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<p class=MsoNormal>Hello,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>My question is about the Netkey Hooks in Linux Netfilter (<a
href="http://strongswan.org/docs/LinuxKongress2009-strongswan.pdf">http://strongswan.org/docs/LinuxKongress2009-strongswan.pdf</a>,
ppt 37). I want to understand the data path. Here is my understanding :<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><img border=0 width=347 height=235 id="Image_x0020_34"
src="cid:image001.jpg@01CD4FA6.D8F12460"><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>1 - The host receives an ESP packet that is intended to it on
its interface. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>2 - The input chain accepts this ESP packet that comes into
the network layer.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>3 - The ESP packet is decapsulated according the appropriate
SA. I have no idea about <i>state in/out</i> meaning. I think that <i>policy in/out/forward</i>
refer to the policy module, doesn't it ?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>4 - The decapsulated<span style='color:#1F497D'> </span>packet
appears again on the same interface. In fact w<span style='color:black'>hen a
host receives ESP packets, we noticed that a tcpdump capture shows both ESP
encapsulated and original packets.</span> This is a particularity of the Netkey
stack. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>5 - The packet can pass through the input chain only if it
meets the properties claimed by the policy module, e.g.<o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New";
color:black'>pkts bytes target prot opt
in out
source
destination <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New";
color:black'> 1 148
ACCEPT all -- eth0
*
10.1.0.0/16
192.168.0.100 <b>policy match dir in pol
ipsec reqid 1 proto 50<o:p></o:p></b></span></p>
<p class=MsoNormal><b><o:p> </o:p></b></p>
<p class=MsoNormal>in that example, all trafic from subnet <span
style='color:black'>10.1.0.0/16 is accepted only if it previously used the
appropriate IPSec policy.<o:p></o:p></span></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Please help me and tell me if I am wrong.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Regards,<o:p></o:p></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal>Stéphanie<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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