[Swan] mac and win10 ikev2

[Paul Wouters]

On Tue, 19 Dec 2017, Computerisms Corporation wrote:

> For the firewall cert (not sure if it is required, but in the troubleshooting 
> process I ended up adding it) I put a DNS: SubjectAltName as well as an IP: 
> SubjectAltName.

It is required. Whatever the ID you use in the xml, that has to be a SAN
on the cert. So if your ID is an IP, you need the IP: SAN. If you use a
hostname as ID, you need to have the hostname on the SAN.

> The default ike and phase2alg settings didn't work for neither of windows 7, 
> windows 10, or mac os 10.10, at least for me.  I had to adjust them according 
> to the proposals I found in the logs.

yes, because of a bug in Windows IKEv2. This is known by them as:

 	MSRC Case Opened: 35732 - IKEv2 - Diffie-Hellman to MODP-1024 Bypass TRK:0901001101

I filed it in October 2016. The latest update on this is that it will be
fixed in "Spring 2018".

> My working conn:

> ike=aes256-sha384-modp1024,aes256-sha256-modp2048,aes256-sha512-modp8192,aes256-sha512-modp2048
>    phase2alg=aes256-sha1,aes256-sha512;modp4096

You should put the weak modp1024 in the end so that the proposal is the
least favourite. That way clients announcing support for weak and strong
will get strong instead of weak. I use:

 	ike=aes256-sha2_512;modp2048,aes128-sha2_512;modp2048,aes256-sha1;modp1024,aes128-sha1;modp1024
 	esp=aes_gcm256-null,aes_gcm128-null,aes256-sha2_512,aes128-sha2_512

This also prefers AES_GCM over AES for ESP, since it is stronger and
takes up a lot less CPU.

Paul