[Swan] LibreSWAN and IPv6 Link Local addresses

William Atwood william.atwood at concordia.ca
Fri Jan 26 19:31:51 EET 2024


Brady,

I am not trying to create a user-level interface with a specific 
address.  I am trying to get Libreswan to accept that a given, existing 
Link-Local (LL) address is a valid endpoint for a Security Association.  
Please read issue #1498 on the Github site for the details.  The message 
was intended to demonstrate to Tuomo that Libreswan actively asserts 
that LL addresses are not acceptable.

   Bill

On 1/26/2024 8:38 AM, Brady Johnson wrote:
>
> Attention This email originates from outside the concordia.ca domain. 
> // Ce courriel provient de l'extérieur du domaine de concordia.ca
>
>
>
>
> Bill,
>
> To be able to "invoke" XFRM in the config you listed, you need to add 
> the following 2 parameters:
>
>     ipsec-interface=1
>     leftinterface-ip=<your IPv6 with netmask>
>
>
> The "ipsec-interface=1" parameter will create an interface called 
> ipsec01, and the other parameter will set the IP on that interface.
>
> Regards,
>
> *Brady Johnson*
> Principal Software Engineer
> Telco Solutions & Enablement
> brady.johnson at redhat.com
>
>
>
> On Fri, Jan 26, 2024 at 4:28 AM William Atwood 
> <william.atwood at concordia.ca> wrote:
>
>     Tuomo,
>
>     I apologize for disagreeing, but Libreswan not only does not support
>     Link-Local addresses, but it actively declares that they are not
>     usable.
>       I agree that making Libreswan process Link-Local addresses properly
>     will not be possible until XFRM is fixed, but in the case outlined
>     below, it appears that XFRM is not even invoked.
>
>     I have two hosts, with a shared LAN, called Gingko and Ritchie, both
>     running Libreswan 5.0rc1.
>
>     File GIRI6CL.conf on Gingko:
>     conn GIRI6cl
>         left=fe80::20e:cff:fe9c:d92d%ens7
>         leftid="CN=Gingko Certificate"
>         leftrsasigkey=%cert
>         leftcert=GIcert
>         right=fe80::20e:cff:fea9:b90f%ens7
>         rightid="CN=Ritchie Certificate"
>         rightrsasigkey=%cert
>         auto=add
>
>     File RIGI6CL.conf on Ritchie:
>     conn RIGI6cl
>         left=fe80::20e:cff:fea9:b90f%enp5s4
>         leftid="CN=Ritchie Certificate"
>         leftrsasigkey=%cert
>         leftcert=RIcert
>         right=fe80::20e:cff:fe9c:d92d%enp5s4
>         rightid="CN=Gingko Certificate"
>         rightrsasigkey=%cert
>         auto=add
>
>     On Ritchie:
>     dev at Ritchie:~$ sudo ipsec add RIGI6cl
>     "RIGI6cl": added IKEv2 connection
>     dev at Ritchie:~$
>
>     On Gingko:
>     dev at Gingko:~$ sudo ipsec add GIRI6cl
>     "GIRI6cl": added IKEv2 connection
>     dev at Gingko:~$ sudo ipsec up GIRI6cl
>     "GIRI6cl": we cannot identify ourselves with either end of this
>     connection.  fe80::20e:cff:fe9c:d92d or fe80::20e:cff:fea9:b90f
>     are not
>     usable
>     dev at Gingko:~$
>
>     The listed Link-Local addresses are correct; I can " ping -6
>     fe80::20e:cff:fea9:b90f%ens7" on Gingko, and get the appropriate
>     response from Ritchie, and I can " ping -6
>     fe80::20e:cff:fe9c:d92d%enp5s4" from Ritchie, and get the appropriate
>     response from Gingko.
>
>     Finally, if I assign Unique Local Addresses to the same two
>     interfaces,
>     and use these addresses in the above .conf files, the Security
>     Association establishes perfectly.
>
>     Therefore, I believe that your statement that "Global is only used
>     when
>     adding IP for XFRM interface for route-based IPsec vpn." is
>     incorrect.
>     Clearly, Libreswan has code somewhere that is rejecting non-global
>     addresses for simple, tunnel-mode Security Associations between two
>     adjacent hosts.
>
>     Andrew has put a milestone of Release 5.1 on my issue #1498, which
>     provides justification for the use of Link-Local addresses as valid
>     endpoints.  I hope that XFRM has been fixed by the time 5.1 is
>     released.
>
>        Bill
>
>     On 1/17/2024 1:24 AM, Tuomo Soini wrote:
>     > Attention This email originates from outside the concordia.ca
>     <http://concordia.ca/> domain. // Ce courriel provient de
>     l'extC)rieur du domaine de concordia.ca <http://concordia.ca/>
>     >
>     > On Tue, 16 Jan 2024 21:17:41 -0500
>     > William Atwood <william.atwood at concordia.ca> wrote:
>     >
>     >> 1) I know that Libreswan does not support %zone identifiers
>     >> associated with Link-Local (LL) addresses, and it appears from your
>     >> experience that Strongswan does not either.  I also know that
>     >> Libreswan insists that an endpoint address must be "Global".
>     >
>     > Global is only used when adding IP for XFRM interface for
>     route-based
>     > IPsec vpn. And because this is route-based, this can't be
>     LL-address.
>     > We told you multiple times that this doesn't affect LL address
>     > handling. And we can't really implement support for LL addresses on
>     > linux before XFRM/IPsec stack supports it.
>     >
>
>     -- 
>     Dr. J.W. Atwood, Eng.             tel:   +1 (514) 848-2424 x3046
>     Distinguished Professor Emeritus  fax:   +1 (514) 848-2830
>     Department of Computer Science
>         and Software Engineering
>     Concordia University ER 1234 email:william.atwood at concordia.ca
>     <mailto:email%3Awilliam.atwood at concordia.ca>
>     1455 de Maisonneuve Blvd. West http://users.encs.concordia.ca/~bill
>     Montreal, Quebec Canada H3G 1M8
>
>     _______________________________________________
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>     Swan at lists.libreswan.org
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>
-- 
Dr. J.W. Atwood, Eng.             tel:   +1 (514) 848-2424 x3046
Distinguished Professor Emeritus  fax:   +1 (514) 848-2830
Department of Computer Science
    and Software Engineering
Concordia University ER 1234email:william.atwood at concordia.ca
1455 de Maisonneuve Blvd. Westhttp://users.encs.concordia.ca/~bill
Montreal, Quebec Canada H3G 1M8
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