[lug] Ubuntu 18.04 Route Metric

[John Hernandez]

In this case, I agree with Zan that the "right way" to fix this is to make
the DHCP server on the private network stop providing a default route.   If
that DHCP server doesn't have the proper knobs to accomplish that, I would
be inclined to turn that DHCP off altogether and deploy a better DHCP
server on the private LAN.

On Fri, May 21, 2021 at 10:24 AM D. Stimits <stimits at comcast.net> wrote:

>
>
> On 05/20/2021 7:01 PM Bear Giles <bgiles at coyotesong.com> wrote:
>
>
> I don't recall if netplan was supported in 18.04. It's taken a bit of time
> to get the hang of it(*) but the basics aren't too bad - it sounds like you
> want to set static values so it should be pretty straightforward.
>
> I want the metric to be custom at low priority (higher metric), or else to
> not have a default route at all on the private network (this is
> preferable). I just don't know how to do this while keeping DHCP.
>
> The private net router is mine, but it seems useless in setting metric.
> I've changed "priority" in "nm-connection-editor", but this is ignored
> (apparently I can set to use DHCP or many other things from
> nm-connection-editor, but priority is summarily ignored). Can netplan be
> used to allow all DHCP, except to intercept metric or default route on one
> interface to either remove default route or force a low priority metric?
> This might be the right way.
>
>
> Part of one of my files is:
>
> # Let NetworkManager manage all devices on this system
> network:
>    version: 2
>    renderer: NetworkManager
>    ethernets:
>      # onboard-NIC
>      enp0s31f6:
>        dhcp4: false
>        addresses:
>         - 192.168.1.3/24
>         - 10.0.10.3/24
>         - 10.0.20.3/24
>         - 10.0.90.3/24
>        # gateway4: 192.168.1.1
>        nameservers:
>          search:
>           - lan
>          addresses:
>           - 10.0.20.15
>           - 10.0.10.10
>           - 8.8.8.8
>        routes:
>          - to: 0.0.0.0/0
>            via: 192.168.1.1
>            metric: 100
>          # home GW to work VPN
>          - to: 172.27.0.0/16
>            via: 192.168.1.200
>            metric: 10
>
> It has additional stanzas for the 10 Gbps(!) NICs. A system with wifi
> connectivity has
>
> # Let NetworkManager manage all devices on this system
> network:
>   version: 2
>   renderer: NetworkManager
>
>   wifis:
>        # all-wlans:
>
>        wlp3s0:
>            match: {}
>            access-points:
>              homewifi:
>                password: 'password'
>            dhcp4: false
>            addresses:
>               - 192.168.1.9/24
>               - 10.0.10.9/24
>            gateway4: 192.168.1.1
>            nameservers:
>               search:
>                 - lan
>               addresses:
>                 - 10.0.10.15
>                 - 10.0.10.10
>
>
> FWIW I've tried to match on MAC address - it would be nice because I
> could have one configuration file that I could deploy to all systems
> instead of needing to customize them, but I haven't been able to get them
> to work. Here's one attempt:
>
>   wifis:
>     wlx9cefd5fcd82b:
>       match:
>         name: wlx9cefd5fcd82b
>        macaddress: "9c:ef:d5:fc:d8:2b"
>
> but I don't recall what had as the name . (That's the system's device
> name based on the MAC address.) Hmm... maybe I should have tried 'all-wans'.
>
> Bear
>
> On Thu, May 20, 2021 at 9:54 AM Zan Lynx < zlynx at acm.org> wrote:
>
> On 5/20/21 8:34 AM, D. Stimits wrote:
> > Does anyone here know how to force my Ubuntu 18.04 to completely
> > leave out a default route for my private router? Or to permanently
> > set that route to a low priority, or to permanently set my public
> > interface to metric of 1?
>
> You must be using DHCP or this would not apply.
>
> Change your DHCP on your private network so that it does not apply any
> default route. Then each DHCP client will only have routes to the
> networks controlled by the private router.
>
> --
>                  Knowledge is Power -- Power Corrupts
>                          Study Hard -- Be Evil
>
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