IPv6 Troubleshooting Notes for IPv6 on AWS

crontab

* *	* * *	root /bin/bash -x /usr/local/bin/recuperate.sh >> /tmp/recuperate.out 2>&1

recuperate.sh

#!/bin/bash -x
#
LOCK_FILE=/tmp/recuperate.lock

if [ -f $LOCK_FILE ] && [ -f "/proc/$(cat $LOCK_FILE)" ]; then
  echo "bailing, already running"
fi

echo $$ > $LOCK_FILE
date # record timestamps
if ps auxwww | grep dhclient | grep -v grep; then
  # dhclient is running, network should be up...
  if ! ping -c 2 10.0.0.6; then
    if ! ping -c 2 8.8.8.8; then
      # ... but it's not up, it's down, probably dhclient is stuck
      killall -9 dhclient # kill it with fire
      mv /etc/network/interfaces{,.$$}
      cat > /etc/network/interfaces << EOF
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet dhcp
iface eth0 inet6 dhcp
EOF
    fi
  fi
  ifup eth0
fi

rm $LOCK_FILE