#!/bin/bash # This script came from ubnt.com forum user "bradd" in the following post # http://community.ubnt.com/t5/EdgeMAX/Automatic-DNS-resolution-of-DHCP-client-names/td-p/651311 # It has been modified by Ubiquiti to update the /etc/host file # instead of adding to the CLI. # Thanks to forum user "itsmarcos" for bug fix & improvements # Thanks to forum user "ruudboon" for multiple domain fix # Thanks to forum user "chibby85" for expire patch and static-mapping if [ $# -lt 5 ]; then echo Invalid args logger -s -t on-dhcp-event "Invalid args \"$@\"" exit 1 fi action=$1 client_name=$2 client_ip=$3 client_mac=$4 domain=$5 file=/etc/hosts changes=0 if [ -z "$client_name" ]; then logger -s -t on-dhcp-event "Client name was empty, using MAC \"$client_mac\" instead" client_name=$(echo "client-"$client_mac | tr : -) fi if [ "$domain" == "..YYZ!" ]; then client_fqdn_name=$client_name client_search_expr=$client_name else client_fqdn_name=$client_name.$domain client_search_expr="$client_name\\.$domain" fi case "$action" in commit) # add mapping for new lease echo "- new lease event, setting static mapping for host "\ "$client_fqdn_name (MAC=$client_mac, IP=$client_ip)" # # grep fails miserably with \t in the search expression. # In the following line one <Ctrl-V> <TAB> is used after $client_search_expr # followed by a single space grep -q " $client_search_expr #on-dhcp-event " $file if [ $? == 0 ]; then echo pattern found, removing wc1=`cat $file | wc -l` sudo sed -i "/ $client_search_expr\t #on-dhcp-event /d" $file wc2=`cat $file | wc -l` if [ "$wc1" -eq "$wc2" ]; then echo No change fi else echo pattern NOT found fi # check if hostname already exists (e.g. a static host mapping) # if so don't overwrite grep -q " $client_search_expr " $file if [ $? == 0 ]; then echo host $client_fqdn_name already exists, exiting exit 1 fi line="$client_ip\t $client_fqdn_name\t #on-dhcp-event $client_mac" sudo sh -c "echo -e '$line' >> $file" ((changes++)) echo Entry was added ;; release) # delete mapping for released address echo "- lease release event, deleting static mapping for host $client_fqdn_name" wc1=`cat $file | wc -l` sudo sed -i "/ $client_search_expr\t #on-dhcp-event /d" $file wc2=`cat $file | wc -l` if [ "$wc1" -eq "$wc2" ]; then echo No change else echo Entry was removed ((changes++)) fi ;; *) logger -s -t on-dhcp-event "Invalid command \"$1\"" exit 1; ;; esac if [ $changes -gt 0 ]; then echo Success pid=`pgrep pdns_recursor` if [ -n "$pid" ]; then sudo rec_control reload-zones fi else echo No changes made fi exit 0