transparent_proxy.sh

#!/bin/bash
set -o errexit

# Aliases
IPT=/sbin/iptables

printf 'Cleaning the environment... '

# Delete the PROXY chain
($IPT --table nat --delete-chain PROXY || true)  2> /dev/null # ignore error
echo "Done"

# Create new chain
$IPT --table nat -N PROXY

# Any tcp connection made by group `socksified' or user root should be redirected.
$IPT --table nat --append OUTPUT --protocol tcp --match owner ! --uid-owner redsocks --jump PROXY

# Ignore LANs and some other reserved addresses.
# See http://en.wikipedia.org/wiki/Reserved_IP_addresses#Reserved_IPv4_addresses
# and http://tools.ietf.org/html/rfc5735 for full list of reserved networks.
noproxy=(
	'0.0.0.0/8'
	'10.0.0.0/8'
	'127.0.0.0/8'
	'169.254.0.0/16'
	'172.16.0.0/12'	
	'192.168.0.0/16'
	'224.0.0.0/4'
	'240.0.0.0/4' 
	# add any other local address here
)

for ip in "${noproxy[@]}"; do
	echo "Skipping proxy for ${ip}"
	$IPT --table nat --append PROXY -d ${ip} --jump RETURN
done

# Log everything that goes through the PROXY chain to syslog
$IPT --table nat --append PROXY --protocol tcp --jump LOG --log-level debug --log-prefix "[PROXY]"

# Anything else should be redirected to port 8080
$IPT --table nat --append PROXY --protocol tcp --jump REDIRECT --to-ports 8080

# printf "\n\nHere are your new iptables rules:\n"
# $IPT --table nat -nvL PROXY --line-numbers

echo "Dont forget to configure redsocks"