[strongSwan] SHA1 vs SHA256
Dusan Ilic
dusan at comhem.se
Sat Aug 12 00:41:54 CEST 2017
Okey, then I'll probably pass :) I can live without SHA256!
Den 2017-08-11 kl. 21:07, skrev Thomas Egerer:
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> Hi Dusan,
>
> Sorry for the delay. Busy times :)
>
> On 08/09/2017 08:24 AM, Dusan Ilic wrote:
>> How do I do that?
> tcpdump -ni <interface-name> -w /tmp/esp_dump.pcap -s 0 proto 50
> The keys are obtained the same way you did in this mail, by
> running the 'ip -s x s s' command (which by the way is short
> for 'ip -s xfrm state show')
>
> interface-name: e.g. eth0 (or else)
>> Do I have to obfuscate anything sensitive?
> You should be aware of the fact, that anyone with the traffic
> dumps and the keys can decrypt and read the *plain* text of the
> traffic sent over the tunnel (and this includes IP-adresses, too).
>
> Cheers,
> Thomas
>
>> ---- Noel Kuntze skrev ----
>>
>> Hi Dusan,
>>
>> Huh, curious. Both sides use the same keys and the same algorithms with the same block sizes, key sizes and truncation lengths.
>> So this isn't a problem with the truncation length. Do you mind dumping the ESP traffic, saving the keys of the SAs and their corresponding SPIs
>> and sending those things here?
>>
>> Kind regards
>>
>> Noel
>>
>> On 08.08.2017 19:32, Dusan Ilic wrote:
>>> 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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