Hello,
Thanks for your answer!
You are right, the initial CHILD_SA is negociated during the IKE_AUTH exchange.
I do see a rekey of the CHILD_SA, and there is indeed a PFS included.
However, there is a questionable situation in the case the initiator and the
responder sides do not share the same 'esp' PFS group (I set the initiator's
lifetime to 3m for testing purposes)
- The first CHILD_SA is created on both sides using IKE_AUTH.
- When the rekey occurs, the responder tells the initiator that no suitable
proposal has been chosen. Furthermore the responder keeps the current IKE and
CHILD SAs.
- The initiator then shows a 'rekeing active' status but its SA ends up killed
by the kernel.
- The initiator has to wait for the IKE SA rekey to get the CHILD SA up again.
initiator side:
#ipsec statusall
...
Security Associations (1 up, 0 connecting):
net-net[1]: ESTABLISHED 10 minutes ago,
172.18.0.54[[email protected]]...172.18.0.53[[email protected]]
net-net[1]: IKEv2 SPIs: 86e385832aae080f_i* acbcfbb47881a7be_r, public key
reauthentication in 5 hours
net-net[1]: IKE proposal: AES_CBC_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_2048
net-net{1}: INSTALLED, TUNNEL, ESP SPIs: c4e02848_i c2c6dec8_o
net-net{1}: AES_CBC_128/HMAC_SHA1_96, 0 bytes_i, 0 bytes_o, rekeying
active
net-net{1}: 172.54.0.0/16 === 172.53.0.0/16
#setkey -D
No SAD entries.
Regards,
Emeric
----- Mail original -----
De: "Thomas Egerer" <[email protected]>
À: [email protected]
Cc: "emeric poupon" <[email protected]>
Envoyé: Vendredi 1 Août 2014 22:14:02
Objet: Re: [strongSwan] CHILD SA and PFS
Hi Emeric
On 08/01/2014 04:05 PM, Emeric POUPON wrote:
> Hello,
>
> I have some problems enabling PFS on the CHILD SA.
> I'm using strongswan 5.2.0 on FreeBSD.
>
> Here are the site configurations:
looks good.
However [1], the IKE_AUTH exchange responsible for
establishing the *first* CHILD_SA does not include a key exchange
(KE), whereas [2], the CREATE_CHILD_SA exchange responsible
for creating (subsequent), or rekeying children, does include
an (optional) key exchange ([KE]).
If you wait for the configured keylife of <=60 minutes, you
should see a rekeying of the CHILD_SA take place, including
the configured PFS-group.
Cheers,
Thomas
[1] http://tools.ietf.org/html/rfc5996#appendix-C.2
[2] http://tools.ietf.org/html/rfc5996#appendix-C.4
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