From fec8686c4edca8b78b273354626d4c88bb777746 Mon Sep 17 00:00:00 2001
From: Sven Hartge <sven@svenhartge.de>
Date: Fri, 20 Apr 2012 00:49:14 +0200
Subject: [PATCH 1/2] arp: simple plugins to monitor a hosts ARP cache

---
 plugins/arp/arp  | 43 +++++++++++++++++++++++++++++++++++++
 plugins/arp/arp_ | 56 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)
 create mode 100755 plugins/arp/arp
 create mode 100755 plugins/arp/arp_

diff --git a/plugins/arp/arp b/plugins/arp/arp
new file mode 100755
index 00000000..a6657551
--- /dev/null
+++ b/plugins/arp/arp
@@ -0,0 +1,43 @@
+#!/bin/sh
+#
+# Plugin to monitor total ARP entries
+#
+#  Parameters understood:
+#
+#      config   (required)
+#      autoconf (optional)
+#
+#  Made by Sven Hartge (sven AT svenhartge DOT de)
+#
+
+#%# family=contrib
+#%# capabilities=autoconf
+
+if [ "$1" = "autoconf" ]; then
+    # Search for arp
+    which arp >/dev/null 2>/dev/null || (echo "no (can't find arp binary)" && exit 1)
+
+    # ...or success
+    echo yes
+    exit 0
+fi
+
+
+
+if [ "$1" = "config" ]; then
+        echo 'graph_title ARP entries'
+        echo 'graph_args --base 1000 -l 0'
+        echo 'graph_vlabel Entries'
+        echo 'graph_category network'
+	echo 'graph_scale no'
+        echo 'graph_info This graph shows the number of ARP entries registered by the system.'
+	echo 'entries.label ARP entries'
+	echo 'entries.draw LINE2'
+	echo 'entries.type GAUGE'
+	echo 'entries.info Number of ARP entries'
+	exit 0
+fi
+
+echo -n "entries.value "
+arp -an | grep -v "incomplete" | awk '{ print $4; }' | sort -u | wc -l 
+
diff --git a/plugins/arp/arp_ b/plugins/arp/arp_
new file mode 100755
index 00000000..24667f02
--- /dev/null
+++ b/plugins/arp/arp_
@@ -0,0 +1,56 @@
+#!/bin/sh
+#
+# Plugin to monitor ARP entries per interface
+#
+# Parameters understood:
+#
+#       config   (required)
+#       autoconf (optional)
+#
+#  Made by Sven Hartge (sven AT svenhartge DOT de)
+#
+#
+
+
+#%# family=contrib
+#%# capabilities=autoconf suggest
+
+INTERFACE=`basename $0 | sed 's/^arp_//g' | tr '_' '.'`
+
+if [ "$1" = "autoconf" ]; then
+    # Search for arp
+    which arp >/dev/null 2>/dev/null || (echo "no (can't find arp binary)" && exit 1)
+
+    # ...or success
+    echo yes
+    exit 0
+fi
+
+if [ "$1" = "suggest" ]; then
+  if [ -r /proc/net/dev ]; then
+    egrep '^ *(eth|wlan|ath|ra)[0-9]+(\.[0-9]+)?:' /proc/net/dev | cut -f1 -d: | sed 's/ //g' | tr '.' '_'
+    exit 0
+  else
+    exit 1
+  fi
+fi
+
+
+
+if [ "$1" = "config" ]; then
+        echo "graph_title ARP entries for $INTERFACE"
+        echo 'graph_args --base 1000 -l 0'
+        echo 'graph_vlabel Entries'
+        echo 'graph_category network'
+	echo 'graph_scale no'
+        echo "graph_info This graph shows the number of ARP entries registered by the system for interface $INTERFACE."
+	echo 'entries.label ARP entries'
+	echo 'entries.draw LINE2'
+	echo 'entries.type GAUGE'
+	echo 'entries.info Number of ARP entries'
+	exit 0
+fi
+
+echo -n "entries.value "
+arp -an -i $INTERFACE | grep -v "incomplete" | awk '{ print $4; }' | sort -u | wc -l 
+

From 4a56eb18976700f6fc460a1b910544421a484cf2 Mon Sep 17 00:00:00 2001
From: Sven Hartge <sven@svenhartge.de>
Date: Fri, 20 Apr 2012 15:19:22 +0200
Subject: [PATCH 2/2] arp: use only awk to process ARP cache

Simplify the processing of the output of arp -an to use only awk.
Reduces the needed subprocesses in the pipe.
---
 plugins/arp/arp  | 3 +--
 plugins/arp/arp_ | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/plugins/arp/arp b/plugins/arp/arp
index a6657551..8addffa3 100755
--- a/plugins/arp/arp
+++ b/plugins/arp/arp
@@ -38,6 +38,5 @@ if [ "$1" = "config" ]; then
 	exit 0
 fi
 
-echo -n "entries.value "
-arp -an | grep -v "incomplete" | awk '{ print $4; }' | sort -u | wc -l 
+arp -an | awk 'BEGIN { regex="<incomplete>";} { if (!match($4,regex)) { a[$4] }} END{for(i in a){n++};print "entries.value " n}'
 
diff --git a/plugins/arp/arp_ b/plugins/arp/arp_
index 24667f02..adbd86c3 100755
--- a/plugins/arp/arp_
+++ b/plugins/arp/arp_
@@ -51,6 +51,5 @@ if [ "$1" = "config" ]; then
 	exit 0
 fi
 
-echo -n "entries.value "
-arp -an -i $INTERFACE | grep -v "incomplete" | awk '{ print $4; }' | sort -u | wc -l 
+arp -an -i $INTERFACE | awk 'BEGIN { regex="<incomplete>";} { if (!match($4,regex)) { a[$4] }} END{for(i in a){n++};print "entries.value " n}'