Log parsing utils in contrib/reverse-dns

contrib/reverse-dns/reverse_dns.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+# $Id: reverse_dns.sh 4 2015-02-17 20:14:59Z jo $
+#
+# Usage: reverse_dns.sh IP
+# Uses the dnsmasq query log to lookup the name 
+# that was last queried to return the given IP.
+#
+
+IP=$1
+qmIP=`echo $IP | sed 's#\.#\\.#g'`
+LOG=/var/log/dnsmasq.log
+
+IP_regex='^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$'
+
+if ! [[ $IP =~ $IP_regex ]]; then
+  echo -n $IP
+  exit
+fi
+
+NAME=`tac $LOG | \
+  grep " is $IP" | head -1 | \
+  sed "s#.* \([^ ]*\) is $qmIP.*#\1#" `
+
+if [ -z "$NAME" ]; then
+  echo -n $IP
+else
+  echo -n $NAME
+fi
+