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Re: connecting to two networks simultaneously on buster




On Tue, Aug 21, 2018 at 11:08:10PM +0100, Eric S Fraga wrote:
> On Tuesday, 21 Aug 2018 at 16:58, Glenn English wrote:
> > On Tue, Aug 21, 2018 at 3:39 PM Eric S Fraga <e.fraga@xxxxxxxxx> wrote:
> >
> >> Would somebody please point me to the right magical incantation that
> >> would allow my desktop computer to have both connections active
> >> simultaneously?
> >
> > I've done that on a couple boxes here -- a laptop (WiFi and an
> > Ethernet) and a workstation (2 Ethernets)
> >
> > On both of them, I wrote a /etc/network/interfaces script to give an
> > IP to the Ethernet and start at boot. The others are DHCP and don't
> > come on at boot.
> 
> Thanks.  I added a few lines to /e/n/i and everything works just fine
> now.  The actual lines are
> 
> ,----
> | # the USB network for my Gemini
> | auto enp0s29u1u1
> | iface enp0s29u1u1 inet static
> |   address 10.15.19.80
> `----
> 
> and I simply "sudo ifup enp0s29u1u1" when I need it.
> 
> But I still do not understand why it works automatically on one of the
> systems but not the other.  One of those mysteries, I guess.

Static configuration is by necessity (basically) custom setup - i.e.
requires manual intervention.

Automatic means the above /e/n/i lines would look like this instead:

# the USB network for my Gemini
auto enp0s29u1u1
iface enp0s29u1u1 inet dhcp


But of course for network-manager, it would by default use dhcp, and
you would not manually configure for DHCP in your /e/n/i file.

Always remember you can do an in-foreground one shot DHCP like so:

sudo dhclient -d enp0s29u1u1

which has the benefit that you can easily kill it as desired with a
CTRL-c, AND you can monitor its output immediately, AND you will see
immediately if you got the device/ interface name wrong. What's not
to like?

Good luck,