#!/bin/sh
#
# Wildcard-plugin to monitor forward traffic for network interfaces through iptables. To monitor an
# interface, link if_forward_<interface> to this file. E.g.
#
#    ln -s /usr/share/node/node/plugins-auto/if_forward_ /etc/munin/node.d/if_forward_eth0
#
# ...will monitor forwarded traffic through eth0.
#
# Additionally, you need these iptables rules as the first rules (they don't do anything, just make packet counts)
#
#    iptables -A FORWARD -i eth0
#    iptables -A FORWARD -o eth0
#
# Furthermore, this plugin needs to be run as root for iptables to work
#
# This plugin is based on the if_ and ip_ plugin.
#
# Magic markers (optional - used by munin-config and some installation
# scripts):
#
#%# family=auto
#%# capabilities=autoconf suggest


IF=`basename $0 | sed 's/^if_forward_//g'`

if [ "$1" = "autoconf" ]; then
	if [ -r /proc/net/dev ]; then
		iptables-save -c >/dev/null 2>/dev/null
		if [ $? -gt 0 ]; then
			echo "no (could not run iptables-save as user `whoami`)"
		else
			echo yes
		fi
	else
		echo "no (/proc/net/dev not found)"
	fi
	exit 0
fi

if [ "$1" = "suggest" ]; then
	if [ -r /proc/net/dev ]; then
		egrep '^ *(eth|wlan|ath|ra)[0-9]+:' /proc/net/dev | cut -f1 -d: | sed 's/ //g'
		exit 0
	else
		exit 1
	fi
fi

if [ "$1" = "config" ]; then

        echo "graph_order out in"
        echo "graph_title $IF forwarded traffic"
        echo 'graph_args --base 1000'
        echo 'graph_vlabel bits per ${graph_period}'
	echo 'graph_category network'
	echo "graph_info This graph shows only FORWARD traffic that pass through the interface."
        echo 'out.label sent'
        echo 'out.type DERIVE'
        echo 'out.min 0'
        echo 'out.cdef out,8,*'
        echo 'in.label received'
        echo 'in.type DERIVE'
        echo 'in.min 0'
        echo 'in.cdef in,8,*'
        exit 0
fi;

iptables-save -c | grep $IF | grep i | cut -f2 -d':' | cut -f1 -d']' | awk "{ print \"in.value \" \$0 }"
iptables-save -c | grep $IF | grep o | cut -f2 -d':' | cut -f1 -d']' | awk "{ print \"out.value \" \$0 }"