[strongSwan] SHA1 vs SHA256
Dusan Ilic
dusan at comhem.se
Tue Aug 8 19:32:47 CEST 2017
Strongswan 5.2.2
# ip xfrm state
src 94.254.123.x dst 85.24.241.x
proto esp spi 0xc713c2af reqid 1 mode tunnel
replay-window 32 flag af-unspec
auth-trunc hmac(sha256)
0x6f7a3562e5e18fafa95683bf589c6c98c2be237732a5403e22a3e48c65654314 128
enc cbc(aes)
0x77bbcc462b7217af56052a6cb6c008af4052542a13d674e1d6136f6df9c8522e
src 85.24.241.x dst 94.254.123.x
proto esp spi 0xce1e5159 reqid 1 mode tunnel
replay-window 32 flag af-unspec
auth-trunc hmac(sha256)
0x37110356f80804e83ceb23ecb4e7be5508445a4fdd0eb4814dbdde00dffa6033 128
enc cbc(aes)
0x903c3c6c98c90f49102e839badfc7baa5ee38cf89c9ae0013c75b6556a06a345
# ip -s x s s
src 94.254.123.x dst 85.24.241.x
proto esp spi 0xc713c2af(3339961007) reqid 1(0x00000001) mode
tunnel
Strongswan 5.5.2
# ip xfrm state
src 85.24.241.x dst 94.254.123.x
proto esp spi 0xce1e5159 reqid 1 mode tunnel
replay-window 0 flag nopmtudisc af-unspec
auth-trunc hmac(sha256)
0x37110356f80804e83ceb23ecb4e7be5508445a4fdd0eb4814dbdde00dffa6033 128
enc cbc(aes)
0x903c3c6c98c90f49102e839badfc7baa5ee38cf89c9ae0013c75b6556a06a345
src 94.254.123.x dst 85.24.241.x
proto esp spi 0xc713c2af reqid 1 mode tunnel
replay-window 32 flag nopmtudisc af-unspec
auth-trunc hmac(sha256)
0x6f7a3562e5e18fafa95683bf589c6c98c2be237732a5403e22a3e48c65654314 128
enc cbc(aes)
0x77bbcc462b7217af56052a6cb6c008af4052542a13d674e1d6136f6df9c8522e
# ip -s x s s
src 85.24.241.x dst 94.254.123.x
proto esp spi 0xce1e5159(3458093401) reqid 1(0x00000001) mode
tunnel
replay-window 0 seq 0x00000000 flag nopmtudisc af-unspec
(0x00100100)
auth-trunc hmac(sha256)
0x37110356f80804e83ceb23ecb4e7be5508445a4fdd0eb4814dbdde00dffa6033 (256
bits) 128
enc cbc(aes)
0x903c3c6c98c90f49102e839badfc7baa5ee38cf89c9ae0013c75b6556a06a345 (256
bits)
lifetime config:
limit: soft (INF)(bytes), hard 104857600(bytes)
limit: soft (INF)(packets), hard (INF)(packets)
expire add: soft 2522(sec), hard 3600(sec)
expire use: soft 0(sec), hard 0(sec)
lifetime current:
6984(bytes), 94(packets)
add 2017-08-08 19:23:29 use 2017-08-08 19:23:48
stats:
replay-window 0 replay 0 failed 0
src 94.254.123.x dst 85.24.241.x
proto esp spi 0xc713c2af(3339961007) reqid 1(0x00000001) mode
tunnel
replay-window 32 seq 0x00000000 flag nopmtudisc af-unspec
(0x00100100)
auth-trunc hmac(sha256)
0x6f7a3562e5e18fafa95683bf589c6c98c2be237732a5403e22a3e48c65654314 (256
bits) 128
enc cbc(aes)
0x77bbcc462b7217af56052a6cb6c008af4052542a13d674e1d6136f6df9c8522e (256
bits)
lifetime config:
limit: soft (INF)(bytes), hard 104857600(bytes)
limit: soft (INF)(packets), hard (INF)(packets)
expire add: soft 2717(sec), hard 3600(sec)
expire use: soft 0(sec), hard 0(sec)
lifetime current:
0(bytes), 0(packets)
add 2017-08-08 19:23:29 use 2017-08-08 19:23:37
stats:
replay-window 0 replay 0 failed 24
Den 2017-08-08 kl. 18:43, skrev Noel Kuntze:
> Hi Dusan,
>
> I think it'd be useful, if you could post complete outputs of `ip xfrm state` of both hosts.
> The last time you posted them, one of the outputs was incomplete and cut off just above the relevant lines
>
> Kind regards
>
> Noel
>
> On 08.08.2017 18:36, Dusan Ilic wrote:
>>> Hi Thomas, > > I tried your suggested proposal, but that doesnt work either. > > Unfortunately, both endpoints are Linux embedded (routers), so I think that isn't an option. > However, I see that in version 5.5.3 there is a new option in Strongswan. > > /sha256_96 = *no* | yes/ > > HMAC-SHA-256 is used with 128-bit truncation with IPsec. For compatibility with implementations that incorrectly use 96-bit > truncation this option may be enabled to configure the shorter truncation length in the kernel. This is not negotiated, so this > only works with peers that use the incorrect truncation length (or have this option enabled). Available since 5.5.3 <https://wiki.strongswan.org/versions/65>. > > > > Maybe I'll have to wait for the next version beeing released in the repository on the endpoint currently running 5.5.2. > > Just to clarify, which of the endpoints are the failing endpoint here? I mean, which endpoint is truncating it to 96 bits? > > > Den 2017-08-08 kl. 09:39,
> skrev Thomas Egerer:
>> Hi Dusan,
>>
>> On 08/06/2017 08:13 PM, Dusan Ilic wrote:
>>>>> Hi Thomas,
>>>>>
>>>>> I haven't upgraded it cause that's not an option, both endpoints are routers with Linux embedded.
>>>>> Below is the output after some pings from both sides.
>>>>>
>>>>> Strongswan 5.5.2
>>>>>
>>>>> ip -s x s s
>>>>> src 85.24.241.x dst 94.254.123.x
>>>>> proto esp spi 0xce291943(3458799939) reqid 1(0x00000001) mode tunnel
>>>>> replay-window 0 seq 0x00000000 flag nopmtudisc af-unspec (0x00100100)
>>>>> auth-trunc hmac(sha256) 0xc45dd8403c10cfd32f8fe74003cc80a309b7a0decb185826ef62ac1763ae4bcd (256 bits) 128
>>>>> enc cbc(aes) 0x0abb9115383986028a844ff1e71bd0f55aa22099d76785b288803ed7204aa23e (256 bits)
>>>>> lifetime config:
>>>>> limit: soft (INF)(bytes), hard (INF)(bytes)
>>>>> limit: soft (INF)(packets), hard (INF)(packets)
>>>>> expire add: soft 2762(sec), hard 3600(sec)
>>>>> expire use: soft 0(sec), hard 0(sec)
>>>>> lifetime current:
>>>>> 1416(bytes), 25(packets)
>>>>> add 2017-08-06 20:08:26 use 2017-08-06 20:08:31
>>>>> stats:
>>>>> replay-window 0 replay 0 failed 0
>>>>> src 94.254.123.x dst 85.24.241.x
>>>>> proto esp spi 0xc9359a4e(3375733326) reqid 1(0x00000001) mode tunnel
>>>>> replay-window 32 seq 0x00000000 flag nopmtudisc af-unspec (0x00100100)
>>>>> auth-trunc hmac(sha256) 0xfe9408ba634fe4276972fa79c9b60f12bffc766434298cb25738396d2b94dda9 (256 bits) 128
>>>>> enc cbc(aes) 0x1fd6fd06781cee3bab6ed97a2f01793eded22f7360691430fdfb604c4e424066 (256 bits)
>>>>> lifetime config:
>>>>> limit: soft (INF)(bytes), hard (INF)(bytes)
>>>>> limit: soft (INF)(packets), hard (INF)(packets)
>>>>> expire add: soft 2895(sec), hard 3600(sec)
>>>>> expire use: soft 0(sec), hard 0(sec)
>>>>> lifetime current:
>>>>> 0(bytes), 0(packets)
>>>>> add 2017-08-06 20:08:26 use 2017-08-06 20:08:28
>>>>> stats:
>>>>> replay-window 0 replay 0 failed 49
>> ^^- this indicates a crypto-
>> graphic error with the received packets. As suspected in this thread
>> before, your peer -- which by the way has a very very sparse iproute2
>> output, did it get truncated -- most likely uses sha256 with a 96 bit
>> truncation.
>> - From quickly reading this entire thread I did not whether you have
>> tried the following proposal on both sides:
>>
>> esp=aes128-sha256_96-modp2048!
>>
>> Is building your own strongswan instance for the regular linux box an
>> option for you?
>>
>> Cheers, Thomas
>>>>> Strongswan 5.2.2
>>>>>
>>>>> ip -s x s s
>>>>> src 94.254.123.x dst 85.24.241.x
>>>>> proto esp spi 0xc9359a4e(3375733326) reqid 1(0x00000001) mode tunnel
>>>>>
>>>>> Den 2017-08-06 kl. 16:49, skrev Thomas Egerer:
>>>>> Hello Dusan,
>>>>>
>>>>> if you haven't yet updated your kernel, we might shed some light on
>>>>> the problem. Set up the tunnel with SHA256 and send a couple of
>>>>> packets from both sides. Then provide the output of
>>>>> 'ip -s x s s'
>>>>>
>>>>> Cheers,
>>>>> Thomas
>>>>>
>>>>>
>>>>> On 08/04/2017 12:23 PM, 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?
>>>>>>>>
>>>>>>>>
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