Worked example, was Re: Still unable to restart networking on Debian 9 text mode only
- Date: Sat, 24 Nov 2018 20:05:54 -0600
- From: David Wright <deblis@xxxxxxxxxxxxxxxxx>
- Subject: Worked example, was Re: Still unable to restart networking on Debian 9 text mode only
On Sat 24 Nov 2018 at 12:25:20 (-0500), Gary Dale wrote:
> On 2018-11-23 8:25 a.m., Luciano Andress Martini wrote:
> > Additional information - Again Debian 9.6 Fresh Install without
> > graphical interface:
> > cat /etc/network/interfaces:
> > # This file describes the network interfaces available on your system
> > # and how to activate them. For more information, see interfaces(5).
> > source /etc/network/interfaces.d/*
> > # The loopback network interface
> > auto lo
> > iface lo inet loopback
> > # The primary network interface
> > allow-hotplug enp0s3
> > iface enp0s3 inet static
> > address 10.5.0.2/24
> > gateway 10.5.0.1
> > # dns-* options are implemented by the resolvconf package, if installed
> > dns-nameservers 188.8.131.52
> > dns-search neoconsig.local
> > Just changed 10.5.0.2 to 10.5.0.3
> > #ifdown enp0s3
> > #ifup enp0s3
> Reco has already explained why this approach is incorrect.
The OP seems to prefer imagining a bug rather than taking much notice
of the replies.
> My own two cents on the problem is that Interfaces is meant to define
> how the network is brought up, not to change a running network.
Yes, but it also appears that interfaces also defines how the network
is brought down again, which is what the OP doesn't understand.
> If you
> want to change a running network, use ifconfig or ip to change the
> address. e.g. ifconfig enp-s3 10.5.0.3 should work since all you are
> changing is the ip address.
I can't see any advantage in this as you have to do all the grunt work
yourself instead of letting ifdown/ifup do it for you. For example:
Here's my normal /e/n/i:
$ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
iface lo inet loopback
# The primary network interface
iface enp0s14 inet dhcp
I set up two static alternatives, one using the same address (13) as I
get from the router, and one wacky one (213) in the "intruder" range:
iface enp0s14 inet static
iface enp0s14 inet static
(the rest of each file is unchanged from the normal one).
Running a script like:
cp /etc/network/interfaces-static-213 /etc/network/interfaces
releases the lease, downs the avahi-daemon, changes the network
address, restarts the ssh server, reconfigures ntpd, and ups the
avahi-daemon. My ssh session also goes dead (as I was logged in
Logging in on 192.168.1.213 instead (and avoiding polluting my
known_hosts file) I can now run a similar script to the above,
that has the line
cp /etc/network/interfaces-static-13 /etc/network/interfaces
cp /etc/network/interfaces-normal-dhcp /etc/network/interfaces
in it, and my old ssh session comes alive again (the new session
going dead of course). The logs show all the other changes being
reversed back to normal, with a new lease etc.
So you can see the extra work (worth more than two cents) that
the higher level commands do for you automatically, thanks to