[strongSwan] Sudden issues with Windows 10 clients

Christian Salway christian.salway at naimuri.com
Wed May 9 02:42:04 CEST 2018


I don’t change the default ESP ciphers, only the IKE ones.  I should probably look into them at some point.


> On 8 May 2018, at 19:55, Houman <houmie at gmail.com> wrote:
> 
> Thank you both Christian and Jafar for the clear proposals.
> 
> So yes, if I wanted to support Windows 10, iOS/OSX and Linux with the stronger set of encryption. Do I set aes256-sha256-prfsha256-modp2048 into ike only?  Or both in ike and esp?
> 
> This part wasn't quite clear to me.
> 
> Yeah, I have already set [NegotiateDH2048_AES256] in Windows 10.  
> 
> Many Thanks,
> Houman
> 
> 
> 
> On 8 May 2018 at 08:40, Christian Salway <christian.salway at naimuri.com <mailto:christian.salway at naimuri.com>> wrote:
> The problem with Windows (10 at least) is that it offers the weakest ciphers first, so you should remove sha1 and 3des.
> 
> The minimum proposals you should have and which are compatible with Windows 10, OSX, IOS and Linux are the following.
> 
> proposals = aes256-sha256-prfsha256-modp2048-modp1024
> 
> Although I would recommend adding the Windows 10 registry key [NegotiateDH2048_AES256] to use strong ciphers and then you can remove MODP1024
> 
> 
>  <http://www.naimuri.com/>
> 
>> On 7 May 2018, at 15:50, Jafar Al-Gharaibeh <jafar at atcorp.com <mailto:jafar at atcorp.com>> wrote:
>> 
>> Houman,
>> 
>>   The Windows client proposals do not match your configured proposals. Your Windows client expect DG group 15 (MODP2048), where as you have:
>> 
>> aes256-3des-sha1-modp1024
>> 
>> change that to:
>> 
>> aes256-3des-sha1-modp2048
>> 
>> I'd also add sha256 at least before sha1 (deemed insecure). If you still have other clients expecting modp1024, make it:
>> 
>> aes256-3des-sha256-sha1-modp2048-modp1024
>> 
>> That should get you covered. 
>> 
>> Regards,
>> Jafar
>> 
>> 
>> On 5/7/2018 8:17 AM, Houman wrote:
>>> Hello,
>>> 
>>> Until a week ago a user with Windows 10 had no issue connecting to the StrongSwan server. But now out of the blue, he can't connect to the StrongSwan server anymore.
>>> 
>>> The log on the server is:
>>> 
>>> May  7 12:31:06 vpn-p1 charon: 08[IKE] received proposals inacceptable
>>> May  7 12:31:06 vpn-p1 charon: 08[ENC] generating IKE_SA_INIT response 0 [ N(NO_PROP) ]
>>> May  7 12:31:06 vpn-p1 charon: 08[NET] sending packet: from xxx.x.xx.92[500] to 91.98.xxx.xxx[500] (36 bytes)
>>> May  7 12:32:09 vpn-p1 systemd[1]: Started Session 35 of user root.
>>> May  7 12:46:21 vpn-p1 systemd[1]: Starting Cleanup of Temporary Directories...
>>> May  7 12:46:21 vpn-p1 systemd-tmpfiles[7016]: [/usr/lib/tmpfiles.d/var.conf:14] Duplicate line for path "/var/log", ignoring.
>>> May  7 12:46:21 vpn-p1 systemd[1]: Started Cleanup of Temporary Directories.
>>> May  7 13:00:13 vpn-p1 systemd[1]: Starting Certbot...
>>> May  7 13:00:13 vpn-p1 systemd[1]: Started Certbot.
>>> May  7 13:08:20 vpn-p1 systemd[1]: Started Session 36 of user root.
>>> May  7 13:11:27 vpn-p1 charon: 12[NET] received packet: from 91.98.xxx.xxx[500] to xxx.x.xx.92[500] (624 bytes)
>>> May  7 13:11:27 vpn-p1 charon: 12[ENC] parsed IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) V V V V ]
>>> May  7 13:11:27 vpn-p1 charon: 12[IKE] received MS NT5 ISAKMPOAKLEY v9 vendor ID
>>> May  7 13:11:27 vpn-p1 charon: 12[IKE] received MS-Negotiation Discovery Capable vendor ID
>>> May  7 13:11:27 vpn-p1 charon: 12[IKE] received Vid-Initial-Contact vendor ID
>>> May  7 13:11:27 vpn-p1 charon: 12[ENC] received unknown vendor ID: 01:52:8b:bb:c0:06:96:12:18:49:ab:9a:1c:5b:2a:51:00:00:00:02
>>> May  7 13:11:27 vpn-p1 charon: 12[IKE] 91.98.xxx.xxx is initiating an IKE_SA
>>> May  7 13:11:27 vpn-p1 charon: 12[CFG] received proposals: IKE:AES_CBC_256/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_2048, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048, IKE:AES_CBC_256/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_2048
>>> May  7 13:11:27 vpn-p1 charon: 12[CFG] configured proposals: IKE:AES_GCM_16_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_521, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_384, IKE:AES_CBC_256/3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
>>> May  7 13:11:27 vpn-p1 charon: 12[IKE] remote host is behind NAT
>>> May  7 13:11:27 vpn-p1 charon: 12[IKE] received proposals inacceptable
>>> May  7 13:11:27 vpn-p1 charon: 12[ENC] generating IKE_SA_INIT response 0 [ N(NO_PROP) ]
>>> May  7 13:11:27 vpn-p1 charon: 12[NET] sending packet: from xxx.x.xx.92[500] to 91.98.xxx.xxx[500] (36 bytes)
>>> May  7 13:11:28 vpn-p1 charon: 16[NET] received packet: from 91.98.xxx.xxx[500] to xxx.x.xx.92[500] (624 bytes)
>>> May  7 13:11:28 vpn-p1 charon: 16[ENC] parsed IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) V V V V ]
>>> May  7 13:11:28 vpn-p1 charon: 16[IKE] received MS NT5 ISAKMPOAKLEY v9 vendor ID
>>> May  7 13:11:28 vpn-p1 charon: 16[IKE] received MS-Negotiation Discovery Capable vendor ID
>>> May  7 13:11:28 vpn-p1 charon: 16[IKE] received Vid-Initial-Contact vendor ID
>>> May  7 13:11:28 vpn-p1 charon: 16[ENC] received unknown vendor ID: 01:52:8b:bb:c0:06:96:12:18:49:ab:9a:1c:5b:2a:51:00:00:00:02
>>> May  7 13:11:28 vpn-p1 charon: 16[IKE] 91.98.xxx.xxx is initiating an IKE_SA
>>> May  7 13:11:28 vpn-p1 charon: 16[CFG] received proposals: IKE:AES_CBC_256/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_2048, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048, IKE:AES_CBC_256/HMAC_SHA2_384_192/PRF_HMAC_SHA2_384/MODP_2048
>>> May  7 13:11:28 vpn-p1 charon: 16[CFG] configured proposals: IKE:AES_GCM_16_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_521, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_384, IKE:AES_CBC_256/3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
>>> May  7 13:11:28 vpn-p1 charon: 16[IKE] remote host is behind NAT
>>> May  7 13:11:28 vpn-p1 charon: 16[IKE] received proposals inacceptable
>>> May  7 13:11:28 vpn-p1 charon: 16[ENC] generating IKE_SA_INIT response 0 [ N(NO_PROP) ]
>>> May  7 13:11:28 vpn-p1 charon: 16[NET] sending packet: from xxx.x.xx.92[500] to 91.98.xxx.xxx[500] (36 bytes)
>>> 
>>> The Server's ipsec.conf is:
>>> 
>>> config setup
>>>   strictcrlpolicy=yes
>>>   uniqueids=never
>>> conn roadwarrior
>>>   auto=add
>>>   compress=no
>>>   type=tunnel
>>>   keyexchange=ikev2
>>>   fragmentation=yes
>>>   forceencaps=yes
>>>   ike=aes256gcm16-sha256-ecp521,aes256-sha256-ecp384,aes256-3des-sha1-modp1024!
>>>   esp=aes256gcm16-sha256,aes256-3des-sha256-sha1!
>>>   dpdaction=clear
>>>   dpddelay=180s
>>>   rekey=no
>>>   left=%any
>>>   leftid=@${VPNHOST}
>>>   leftcert=cert.pem
>>>   leftsendcert=always
>>>   leftsubnet=0.0.0.0/0 <http://0.0.0.0/0>
>>>   right=%any
>>>   rightid=%any
>>>   rightauth=eap-radius
>>>   eap_identity=%any
>>>   rightdns=208.67.222.222,208.67.220.220
>>>   rightsourceip=${VPNIPPOOL}
>>>   rightsendcert=never
>>> 
>>> Have the supported ike/esp proposals somehow been changed recently after a recent Windows 10 update?
>>> 
>>> I have made these changes on the Windows 10, after googling for a solution:
>>> 
>>> - The firewall on Windows 10 is currently disabled.  
>>> - I have set NegotiateDH2048_AES256 = 1 in Regedit
>>> - AssumeUDPEncapsulationContextOnSendRule = 2 in Regedit
>>> 
>>> I can't think of anything else I could do on the Windows 10 client.
>>> 
>>> According to my notes, these are the proposed protocols for Windows 10:
>>> 
>>> # these ike and esp settings are tested on Mac 10.12, iOS 10 and Windows 10
>>> # iOS/Mac with appropriate configuration profiles use AES_GCM_16_256/PRF_HMAC_SHA2_256/ECP_521
>>> # Windows 10 uses AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_384
>>> 
>>> Is there a website that translates AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_384 into the right naming for ipsec.conf so that I enter them under ike and esp respectively? I can't quite make out if I have these settings there or not.
>>> 
>>> If you have any other advice, please help me.
>>> 
>>> Many Thanks,
>>> 
>>> 
>>> 
>>> 
>> 
> 
> 

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