The selection is not based on "best", but rather on the order of
algorithms at the initiator side first and the responder side second.
AFAIK, strongSwan accepts the first proposed algorithm that is also
configured configured locally. The first algorithm proposed by windows
and also accepted at your server is
Windows: "IKE:AES_GCM_16_128/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024"
strongSwan: proposals =
aes256gcm16-aes128gcm16-sha384-sha256-prfsha384-prfsha256-modp1024
If you want the better algorithm, then move it first in your windows
configuration, or change strongSwan to only accept the algorithms you
prefer, i.e drop "-aes128gcm16"
proposals = aes256gcm16-sha384-sha256-prfsha384-prfsha256-modp1024
Regards,
Jafar
On 5/1/2018 4:59 PM, Christian Salway wrote:
*version: strongSwan 5.6.2*
When I connect from Windows 10, strongSwan replies with a different
policy than requested, causing a policy mismatch
```
connections {
default {
version = 2
send_cert = always
encap = yes
pools = pool1
unique = replace
proposals =
aes256gcm16-aes128gcm16-sha384-sha256-prfsha384-prfsha256-modp1024
local {
id = vpnserver
certs = vpnserver.crt
}
remote {
auth = eap-mschapv2
eap_id = %any
}
children {
net {
local_ts = 10.0.0.0/20
inactivity = 1h
}
}
}
}
```
When Windows connects, strongSwan gives it the wrong policy and hence
Windows 10 reports a*policy match error*
May 1 21:53:12 08[CFG] *received proposals*:
IKE:3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024,
IKE:3DES_CBC/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024,
IKE:3DES_CBC/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_1024,
IKE:AES_CBC_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024,
IKE:AES_CBC_128/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024,
IKE:AES_CBC_128/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_1024,
IKE:AES_CBC_192/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024,
IKE:AES_CBC_192/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024,
IKE:AES_CBC_192/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_1024,
IKE:AES_CBC_256/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024,
IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024,
IKE:AES_CBC_256/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_1024,
IKE:AES_GCM_16_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024,
IKE:AES_GCM_16_128/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024,
IKE:AES_GCM_16_128/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_1024,
IKE:AES_GCM_16_256/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024,
IKE:AES_GCM_16_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024,
IKE:AES_GCM_16_256/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_1024
May 1 21:53:12 08[CFG] *configured proposals*:
IKE:AES_GCM_16_256/AES_GCM_16_128/PRF_HMAC_SHA2_384/PRF_HMAC_SHA2_256/MODP_1024
May 1 21:53:12 08[CFG] selected proposal:
IKE:*AES_GCM_16_128/PRF_HMAC_SHA2_256/MODP_1024*
Expected response (I'm guessing)
*AES_GCM_16_128/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024
*(although I dont know why it doesnt chose the better ciphers).
