[Bug 1390777] [NEW] Existing default gateway causes to fail to bring fully up a device

Sat Nov 8 18:22:55 UTC 2014

Public bug reported:

I'm using Ubuntu 15.04 dev with ifupdown 0.7.48.1ubuntu5. My network
contains a router which is able to handle connections over LAN and WLAN
but if a client is configured to have this router as gateway on his
ethernet and WLAN device the second device which is brought up causes an
error on ifup. Here is such a client setup from /etc/network/interfaces
(the wpa-psk is replaced with asterisks):

# 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
auto lo
iface lo inet loopback

# The primary network interface
#auto eth0
iface eth0 inet static
	address 192.168.1.3
	dns-nameservers 192.168.1.1
	gateway 192.168.1.1
	netmask 255.255.255.0

#auto wlan0
iface wlan0 inet static
	address 192.168.1.4
	dns-nameservers 192.168.1.1
	gateway 192.168.1.1
	netmask 255.255.255.0
	wpa-psk ***
	wpa-ssid o2-WLAN65

Bringing up these devices manually results in this output:

root at ubuntu:~# ip route
root at ubuntu:~# ifup -v eth0
Configuring interface eth0=eth0 (inet)
run-parts --exit-on-error --verbose /etc/network/if-pre-up.d
run-parts: executing /etc/network/if-pre-up.d/wireless-tools
run-parts: executing /etc/network/if-pre-up.d/wpasupplicant
ip addr add 192.168.1.3/255.255.255.0 broadcast 192.168.1.255 	  dev eth0 label eth0
ip link set dev eth0   up
 ip route add default via 192.168.1.1  dev eth0 
run-parts --exit-on-error --verbose /etc/network/if-up.d
run-parts: executing /etc/network/if-up.d/000resolvconf
run-parts: executing /etc/network/if-up.d/upstart
run-parts: executing /etc/network/if-up.d/wpasupplicant
root at ubuntu:~# ip route
default via 192.168.1.1 dev eth0 
192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.3 
root at ubuntu:~# ifup -v wlan0
Configuring interface wlan0=wlan0 (inet)
run-parts --exit-on-error --verbose /etc/network/if-pre-up.d
run-parts: executing /etc/network/if-pre-up.d/wireless-tools
run-parts: executing /etc/network/if-pre-up.d/wpasupplicant
wpa_supplicant: wpa-driver nl80211,wext (default)
wpa_supplicant: /sbin/wpa_supplicant -s -B -P /var/run/wpa_supplicant.wlan0.pid -i wlan0 -D nl80211,wext -C /var/run/wpa_supplicant
Starting /sbin/wpa_supplicant...
wpa_supplicant: waiting for "/var/run/wpa_supplicant.wlan0.pid":  0 (max. 5)
wpa_supplicant: creating sendsigs omission pidfile: /run/sendsigs.omit.d/wpasupplicant.wpa_supplicant.wlan0.pid
wpa_supplicant: ctrl_interface socket located at /var/run/wpa_supplicant/wlan0
wpa_supplicant: configuring network block -- 0
wpa_supplicant: wpa-ssid "o2-WLAN65" -- OK
wpa_supplicant: wpa-psk ***** -- OK
wpa_supplicant: enabling network block 0 -- OK
ip addr add 192.168.1.4/255.255.255.0 broadcast 192.168.1.255 	  dev wlan0 label wlan0
ip link set dev wlan0   up
 ip route add default via 192.168.1.1  dev wlan0 
RTNETLINK answers: File exists
Failed to bring up wlan0.

ifup calls "ip route" to setup the default gateway for wlan0 but fails because it already exists for eth0. Maybe ifup should check if a default gateway already exists and not call "ip route" in such a case.

** Affects: ifupdown (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1390777

Title:
  Existing default gateway causes to fail to bring fully up a device

Status in “ifupdown” package in Ubuntu:
  New

Bug description:
  I'm using Ubuntu 15.04 dev with ifupdown 0.7.48.1ubuntu5. My network
  contains a router which is able to handle connections over LAN and
  WLAN but if a client is configured to have this router as gateway on
  his ethernet and WLAN device the second device which is brought up
  causes an error on ifup. Here is such a client setup from
  /etc/network/interfaces (the wpa-psk is replaced with asterisks):

  # 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
  auto lo
  iface lo inet loopback

  # The primary network interface
  #auto eth0
  iface eth0 inet static
  	address 192.168.1.3
  	dns-nameservers 192.168.1.1
  	gateway 192.168.1.1
  	netmask 255.255.255.0

  #auto wlan0
  iface wlan0 inet static
  	address 192.168.1.4
  	dns-nameservers 192.168.1.1
  	gateway 192.168.1.1
  	netmask 255.255.255.0
  	wpa-psk ***
  	wpa-ssid o2-WLAN65

  Bringing up these devices manually results in this output:

  root at ubuntu:~# ip route
  root at ubuntu:~# ifup -v eth0
  Configuring interface eth0=eth0 (inet)
  run-parts --exit-on-error --verbose /etc/network/if-pre-up.d
  run-parts: executing /etc/network/if-pre-up.d/wireless-tools
  run-parts: executing /etc/network/if-pre-up.d/wpasupplicant
  ip addr add 192.168.1.3/255.255.255.0 broadcast 192.168.1.255 	  dev eth0 label eth0
  ip link set dev eth0   up
   ip route add default via 192.168.1.1  dev eth0 
  run-parts --exit-on-error --verbose /etc/network/if-up.d
  run-parts: executing /etc/network/if-up.d/000resolvconf
  run-parts: executing /etc/network/if-up.d/upstart
  run-parts: executing /etc/network/if-up.d/wpasupplicant
  root at ubuntu:~# ip route
  default via 192.168.1.1 dev eth0 
  192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.3 
  root at ubuntu:~# ifup -v wlan0
  Configuring interface wlan0=wlan0 (inet)
  run-parts --exit-on-error --verbose /etc/network/if-pre-up.d
  run-parts: executing /etc/network/if-pre-up.d/wireless-tools
  run-parts: executing /etc/network/if-pre-up.d/wpasupplicant
  wpa_supplicant: wpa-driver nl80211,wext (default)
  wpa_supplicant: /sbin/wpa_supplicant -s -B -P /var/run/wpa_supplicant.wlan0.pid -i wlan0 -D nl80211,wext -C /var/run/wpa_supplicant
  Starting /sbin/wpa_supplicant...
  wpa_supplicant: waiting for "/var/run/wpa_supplicant.wlan0.pid":  0 (max. 5)
  wpa_supplicant: creating sendsigs omission pidfile: /run/sendsigs.omit.d/wpasupplicant.wpa_supplicant.wlan0.pid
  wpa_supplicant: ctrl_interface socket located at /var/run/wpa_supplicant/wlan0
  wpa_supplicant: configuring network block -- 0
  wpa_supplicant: wpa-ssid "o2-WLAN65" -- OK
  wpa_supplicant: wpa-psk ***** -- OK
  wpa_supplicant: enabling network block 0 -- OK
  ip addr add 192.168.1.4/255.255.255.0 broadcast 192.168.1.255 	  dev wlan0 label wlan0
  ip link set dev wlan0   up
   ip route add default via 192.168.1.1  dev wlan0 
  RTNETLINK answers: File exists
  Failed to bring up wlan0.

  ifup calls "ip route" to setup the default gateway for wlan0 but fails because it already exists for eth0. Maybe ifup should check if a default gateway already exists and not call "ip route" in such a case.

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