[lug] Ubuntu 18.04 Route Metric
John Hernandez
jph at jph.net
Fri May 21 10:56:00 MDT 2021
It occurs to me that you could also switch from DHCP-client to a static
configuration for the LAN interface on your Ubuntu server, whilst leaving
the public interface configured as DHCP-client. If you want to be thorough
about it, you could also remove your statically assigned IP address from
the Private LAN DHCP server's address pool.
On Fri, May 21, 2021 at 10:51 AM D. Stimits <stimits at comcast.net> wrote:
>
>
> On 05/21/2021 10:29 AM John Hernandez <jph at jph.net> wrote:
>
>
> 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.
>
> I wish I could :(
>
> I will look closer at the router and see if there is any way to disable
> that.
>
> 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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