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From: Aviad Lahav <aviad.lahav@gmail.com>
To: netfilter@vger.kernel.org
Subject: Netfilter injects network headers?
Date: Mon, 7 Dec 2009 21:05:41 +0200	[thread overview]
Message-ID: <85ce6a220912071105s7706f877k9547362aefd76056@mail.gmail.com> (raw)

Hi all,
I'm trying to set up an SSL transparent proxy, and I've seen very
bizarre behavior on my system.
I've added two NAT rules to  the PREROUTING chain, looking like this:

# iptables -L -v -t nat
Chain PREROUTING (policy ACCEPT 561 packets, 70236 bytes)
 pkts bytes target     prot opt in     out     source               destination
   20  1280 REDIRECT   tcp  --  ppp0   any     anywhere
anywhere            tcp dpt:4309 redir ports 4443
    8   512 REDIRECT   tcp  --  ppp0   any     anywhere
anywhere            tcp dpt:https redir ports 4443

So I've got a listener on port 4443, accepting connections from both
ports 443 and 4309.
When I'm doing the first recv() in my accepting server, I get the
incoming connections to port 443 very well, BUT:
Incoming connections to port 4309 gets *3 extra bytes* in the
beginning of the connection (maybe also to subsequent packets, but I
haven't had the chance to see this data yet...()

The first 3 bytes I'm getting is:
0x00 0x01 0x05

My machine is an up-to-date Ubuntu 9.10 (karmic), and the packets are
coming from a client connected thru pptpd.
Anyone has a clue?

                 reply	other threads:[~2009-12-07 19:05 UTC|newest]

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