Hi,
On Sat, Sep 28, 2024 at 10:00:01AM +0800, jeremy ardley wrote:
> On 28/9/24 06:42, Andy Smith wrote:
> > # ip address add 85.119.82.225/32 dev enX0
> > # ip -4 route add default via inet6 fe80::1 src 85.119.82.225
> >
> > Is it possible to configure that using ifupdown's
> > /etc/network/interfaces syntax?
[…]
> > Is it doable with any of the other network configuration frameworks
> > (systemd-networkd, NetworkManager, netplan, …)?
[…]
> In regard to systemd-networkd and likely all other choices it probably won't
> work.
>
> You would be better off using iptables or nftables to NAT the IPv4 to IPv6
> and route that instead.
Hmm, that is pretty gross since with an IPv6 nexthop there is no NAT
involved at all, only normal layer 3 routing. You would actually have to
NAT it twice (464XLAT) as otherwise the traffic comes out as IPv6 and
not the original global IPv4 addresses.
It seems a pretty excessive thing to do when the Linux kernel does
support just plain routing of IPv4 packets through IPv6 destinations and
the only thing missing here is seemingly distribution integration.
If you had no network configuration framework at all and just set up
your networking with a shell script, this would work. I think it could
also work with ifupdown if you abused pre-up commands, which would
certainly be preferable to two layers of NAT!
Something like
auto enX0
iface enX0 inet
address 85.119.82.225/32
pre-up ip -4 route add default via inet6 fe80::1 dev $IFACE src
85.119.82.225
could probably do it…
I probably won't though as chances are I will end up wanting to use
something other than ifupdown at some point, and then I'd be stuffed.
I'll just wait for the various frameworks to gain the features that
"ip" already supports I guess! (💀)
Thanks,
Andy
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