loopback doesn't come up correctly on boot

[ultralame]

EDIT: Moving this post to Ubuntu. Now I think it's distro-centric. Sorry.


Running Ubuntu 6.06 Universe (I know, but this looks like a non-specific problem).

When my machine reboots, the lo interface is not configured correctly. I can manually fix it easily, but do not understand why it would have this problem. I have already searched the Ubuntu forums and have not found any answer.

After booting into runlevel 2 (default):

#ifconfig:

eth0 Link encap:Ethernet HWaddr XX:XX:XX:XX:XX:XX
inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: xxxx:xxxxxxxxxxx/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:26448 errors:0 dropped:0 overruns:0 frame:0
TX packets:28757 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4561028 (4.3 MiB) TX bytes:15015965 (14.3 MiB)
Interrupt:201 Base address:0xc000

#ifconfig lo

o Link encap:Local Loopback
LOOPBACK MTU:16436 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)

Note: it's missing the 'inet addr' line.

#ifup -v lo

ifup: interface lo already configured

Then I run 'ifdown lo', and run ifup again:
#ifup -v lo

Configuring interface lo=lo (inet)
run-parts --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
ifconfig lo 127.0.0.1 up
run-parts --verbose /etc/network/if-up.d
run-parts: executing /etc/network/if-up.d/mountnfs
run-parts: executing /etc/network/if-up.d/ntpdate
run-parts: executing /etc/network/if-up.d/postfix

And after running that last command, I get this:
#ifconfig lo

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:16436 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)

At this point, things are working (although I have to restart some services for them to bind correctly to localhost).

/etc/network/interfaces:

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
address 192.168.1.10
netmask 255.255.255.0
gateway 192.168.1.254

I also checked the /etc/network/*.d scripts- all of them exit when asked to operate on lo.


Here's the startup scripts:
/etc/rcS.d/S08loopback ->../init.d/loopback

#!/bin/sh -e
#
# loopback - brings up the loopback (127.0.0.1) network device so that
# DHCP and other such things will work
#

# Check the package is still installed
[ -x /sbin/ifup ] || exit 0

# Get LSB functions
. /lib/lsb/init-functions
. /etc/default/rcS

case "$1" in
start)
[ -d /var/run/network ] || mkdir /var/run/network

log_begin_msg "Starting basic networking..."
if ifup -v --allow auto lo; then
log_end_msg 0
else
log_end_msg $?
fi
;;
stop)
log_begin_msg "Stopping basic networking..."
if ifdown lo; then
log_end_msg 0
else
log_end_msg $?
fi
;;
restart|force-reload)
exit 0
;;
*)
echo "Usage: /etc/init.d/loopback {start|stop|restart|force-reload}"
exit 1
;;
esac

exit 0

/etc/rcS.d/S40networking -> ../init.d/networking

#!/bin/sh -e
### BEGIN INIT INFO
# Provides: networking
# Required-Start: mountvirtfs ifupdown $local_fs
# Default-Start: S
# Default-Stop: 0 6
### END INIT INFO

PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin"

[ -x /sbin/ifup ] || exit 0

. /lib/lsb/init-functions


case "$1" in
start)
log_action_begin_msg "Configuring network interfaces"
type usplash_write >/dev/null 2>/dev/null && usplash_write "TIMEOUT 120" || true
if [ "$VERBOSE" != no ]; then
if ifup -a; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
else
if ifup -a >/dev/null 2>&1; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
fi
type usplash_write >/dev/null 2>/dev/null && usplash_write "TIMEOUT 15" || true
;;

stop)
if sed -n 's/^[^ ]* \([^ ]*\) \([^ ]*\) .*$/\2/p' /proc/mounts |
grep -qE '^(nfs[1234]?|smbfs|ncp|ncpfs|coda|cifs)$'; then
log_warning_msg "not deconfiguring network interfaces: network shares still mounted."
exit 0
fi

log_action_begin_msg "Deconfiguring network interfaces"
if [ "$VERBOSE" != no ]; then
if ifdown -a --exclude=lo; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
else
if ifdown -a --exclude=lo >/dev/null 2>/dev/null; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
fi
;;

force-reload|restart)
log_action_begin_msg "Reconfiguring network interfaces"
ifdown -a --exclude=lo || true
if ifup -a --exclude=lo; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
;;

*)
echo "Usage: /etc/init.d/networking {start|stop|restart|force-reload}"
exit 1
;;
esac

exit 0

Any ideas? I have seen some posts that contain the following additional lines in their interfaces file:

# The loopback network interface
auto lo
iface lo inet loopback
address 127.0.0.1
netmask 255.0.0.0

I have also been told to try addding:

mapping hotplug

script grep
map lo

but I think that would require installing a hotplug module/service, and I would rather figure out what's wrong now.

Last question- is there a way, other than changing what's in rcS.d, to boot into single-user mode, run scripts manually, and check to see which one, if any, is screwing up the interface?

Thanks!

[chipcastle]

I had this same problem and have fixed it.

In my situation, I noticed upon bootup that there was a message about '/var/run/network'. I cannot remember if it said it didn't exist or if it couldn't create it. Seems strange to me since /etc/init.d/networking runs as root and should be able to determine if the directory exists, and if not, create it.

At any rate, I created it manually:
sudo mkdir /var/run/network

I noticed subsequent bootups were very slow when attempting to setup the network interfaces. After it finished bootup, a file called /var/run/network/ifstate now existed. Attempting to restart the network interfaces with "sudo /etc/init.d/network restart" did nothing to help the loopback device. However, strangely enough, after removing the file with "sudo rm /var/run/network/ifstate" and then restarting the network, all is well.

Maybe this was an isolated issue on my workstation, but I thought I would pass it along in case others are having the same issue. It seems to me that it is a bug in the network interface script(s) and possibly the package needs to be updated in the debian sources.

[ultralame]

My system has the /var/run/network folder, and it does contain the ifstate file.

But I am not sure that file is the problem:
$ cat /var/run/network/ifstate
lo=lo
eth0=eth0
eth0:0=eth0:0

This looks right to me.