New version of contrib/reverse-dns

contrib/reverse-dns/README

@@ -1,18 +1,18 @@
-Hi.
+The script reads stdin and replaces all IP addresses with names before
+outputting it again. IPs from private networks are reverse looked  up
+via dns. Other IP adresses are searched for in the dnsmasq query log.
+This gives names (CNAMEs if I understand DNS correctly) that are closer
+to the name the client originally asked for then the names obtained by
+reverse lookup. Just run
 
-To translate my routers netstat-nat output into names that actually talk
+netstat -n -4 | ./reverse_replace.sh 
-to me I have started writing to simple shell scripts. They require 
+
+to see what it does. It needs 
 
 log-queries
 log-facility=/var/log/dnsmasq.log
 
-to be set. With
+in the dnsmasq configuration.
-
-netstat-nat -n -4 | reverse_replace.sh 
-
-I get retranslated output.
-
-Sincerely,
-Joachim
 
+The script runs on debian (with ash installed) and on busybox.
 

contrib/reverse-dns/reverse_dns.sh

@@ -1,29 +0,0 @@
-#!/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
-

contrib/reverse-dns/reverse_replace.sh

@@ -1,28 +1,125 @@
-#!/bin/bash
+#!/bin/ash
-# $Id: reverse_replace.sh 4 2015-02-17 20:14:59Z jo $
+# $Id: reverse_replace.sh 18 2015-03-01 16:12:35Z jo $
 #
 # Usage e.g.: netstat -n -4 | reverse_replace.sh 
 # Parses stdin for IP4 addresses and replaces them 
-# with names retrieved by reverse_dns.sh
+# with names retrieved by parsing the dnsmasq log.
+# This currently only gives CNAMEs. But these 
+# usually tell ou more than the mones from reverse 
+# lookups. 
+#
+# This has been tested on debian and asuswrt. Plese
+# report successful tests on other platforms.
+#
+# Author: Joachim Zobel <jz-2014@heute-morgen.de>
+# License: Consider this MIT style licensed. You can 
+#   do as you ike, but you must not remove my name.
 #
 
-DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+LOG=/var/log/dnsmasq.log
-DNS=$DIR/reverse_dns.sh
+MAX_LINES=15000
 
-# sed regex
+# sed regex do match IPs
 IP_regex='[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}'
+# private IP ranges
+IP_private='\(^127\.\)\|\(^192\.168\.\)\|\(^10\.\)\|\(^172\.1[6-9]\.\)\|\(^172\.2[0-9]\.\)\|\(^172\.3[0-1]\.\)'
+
+#######################################################################
+# Find Commands
+  
+HOST=nslookup
+if type host > /dev/null 2>&1; then
+  # echo "No need for nslookup, host is there"
+  HOST=host
+fi
+
+#######################################################################
+# Functions
+
+# Use shell variables for an (IP) lookup table
+create_lookup_table()
+{
+  # Parse log into lookup table
+  local CMDS="$( tail -"$MAX_LINES" "$LOG" | \
+    grep " is $IP_regex" | \
+    sed "s#.* \([^ ]*\) is \($IP_regex\).*#set_val \2 \1;#" )"
+
+  local IFS='
+'
+  for CMD in $CMDS
+  do
+    eval $CMD
+  done
+}
+
+set_val()
+{
+  local _IP=$(echo $1 | tr . _)
+  local KEY="__IP__$_IP"
+  eval "$KEY"=$2
+}
+
+get_val()
+{
+  local _IP=$(echo $1 | tr . _)
+  local KEY="__IP__$_IP"
+  eval echo -n '${'"$KEY"'}'
+}
+
+dns_lookup()
+{
+  local IP=$1
+
+  local RTN="$($HOST $IP | \
+        sed 's#\s\+#\n#g' | \
+        grep -v '^$' | \
+        tail -1 | tr -d '\n' | \
+        sed 's#\.$##')"
+  if echo $RTN | grep -q NXDOMAIN; then
+    echo -n $IP
+  else
+    echo -n "$RTN"
+  fi     
+}
+
+reverse_dns()
+{
+  local IP=$1
+
+  # Skip if it is not an IP
+  if ! echo $IP | grep -q "^$IP_regex$"; then
+    echo -n $IP
+    return 
+  fi
+    
+  # Do a dns lookup, if it is a local IP
+  if echo $IP | grep -q $IP_private; then
+    dns_lookup $IP
+    return
+  fi
+    
+  local NAME="$(get_val $IP)"
+  
+  if [ -z "$NAME" ]; then
+    echo -n $IP
+  else
+    echo -n $NAME
+  fi
+}
+
+#######################################################################
+# Main
+create_lookup_table
 
 while read LINE; do
-  if grep --quiet $IP_regex <<< "$LINE"; then
+  for IP in $(echo "$LINE" | \
-    IPs=`sed "s#.*\b\($IP_regex\)\b.*#\1 #g" <<< "$LINE"`
+              sed "s#\b\($IP_regex\)\b#\n\1\n#g" | \
-    IPs=($IPs)
+              grep $IP_regex) 
-    for IP in "${IPs[@]}"
   do
-      NAME=`$DNS $IP`
+    NAME=`reverse_dns $IP `
-      # echo "$NAME is $IP";
+    # echo "$NAME $IP"
-      LINE="${LINE/$IP/$NAME}" 
+    LINE=`echo "$LINE" | sed "s#$IP#$NAME#" ` 
   done
-  fi
   echo $LINE
-done < /dev/stdin
+done