATCH 5/8] batman-adv: handle routing code initialization properly Marek Lindner
2012-02-12 15:04     ` Marek Lindner
2012-02-07  9:20   ` [B.A.T.M.A.N.] [PATCH 6/8] batman-adv: refactoring API: find generalized name for bat_ogm_init_primary callback Marek Lindner
2012-02-12 15:08     ` Marek Lindner
2012-02-07  9:20   ` [B.A.T.M.A.N.] [PATCH 7/8] batman-adv: rename BATMAN_OGM_LEN to BATMAN_OGM_HLEN Marek Lindner
2012-02-12 15:09     ` Marek Lindner
2012-02-07  9:20   ` [B.A.T.M.A.N.] [PATCH 8/8] batman-adv: mark existing ogm variables as batman iv Marek Lindner
2012-02-12 15:11     ` Marek Lindner
2012-02-12 14:58   ` [B.A.T.M.A.N.] [PATCH 2/8] batman-adv: refactoring API: find generalized name for bat_ogm_init callback Marek Lindner

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