[Jool-list] NAT64 behind NAT44?

[Maurice Walker]

Hello Alberto!

> That's what you're trying to do, right? The intended outbound route is
> Client -> Router -> OpenWrt -> Router -> Internet,
> while the intended inbound route is
> Internet -> Router -> OpenWrt -> Client
> Is this correct?

That's exactly right. I know it would be better to run NAT64 on the router
itself, but I don't have that option right now.

> I tried to replicate it yesterday using virtual machines, but was
> having a lot of trouble simply getting the Client -> Router -> OpenWrt
> segment to work. (Which means that my packets didn't even reach Jool.)

That works fine for me. On the router, I created a route for the NAT64
prefix via OpenWrt's LAN address. On OpenWrt I configured the router's
LAN addresses as the default gateways (IPv6 + IPv4). Could have used
link-local addresses, but chose GUAs for simplicity.

> But I do want to let you know that *we might need to wait until next
> week to see any progress*. I'm sorry.

No worries, I'm really thankful that you're taking the time to look into this!

> On the other hand, I can offer releasing commit 89b3c109 as Jool 3.5.8
> right away*.

That would be great. Not sure if it would solve this specific problem, but
ruling out the offloading issue might simplify troubleshooting.

> I don't really know how long would it take for the
> OpenWrt folk to mirror it once that's done.

That might be an issue. It seems it took months for them to switch from
3.5.6 to 3.5.7. But I could try to contact them to speed things up.

> I know that you're not
> very confident about yours being the same problem as issue #267, but
> "TCP Retransmissions, Out-Of-Orders and Dup ACKs" are precisely the
> kind of traffic we get when offloads are not working correctly, and
> that has *everything* to do with issue #267. I cannot guarantee that
> it will solve the problem, but it has a pretty good chance.

That absolutely makes sense. Unfortunately the issues didn't go away
when I was running OpenWrt on actual hardware (an old consumer router
I had laying around). And #267 is specifically about virtual NICs, right?

> Just to confirm: Are offloads disabled?

They are, using ethtool as explained in the Jool documentation. Here is
OpenWrt's /etc/rc.local:

ethtool --offload eth0 gro off
ethtool --offload eth0 lro off
insmod jool disabled=1 pool6=2001:db8:1:64::/96
jool --source-icmpv6-errors-better=on
jool --enable


Maurice