[Swan] windows 10 Policy Match Error

[Paul Wouters]

Modp1024 is no longer supported by default compile options. It is simply too weak and can be cracked using academic size resources (eg a small cluster at a university)

Microsoft really needs to step up their IPsec maintenance.

Paul

Sent from my iPhone

> On Oct 4, 2019, at 14:29, Computerisms Corporation <bob at computerisms.ca> wrote:
> 
> Hi Again,
> 
> Turns out that brand new laptop still does connect so long as I do not specify an ike/esp line.  in the debug logs, it seems to choose this proposal:
> 
> IKE:ENCR=AES_CBC_256;INTEG=HMAC_SHA2_256_128;PRF=HMAC_SHA2_256;DH=MODP2048[first-match]
> 
> Not sure how that helps me get the other ones connected, but it is interesting, at least...
> 
> In the debug logs, I think this is the line that indicates what windows is proposing that libreswan is rejecting:
> 
> pluto[30250]: "rw-ikev2"[1] 50.117.137.129 #5: no local proposal matches remote proposals 1:ESP:ENCR=AES_CBC_256;INTEG=HMAC_SHA1_96;ESN=DISABLED 2:ESP:ENCR=3DES;INTEG=HMAC_SHA1_96;ESN=DISABLED
> 
> so I put this in my conn:
> 
> esp=aes256-sha1-modp1024
> 
> and the connection worked.
> 
> so I go back to the wiki, which tells me to use this:
> 
> esp=aes_gcm256-null,aes_gcm128-null,aes256-sha2_512,aes128-sha2_512,aes256-sha1,aes128-sha1,aes_gcm256-null;modp1024
> 
> and I believe from reading the man page on the topic that this should also match the aes256-sha1-modp1024 proposal, however evidence clearly indicates it does not.
> 
> I tried messing with the syntax of the wiki line a bit, but nothing I did worked, really not clear what I am missing.  Did I find a problem that isn't supposed to be there?  Or am I just stuck with only accepting the single esp proposal?
> 
> 
> 
> How do I interpret this and translate it to
> 
>> On 2019-10-04 9:30 a.m., Computerisms Corporation wrote:
>> Hi Nels and Paul,
>> Apologies for the delayed reply, I was overly busy at the moment and duct taped the immediate issue with some iptables rules and port forwarding.  But need something better and I am back to trying to solve this now.
>> I tried setting ikev2 from yes to no, sadly did not change the situation.
>> Oddly enough I put a brand new setup together about a week ago, with a brand new laptop, and it connected fine.  Yesterday I configured a bunch of other laptops to connect to that same firewall, and now nothing connects to it.  That causes me to wonder if a windows update that wasn't installed to begin with is there now on the brand new laptop.
>> Regardless, I faced this problem with windows7 way back, and I managed to solve it that time with a post I found on the strong swan list.  So my instinct is telling me I need to find the correct ike=/esp= lines to fix this problem.  I did find a post from strong swan from Oct/Nov 2018:
>> https://wiki.strongswan.org/issues/2808
>> But none of those cipher lines worked.
>> Similarly there are a set of ciphers listed on the libreswan wiki under the no_proposal_chosen section, and those are not working either.
>> I am thinking the next task is to go through the debug log and find out what proposals windows is expecting, and try to construct appropriate ike=/esp= lines.  I found the parts of the man page that explain how to write the ciphers, but having a hard time translating the log entries into valid cipher descriptions for the conf file.
>> Posting the debug log here in case any one is interested in having a look...
> 
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