[Swan] Wildcarding rightid

Messa, Michael - 0664 - MITLL mmessa at ll.mit.edu
Fri Apr 5 12:56:26 UTC 2019


First off, thank you very much for taking the time to respond. 

To provide slightly more context, I'm in a position where I am attempting to provide an IPSEC implementation that is compliant with a 'specification, as written'. Part of my mission is to evaluate the specification for buildability and to identify holes. Since LibreSwan is the de-facto IPSEC implementation on many commercial platforms I wanted to make sure I could achieve interoperability with this spec using LibreSwan. 

"If that is a fixed string, why can't that the peer ID known to the client?"

There is currently no mechanism defined for this ID to get to the client in this spec. I've identified this as a potential hole but received pushback because "it works with StrongSwan".  

"We currently do not support this."

Thank you for confirming. To me this actively demonstrates that this particular scenario is atypical. 

"I still cannot imagine a scenario where the constraints you mention are a valid set of constraints for deployment."

I concur. The counter argument I've received is that the PSK alone is sufficient to anchor the trust between the client and the server and that the IDr in this case is not consequential. 

If you have any further thoughts on the matter feel free to share. Thanks again for your time. 


-----Original Message-----
From: Paul Wouters <paul at nohats.ca> 
Sent: Friday, April 05, 2019 4:40 AM
To: Messa, Michael - 0664 - MITLL <mmessa at ll.mit.edu>
Cc: swan at lists.libreswan.org
Subject: Re: [Swan] Wildcarding rightid

On Tue, 2 Apr 2019, Messa, Michael - 0664 - MITLL wrote:

> I am attempting to configure a client to connect with a server in 
> tunnel mode where the client does not know the ID of the server prior to initiating the key exchange, and the authentication uses a pre-shared key (PSK).

That is a very strange scenario.

> The server is required to
> identify itself for authentication using a fixed, verbatim identification string.

If that is a fixed string, why can't that the the peer ID known to the client?

> The client’s sole existence is to connect to only this one server.

The term "only this one server" is based on the PSK without ID? That is a strange concept of authentication of identity.

> Using StrongSwan I’ve been able to configure a client with a 
> “rightid=%any”, which effectively allows me to wildcard the IDr in the IKE. Does LibreSwan offer such a flexibility? If so, what is the appropriate configuration. I’ve tried “rightid=%any”
> despite no documentation saying it was supported. The result was that 
> rightid defaulted to right (as described in the
> documentation) and the IKE fails with an error like:

We currently do not support this. It would be possible to add, but I would really need to understand the use case first because I still cannot imagine a scenarion where the constrains you mention are a valid set of constrains for deployment.


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