[Openswan Users] Some questions about x.509 certificate authenticate

孙国辉(VPN技术部) sun_guohui at topsec.com.cn
Wed Apr 11 23:40:50 EDT 2007

----- Original Message ----- 
From: "Paul Wouters" <paul at xelerance.com>
To: "孙国辉(VPN技术部)" <sun_guohui at topsec.com.cn>
Cc: <users at openswan.org>
Sent: Wednesday, April 11, 2007 10:26 PM
Subject: Re: [Openswan Users] Some questions about x.509 certificate authenticate

> On Mon, 9 Apr 2007, Ëï¹ú»Ô(VPN¼¼Êõ²¿) wrote:
>>       I have two hosts-- and which are connected to a hub. They have openswan2.3.1 installed. I have already setup a tunnel using main mode and aggressive mode with x.509 certificate authentication. Detailed configurations are as follows.
>> conn test
>>  left=
>>  leftcert=9.pem
>>  right=
>>  rightcert=10.pem
>>      I use tcpdump to capture the data packet of IKE phase 1. I find that the two hosts don't exchange each other's certificate whether using main mode or aggressive mode. I mean they just exchange each other's the RDN sequence which is part of the x.509 certificate.
> That's because you loaded the certificates explicitely. You should only
> specify the local cert in leftcert= (or rightcert=) and not the remote cert.
Thanks Paul.
                It works as what you said under main mode. But, I still have a question. We know there are six packets during IKE phase 1 negotiation if using main mode.I have all these six packets captured. I find that the right(responder) will send an cert request payload in the fourth packet to the left(initiator). Because the following two packets are encrypted, so I guess the initiator will send its cert in the fifth packet and the responder will send its cert in the six packet which is the last packet in phase 1. Therefore, both two sides do not need to store its counterpart's cert. Does what I think right???
                But, it doesn't work under aggressive mode if I do not specify the cert file of the right(the responder). It works if I specify the cert file of the right(the responder). I think this is reasonable.I capture all the three packets during IKE pahse 1 negoitiation if using aggressive mode and specifying the right's cert file.
I find that the left(initiator) will send a ID payload to in the first packet to the right(responder). Then, in the second packet the right(responder) send its ID payload to the left(initiator). There is no cert request payload.The third packet is encrypted,so........... Now, I can make sure that cert will not be sent in the first two packets
 and the two sides can not exchang each other's cert in ONE packet--the last encrypted packet. I doubt that the two sides do not really exchang their cert during phase 1. They only exchange each other's RDN sequence. So the left must store the right's cert in local if using aggressive mode. Does what I think right? And do you know how openswan's aggressive mode really works when using cert?
            Sorry for my poor English  (*_*) and waiting for your reply! 
>> 3. For question 2, I want the openswan to store its own certificate only and get its counterparts' publick keys through IKE phase 1 negotiation. Therefore, it will save a lot storage space. Does this method work?
> Yes.
> Paul
> -- 
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