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Bug#694068: netcfg: Wireless connectivity present during an install but absent afterwards

On Tue 06 Mar 2018 at 11:07:59 +1100, Trent W. Buck wrote:

> Brian Potkin wrote:
> > The number of users affected by this issue over the years is not
> > insignificant. Not a single one has written in support of the
> > situation.
> This issue has bitten me at least twice so far.
> This issue's history seems to be bogged down on whether interfaces(5)
> can be mode 0600 (to hide the cleartext passphrase).
> This is not necessary; the passphrase can go in a separate file.

Mode 0600 wasn't intially given as a reason:


 > I realise a default is only a default and the selection can be changed,
 > but I'm puzzled by the third option. Why treat a wireless install
 > differently from a wired install? It would expected that a user who has
 > chosen not to use a wired connection would still want connectivity after
 > booting into into the new system,

   The main reason for this is that as far as I know writing configs
   related to a wireless network to /e/n/i enforce using only that
   particular network later (of course if you don't modify the file) and
   also that the interface is unmanageable for other tools. The idea was
   to leave the network unconfigured, so that it can be managed later
   (perhaps via something else than NM).

Later in the thread:


 > On the other hand, we have users who chose not to install a desktop
 > environment but want their machine to migrate between networks when it's
 > moved. These users are going to need to do some form of sysadmin work
 > post-install, whether it's installing a desktop environment and wicd, or
 > editing /etc/network/interfaces on each fresh network, or bringing up
 > wifi connections by hand. So I can't see locking a default into
 > /etc/network/interfaces causing them much bother.

   IIRC we decided on this default before we added the code to change the
   access mode of /e/n/i if it contains a password. The main reason for
   defaulting to no configuration in this case was to avoid having
   passwords in there. If people think it should default to ifupdown in
   this case this can be changed.

The default (loopback only for wireless) was added without considering
mode 0600. At this stage in the history there appears to be a willingness
to use ifupdown and not loopback.

> Here is a minimal config, assuming WPA2 PSK (not Enterprise) and DHCP (not static) for all SSIDs:
>     cat >/etc/network/interfaces <<EOF
>     allow-auto lo $iface
>     iface lo inet loopback
>     iface default inet dhcp
>     iface $iface inet manual
>       wpa-roam /etc/wpa_supplicant/wpa_supplicant-$iface.conf
>     EOF
>     wpa_passphrase "$ssid" "$passphrase" >"/etc/wpa_supplicant/wpa_supplicant-$iface.conf"
>     chmod 0600 "/etc/wpa_supplicant/wpa_supplicant-$iface.conf"
> If you don't want to udebify wpa_passphrase, you can do it by hand:
>     cat >"/etc/wpa_supplicant/wpa_supplicant-$iface.conf" <<EOF
>     network={
>       ssid="$ssid"
>       psk="$passphrase"
>     }
>     EOF
> If you really hate ifupdown, you can use systemd instead (not fully tested):
>     cat >/etc/systemd/network/$iface.network <<EOF
>     [Match]
>     iface=$iface
>     [Network]
>     DHCP=yes
>     EOF
>     systemctl enable wpa_supplicant@$iface.service
>     wpa_passphrase "$ssid" "$passphrase" >"/etc/wpa_supplicant/wpa_supplicant-$iface.conf"
>     chmod 0600 "/etc/wpa_supplicant/wpa_supplicant-$iface.conf"
> If even these things are too much, can you AT LEAST install
> wpasupplicant?  Writing config files is much easier than ferrying
> .debs between computers by USB key.
> If this bug is going to be kept ANOTHER Debian release, can you at
> least warn people about it in the buster Installation Guide?

Or dispense with loopback for an installation over wireless (an easy
enough change) and warn about 0600 in the Release Notes.


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