netplan-developers team mailing list archive

[Jason Heeris <jason.heeris@xxxxxxxxx>]

On Wed, Jun 13, 2018 at 10:00 PM, Jason Heeris <jason.heeris@xxxxxxxxx> 
wrote:
> Doing this made me realise also - I have to recreate those routing 
> table entries I wanted to get rid of anyway. Otherwise the eth-wifi 
> bridge can't work, because nothing will get routed out of the 
> wlx485d601f9b83 interface. (The other part to the bridge is a "-A 
> POSTROUTING -s 10.0.0.0/24 -o wlx485d601f9b83 -j MASQUERADE" entry in 
> iptables' NAT table.) So I seem to be stuck with having everything 
> think it can go out via wlx485d601f9b83, or nothing. This is getting 
> beyond the scope of Netplan perhaps, but if you have advice I'll 
> happily take pointers.

Well, I'm getting warmer at least. I need an extra routing table, so 
doing this manually:

$ sudo ip route del 192.168.1.0/24 dev wlx485d601f9b83
$ sudo ip rule add from 10.0.0.0/24 table ewrelay
$ sudo ip route add default via 192.168.1.1 dev wlx485d601f9b83 table 
ewrelay

Giving:

$ ip route show
default via 192.168.1.1 dev wlp2s0 proto dhcp src 192.168.1.100 metric 
600
10.0.0.0/24 dev enp1s0f0 proto kernel scope link src 10.0.0.1
192.168.1.0/24 dev wlp2s0 proto kernel scope link src 192.168.1.100
192.168.1.1 dev wlp2s0 proto dhcp scope link src 192.168.1.100 metric 
600
$ ip route show table ewrelay
default via 192.168.1.1 dev wlx485d601f9b83
$ ip rule show
0:	from all lookup local
32765:	from 10.0.0.0/24 lookup ewrelay
32766:	from all lookup main
32767:	from all lookup default

...got things working. Kind of. For five minutes*. I can almost 
recreate this with Netplan using:

 ethernets:
   enp1s0f0:
     optional: false
     addresses:
       - 10.0.0.1/24
 wifis:
   wlx485d601f9b83:
     optional: true
     addresses: [192.168.1.110/32]
     routes:
       - to: 0.0.0.0/0
         via: 192.168.1.1
         table: 12
     routing-policy:
       - from: 10.0.0.0/24
         table: 12
     access-points:
       [...]

EXCEPT that I can't figure out how to keep the "192.168.1.0/24 dev 
wlx485d601f9b83" off the default routing table. If it's there, nothing 
gets routed out of wlp2s0. If I set the subnet specifier to /32, 
*nothing* gets routed out of wlx485d601f9b83 (even though the routing 
table looks identical to the sort-of-working one, 'ip route get to 
8.8.8.8 from 10.0.0.1' returns different results).

Furthermore, despite setting a static address on enp1s0f0 and setting 
the wifi interfaces to "optional: true", my boot now takes several 
minutes (sometimes) while "A start job is running for Wait for Network 
to be Configured". When this happens, I'll also see that the 
isc-dhcp-server has failed to start because it's "Not configured to 
listen on any interfaces!" (it is definitely configured to listen on 
enp1s0f0). I had thought the whole point of a static config on enp1s0f0 
was to avoid this sort of thing, but again, there's a lot about this I 
find confusing.

*Saying whether or not something works is made difficult by the fact 
that it's not even remotely deterministic. Sometimes I can reboot four 
or five times with the exact same config and things suddenly work, 
sometimes I won't change anything and it'll all break. This is probably 
due to a configuration problem too? But there are so many more moving 
parts than I can keep track of, it's mostly just guesswork on my part.

- Jason