[Swan] Overlapping traffic selectors and IKEv1

[Paul Wouters]

On Tue, 24 Apr 2018, Ivan Kuznetsov wrote:

> conn aCustomer
>         connaddrfamily=ipv4
>         type=tunnel
>         auto=start
>         authby=secret
>         left=A.B.C.D
>         leftsubnets=30.191.90.169/32,30.191.90.170/32
>         right=E.F.G.H
>         rightsubnets=30.201.192.24/32,30.201.192.34/32
>         ikev2=no
>
> It need to add some customer addresses 30.201.x.y to tunnel. Customer IT 
> service ask me to add the whole network 30.201.0.0/16 to rightsubnet, but for 
> some reason does not remove the subset addresses:
>
>        rightsubnets=30.201.192.24/32,30.201.192.34/32,30.201.0.0/16
>
> Will this configuration work properly for "old" addresses 30.201.192.24 and 
> .34? What is the policy to choose one of overlapping traffic selectors - by 
> longest prefix or someway other?

It should work.

The linux kernel uses priority numbers only, but libreswan does a
translation that maps longest prefix to a priority number.

Paul