Re: How to set network connection priority

[Dan Williams <dcbw redhat com>]

On Fri, 2019-07-26 at 21:52 +0530, Mohammed Sadiq wrote:
> Hi,
>
> Is it possible to set IP routing (and DNS) priority when multiple
> network is present?  Say like, “Connection A” to have lower priority
> over every other connection, and “Connection B” having more priority
> than “Connection A”, but less priority than every other connection.
> So if there is ever a connection other than ‘A’ or ‘B’, that
> connection
> will be used for IP (and DNS) routing, otherwise “Connection B” will
> be
> used, and otherwise, “Connection A.”

The ipv4 setting for each connection has a "dns-priority" property that
you can use to set a given connection's DNS servers as lower priority.
It also has a "route-metric" property that will do the same for routes
(but has a different scale based on kernel routing metrics).

man nm-settings

has a lot of info about these values.

nmcli con mod "my connection name" ipv4.dns-priority X

By default every connection gets the same priority (0). The larger the
number, the less-preferred the connection. So in your example, you
could set:

nmcli con mod "Connection A" ipv4.dns-priority 10 ipv4.route-metric 1050
nmcli con mod "Connection B" ipv4.dns-priority 5 ipv4.route-metric 1040

And that may do what you want.

Dan

> I'm wring a C code (that will hopefully be into gnome-control-
> center),
> so I would be okay with solutions that are possible via code only, or
> just configuration changes for NMSetting.
>
>
> Thanks,
> Mohammed Sadiq
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