Re: IPIP tunnel peer ipv4 address

[Radu Rendec <radu rendec mindbit ro>]

On Mon, 2017-04-10 at 15:58 +0200, Thomas Haller wrote:
> On Fri, 2017-04-07 at 13:43 +0100, Radu Rendec wrote:
> > I'm trying to setup an IPIP tunnel using nmcli. I can create the
> > tunnel
> > using, e.g.:
> >
> > nmcli con add type ip-tunnel mode ipip ifname tun0 remote 10.0.4.1
> > local 10.0.8.1
> >
> > And then I can assign an ipv4 address using:
> >
> > nmcli con mod ip-tunnel-tun0 ipv4.address 192.168.9.1
> >
> > However, I'm not able to set the peer ipv4 address (the "inner"
> > address
> > of the remote end of the tunnel). What I'm looking for is the NM
> > equivalent of this:
> >
> > ip addr add 192.168.9.1 peer 192.168.9.2 dev tun0
> >
> > What is the NM way to configure something similar to the above?
>
> NM doesn't support setting peers for IP addresses.
>
> You might be able to use a dispatcher script (man NetworkManager),
> but that is not great workaround.
>
>
> Could you elaborate why you need that?

Hi Thomas,

Thanks for the feedback. I basically need a route to the peer. When the
IP address is configured with a peer, the kernel adds an implicit route
to it. I was hoping to achieve the same with NM.

As a workaround, I explicitly set a manual route to the peer and it
works. But this is just a ... workaround and I was hoping there was a
cleaner way to do this.

Anyway, before initially posting to the list, I had a quick look at the
NM sources. It seemed to me that there's at least partial support for
the PTP address, because:
 * NMPlatformIP4Address contains a peer_address field which, according
   to the comment in src/platform/nm-platform.h (where the actual
   struct is defined) seems to be the right thing.
 * This field seems to be handled down the path of nm_ip4_config_commit
   nm_platform_ip4_address_sync, nm_platform_ip4_address_add,
   ip4_address_add and _nl_msg_new_address.

However, I'm new to the NM code base and I may very well be misreading
it. Besides, the path that I highlighted only deals with NM to kernel
sync, but doesn't say anything about the NM config and D-Bus side. In
any case, I thought I was better off asking around than reading and
trying to understand more of the code :)

Thanks,
Radu