2

Am trying to add a script which will get executed on DHCP ip change for a particular interface. for that I have copied the below script at "/etc/dhcp/dhclient.d/dhcp-hook.sh". I need to get router IP whenever dhcp renew/bound happens in order to add route via that ip. Can someone suggest how do I get router ip info in "dhcp4-change" event, $DHCP4_routers_IP_ADDRESS in the below case. The script looks like below, table uplink1 is already populated. Just need to know how to get the router ip.

  1 #! /bin/sh
  2 
  3 interface=$1 status=$2
  4 
  5 if [ "$status" != "dhcp4-change"  -o
  6      $interface != $UPLINK1 ]; then
  7    return
  8 fi
  9 if  [ $interface = $UPLINK1 ]; then
 10     if [ -n $DHCP4_routers_IP_ADDRESS ]; then
 11        ip route add default via $DHCP4_routers_IP_ADDRESS table uplink1
 12     fi
 13 fi
0

You could always add echo "$(env)" > change_env.log and trigger the event to see what the environment variables look like then you could hopefully find what you need. A few promising environment variables from a different event include DHCP4_DHCP_SERVER_IDENTIFIER, IP4_GATEWAY, IP4_NAMESERVERS, DHCP4_DOMAIN_NAME_SERVERS.

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