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Re: debian 8.2 live "standard" install - how to set up wifi?



On Sat, 28 Nov 2015 12:36:35 +0000, Brian <ad44@cityscape.co.uk> wrote:

> On Sat 28 Nov 2015 at 10:52:46 +0300, moxalt wrote:
> 
> > On Fri, 27 Nov 2015 19:58:46 +0000, Brian <ad44@cityscape.co.uk> wrote:
> > 
> > > This bothers me. You install without any tasks (that's ok) and
> > > networking is there when the new systam boots? Are you installing over a
> > > wireless link? Just to emphasise - no wired connection is present.
> > 
> > Yes, networking is just there.
> 
> This still bothers me. :)
> 
> If networking is just there why, as you say later, do you have to bring
> wlan0 up? Also, how do you manage to have eth0 in the output of
> 'ifconfig' when the wireless interface has been chosen for installing?
> It cannot be in /etc/network/interfaces.

Let me clarify what I meant by networking just being there. I did not say that
a connection would be up and running straight away- just that all relevant
network interfaces would be available for me to connect over. It is not the
case that I am able to use internet straight away after booting- I have to
actually connect to things with tools like wpa_supplicant, iwconfig, etc.

By the way, it seems I've been putting wlan0 up needlessly this whole time. I
taught myself how to do command-line networking off some Ubuntu tutorial that
said I should do it (probably just to cover all cases) and have been doing
ifconfig <interface> up this whole time for no reason. After reading the
ifconfig man page, it seems the kernel uses ifconfig to put all interfaces up
at boot anyway, after which they are all up (as indicated by ifconfig run with
no arguments).

What is strange, though, is that when I boot using the 'text'
LINUX_CMDLINE_DEFAULT GRUB kernel parameter, and then type ifconfig wlan0 up in
the tty, a dmesg message appears declaring 'Link not ready' or something to
that effect- and then it goes on working just fine. Does anyone else see this
happening?

After I investigated, your second point sent shivers of spooky down my spleen.
The contents of /etc/network/interfaces are as follows:

-------------------------------------------------------------------------------
# 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
-------------------------------------------------------------------------------

Neither eth nor wlan are there!? You were right when you said they couldn't be
in /etc/network/interfaces. However, the mystery continues- ifconfig reports
the following:

-------------------------------------------------------------------------------
eth0      Link encap:Ethernet  HWaddr f4:6d:04:89:e3:01  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

wlan0     Link encap:Ethernet  HWaddr e0:b9:a5:22:b9:43  
          inet addr:192.168.1.109  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::e2b9:a5ff:fe22:b943/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6373 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2862 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:4755201 (4.5 MiB)  TX bytes:400106 (390.7 KiB)
------------------------------------------------------------------------------

lo, wlan0, and eth0 are all there! I am but a humble luser, and have no idea
what is going on.

> > I boot with a netinstall USB, select my wireless interface for the
> > installation, and networking just works after I've rebooted. Both eth0,
> > wlan0, and lo appear in my ifconfig list. The firmware is correctly
> > installed and everything works. All that remains is to put wlan0 up,
> > connect to my router with wpa_supplicant, and get an IP with dhclient.
> > After that, I'm good to go.
> 
> I'd better say why I am bothered.
> 
> D-I sets up networking with netcfg. The file
> 
>   /usr/lib/finish-install.d/55netcfg-copy-config
> 
> in the package has
> 
>   # Check for preseeding. If the value of the question is empty then set
>   # default options. Document automatic selection changes in the template.
>   if [ -z "$RET" ]; then
>           if $NM_IS_INSTALLED; then
>                  db_set netcfg/target_network_config $CONFIG_NM
>           else
>                  if [ "$NETCFG_CONNECTION_TYPE" = "wired" ]; then
>                          db_set netcfg/target_network_config
> $CONFIG_INTERFACES else # wireless
>                          db_set netcfg/target_network_config $CONFIG_LOOPBACK
>                  fi
>           fi
> fi
> 
> If NM is not installed (which is what would happen with no tasks) and no
> wired install the only stanza written to /e/n/i at the end of the
> install is a loopback one. That is, metworking is not there after first
> boot.

My installation appears to have thus defied the laws of physics, Debian
installation, and bash scripting.

I installed a completely minimal setup with no tasks selected, using wlan0 as
my installation network interface. Lo and behold, upon boot everything works as
described.

Can someone else try installing like I did and see if the same occurs?


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