[strongSwan] SHA1 vs SHA256

[Andreas Steffen]

Hi Dusan,

hmmm, our documentation says that the correct ESP SHA256_128 HMAC
truncation was introduced with the 2.6.33 kernel but your kernel
might not be a vanilla 2.6.36 kernel:

 https://wiki.strongswan.org/projects/strongswan/wiki/IKEv2CipherSuites

 (ESP integrity algorithm footnote n)

Regards

Andreas

On 04.08.2017 16:41, Dusan Ilic wrote:
> Hi Andreas
> 
> One side is 2.6.36 and the other 3.10.20
> 
> 
> Den 2017-08-04 kl. 12:48, skrev Andreas Steffen:
>> Hi Dusan,
>>
>> this is a Linux kernel issue. Which kernel versions are you running
>> on the two endpoints?.
>>
>> Regards
>>
>> Andreas
>>
>> On 04.08.2017 12:41, Dusan Ilic wrote:
>>> Hi Noel,
>>>
>>> One side is Strongswan 5.2.2 and the other is 5.5.2.
>>> How do I switch?
>>>
>>>
>>> Den 2017-08-04 kl. 12:25, skrev Noel Kuntze:
>>>> the remote peer probably uses the DRAFT variant of sha2-256, which
>>>> uses 96 bit truncation. strongSwan uses the actual standardized
>>>> variant that truncates to 128 bit.
>>>> You can switch between the two in the newest version of strongSwan
>>>>
>>>> On 04.08.2017 12:23, Dusan Ilic wrote:
>>>>> Hello!
>>>>>
>>>>> I have a strange issue, with both settings below the tunnel goes up
>>>>> as it should, but only with SHA1 in ESP traffic goes through. When I
>>>>> ping the remote client with ESP SHA256 it times out, even though the
>>>>> tunnel reports as being up by Strongswan.
>>>>>
>>>>> Traffic working:
>>>>>
>>>>> ike=aes256-sha256-modp2048!
>>>>> esp=aes128-sha1-modp2048!
>>>>>
>>>>> Traffic not working:
>>>>>
>>>>> ike=aes256-sha256-modp2048!
>>>>> esp=aes256-sha256-modp2048!
>>>>>
>>>>> Below combo doesn't work either:
>>>>>
>>>>> ike=aes256-sha256-modp2048!
>>>>> esp=aes128-sha256-modp2048!
>>>>>
>>>>>
>>>>> Also, are above settings good? I'm having AES128 on ESP because with
>>>>> AES256 I loose too much througput. Do you have any suggestions for
>>>>> change?
>>>>>
>>>>>
> 

-- 
======================================================================
Andreas Steffen                         andreas.steffen at strongswan.org
strongSwan - the Open Source VPN Solution!          www.strongswan.org
Institute for Networked Solutions
HSR University of Applied Sciences Rapperswil
CH-8640 Rapperswil (Switzerland)
===========================================================[INS-HSR]==

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