[strongSwan] cannot use strict mode when right=%any

[Simon Chan]

Hi Tobias,

Thank you so much for your quick response. It is good to know that there is a reason for charon to
know about IKEv1 connections. But the problem I am facing is not over yet.


Apparently root cause of my mistaken identity problem is "right=%any". Ordering ikev2 tunnels ahead of
ikev1 helped only because there are  2 conns in ipsec.conf. Get rid of pluto conn leave behind only 1 conn 

so there is no chance for confusion. Normally I have 1000 tunnels and they are all"right=%any". 

I get the NO_PROPOSAL_CHOSEN problem easily with two IKEv2 conns that have different
cipher suites. E.g. first one use sha1 and second one use md5:


conn first
   left=192.168.3.193
   right=%any
   rightid=@1000-1
   ike=aes128-sha1-modp1536!
   keyexchange=ikev2

   ...

conn second

   left=192.168.3.193
   right=%any
   rightid=@1000-2
   ike=aes128-md5-modp1536!
   keyexchange=ikev2
   ...

Here is the syslog:
charon: 11[NET] received packet: from 192.168.3.195[500] to 192.168.3.193[500]
charon: 11[ENC] parsed IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) ]
charon: 11[CFG] looking for an ike config for 192.168.3.193...192.168.3.195
charon: 11[CFG]   candidate: 192.168.3.193...%any, prio 5
charon: 11[CFG]   candidate: 192.168.3.193...%any, prio 5
charon: 11[CFG] found matching ike config: 192.168.3.193...%any with prio 5
charon: 11[IKE] 192.168.3.195 is initiating an IKE_SA
charon: 11[IKE] IKE_SA (unnamed)[3] state change: CREATED => CONNECTING
charon: 01[JOB] next event in 29s 999ms, waiting
charon: 11[CFG] selecting proposal:
charon: 11[CFG]   no acceptable INTEGRITY_ALGORITHM found 
charon: 11[CFG] received proposals: IKE:AES_CBC_128/HMAC_MD5_96/PRF_HMAC_MD5/MODP_1536
charon: 11[CFG] configured proposals: IKE:AES_CBC_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1536
charon: 11[LIB] size of DH secret exponent: 1534 bits
charon: 11[IKE] received proposals inacceptable
charon: 11[ENC] generating IKE_SA_INIT response 0 [ N(NO_PROP) ] 

From the syslog, it would seem once a possible candidate is picked (by their order in ipsec.conf), the proposal
selection would not look at the other conns that are also 192.168.3.193...%any. Is this true?
If true, any suggestion how I can get tunnels with different ciphers co-exist?  Ideally modify the code to go back and pick another <my_ip>...%any candiate is best for my application. Or perhaps I ban strict mode when right=%any?

Thank you again for your help.
Simon


________________________________
 From: Tobias Brunner <tobias at strongswan.org>
To: Simon Chan <simon.chan3 at yahoo.ca> 
Cc: "users at lists.strongswan.org" <users at lists.strongswan.org> 
Sent: Wednesday, February 8, 2012 2:35:33 AM
Subject: Re: [strongSwan] NO_PROPOSAL_CHOSEN error when IKEv1 and IKEv2 has closely resemble but not exact suites
 
Hi Simon,

> Is it possible that charon is searching for matches from pluto's
> connections?  Why should charon have knowledge of
> pluto's connections?

Yes, that's exactly what's happening here.  By default, charon loads all
connections whether they have keyexchange set to ikev2 or not.  But it
uses IKEv1 connections only as responder (the reason for this was
probably to simplify configuration on gateways, as only one config would
be necessary).  If you don't want this you could apply the attached patch.

> In another attempt to debug the problem, we arranged the order of the
> tunnels in ipsec.conf so that IKEv2 conn is ahead of the IKEv1 conn.
> Then connection is established. And the IKEv1 which is now second in
> /etc/ipsec.conf still works.

Yep, that works too, as charon simply uses the first matching connection.

Regards,
Tobias
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