Script on NIC Up

Quantumstate · 01-15-2012, 08:46 AM

Does anyone know why execution of a script when a network interface comes up, doesn't work?

I have this in /etc/network/if-up.d

Code:

#!/bin/sh

# Don't run sshcygnus while bringing up the loopback or eth0 device;
# it's not necessary until we bring up wlan0
[ "$IFACE" = "lo" ] || exit 0
[ "$IFACE" = "eth0" ] || exit 0
echo "sshcygnus0" >/var/log/messages

if [ -x /usr/local/bin/sshcygnus ] ; then
echo "sshcygnus1" >/var/log/messages
  exec /usr/local/bin/sshcygnus
echo "sshcygnus2" >/var/log/messages

fi

corp769 · 01-15-2012, 12:36 PM

What distro are you using? I use Fedora 15, and this is how my system is setup:

Code:

[root@ltp01 network-scripts]# pwd
/etc/sysconfig/network-scripts
[root@ltp01 network-scripts]# ls -a
.                     ifcfg-em1              ifdown       ifdown-ipsec  ifdown-ppp     ifup          ifup-ippp   ifup-isdn   ifup-ppp     ifup-wireless        keys-wrt350nmodv101a
..                    ifcfg-lo               ifdown-bnep  ifdown-ipv6   ifdown-routes  ifup-aliases  ifup-ipsec  ifup-plip   ifup-routes  init.ipv6-global     net.hotplug
ifcfg-DJRcomputing    ifcfg-wlan0            ifdown-eth   ifdown-isdn   ifdown-sit     ifup-bnep     ifup-ipv6   ifup-plusb  ifup-sit     keys-DJRcomputing    network-functions
ifcfg-donna-wireless  ifcfg-wrt350nmodv101a  ifdown-ippp  ifdown-post   ifdown-tunnel  ifup-eth      ifup-ipx    ifup-post   ifup-tunnel  keys-donna-wireless  network-functions-ipv6
[root@ltp01 network-scripts]#

Quantumstate · 01-19-2012, 10:23 AM

Using Debian. Unfortunately Fedora is quite different.

After more testing, it appears that these two lines are at fault:
[ "$IFACE" = "lo" ] || exit 0
[ "$IFACE" = "eth0" ] || exit 0

When I comment them out, the script then runs.

It doesn't make sense, as the script is run for each interface. When I shut down wlan0 and bring it back up, lo and eth0 are not being brought up. wlan0 should be the interface in $IFACE.

Also, when running it tries to set up reverse tunnels for IPP (port 631) but fails with 'no route to host'. Only subsequent tunnels show the normal setup, including MythTV, Squid, and MySQL. I guess this is because of the delay in association of the wlan interface with the router, although I put a wait 3 at the beginning of the tunnel script and it didn't help. So it's a mystery...