iptables/Port Forwarding issues

[linux supernoob]

Heres the situation...

Im using a linux box as a router for my network with limited success. I have one static ip address and i need to forward all http requests to my web server on my internal network at 192.168.0.10

Ive read all the tutorials and i thought my firewall was set up properly but i still can not connect to my web server from outside my network.

Im posting my script. If anyone can spot the problem id appreciate it.

[linux supernoob]

Heres the script in case some people dont want to dl it.


#!/bin/bash
#
# rc.firewall -
#
################################################## ###############################
# 1. Configuration Options
#

#
# 1.1 Internet Configuration.
#

INET_IP="xx.xx.xx.xxx"
INET_IFACE="eth0"
INET_BROADCAST="xx.xx.xx.xxx"

#
# 1.1.1 DHCP
#

#
# 1.1.2 PPPoE
#

#
# 1.2 Local Area Network
#

LAN_IP="192.168.0.1"
LAN_IP_RANGE="192.168.0.0/24"
LAN_IFACE="eth1"
DNS_IP="192.168.0.10"
HTTP_IP="192.168.0.10"
FTP_IP="192.168.0.10"

#
# 1.3 DMZ Configuration
#

#
# 1.4 Localhost Configuration
#

LO_IFACE="lo"
LO_IP="127.0.0.1"

#
# 1.5 iptables configuration
#

IPTABLES="/sbin/iptables"

################################################## ###############################
# 2.Load extra modules
#

/sbin/depmod -a

#
# 2.1 Required modules
#

/sbin/modprobe ip_tables
/sbin/modprobe ip_conntrack
/sbin/modprobe iptable_filter
/sbin/modprobe iptable_mangle
/sbin/modprobe iptable_nat
/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_limit
/sbin/modprobe ipt_state

#
# 2.2 Non-Required modules
#

/sbin/modprobe ipt_owner
/sbin/modprobe ipt_REJECT
/sbin/modprobe ipt_MASQUERADE
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe ip_conntrack_irc
#/sbin/modprobe ipt_nat_ftp
/sbin/modprobe ip_nat_irc
################################################## #############################o#
# 3. /proc setup
#

#
# 3.1 Required proc information
#

echo "1" > /proc/sys/net/ipv4/ip_forward
#
# 3.2 routing setup
#

################################################## ###############################
# 4. rules setup
#

######
# Filter table
#
$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP

#
# 4.1.2 Create user specified chains
#

#
# Create chain for bad tcp packets
#

$IPTABLES -N bad_tcp_packets

#
# Create seperate chains for ICMP, TCP, and UDP to traverse
#

$IPTABLES -N allowed
$IPTABLES -N tcp_packets
$IPTABLES -N udp_packets
$IPTABLES -N icmp_packets

#
# 4.1.3 Create content in user specified chains
#

#
# bad_tcp_packets chain
#

$IPTABLES -A bad_tcp_packets -p tcp --tcp-flags SYN,ACK SYN,ACK \-m state --state NEW -j REJECT --reject-with tcp-reset
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG \--log-prefix "New not syn:"
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP

#
# allowed chain
#

$IPTABLES -A allowed -p TCP --syn -j ACCEPT
$IPTABLES -A allowed -p TCP -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A allowed -p TCP -j DROP

#
# TCP rules
#
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 20 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 21 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 22 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 23 -j allowed
#$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 53 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 80 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 113 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 5273 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 7002 -j allowed

# UDP ports
#

$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 20 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 21 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 53 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 27015 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 27010 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 27012 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 4000 -j ACCEPT
#
# ICMP rules
#

$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT

#
# 4.1.4 INPUT chain
#

#
# Bad TCP packets we dont want
#

$IPTABLES -A INPUT -p tcp -j bad_tcp_packets

#
# Rules for special networks not part of the internet
#

$IPTABLES -A INPUT -p ALL -i $LAN_IFACE -s $LAN_IP_RANGE -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LO_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LAN_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $INET_IP -j ACCEPT
#
# special rules for DHCP
#
#
# Rules for incoming packets from the internet
#

$IPTABLES -A INPUT -p ALL -d $INET_IP -m state --state ESTABLISHED,RELATED \-j ACCEPT
$IPTABLES -A INPUT -p TCP -i $INET_IFACE -j tcp_packets
$IPTABLES -A INPUT -p UDP -i $INET_IFACE -j udp_packets
$IPTABLES -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets

#
# Log weird packets that dont match above
#

$IPTABLES -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \--log-level DEBUG --log-prefix "IPT INPUT packet died: "

#
# 4.1.5 FORWARD chain
#

#
# Bad TCP packets we dont want
#

$IPTABLES -A FORWARD -p tcp -j bad_tcp_packets

#
# Accept the packets we actually want to forward
#

$IPTABLES -A FORWARD -i $LAN_IFACE -j ACCEPT
$IPTABLES -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

#
# Log weird packets that dont match the above
#

$IPTABLES -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG \--log-level DEBUG --log-prefix "IPT FORWARD packet died: "

#
# 4.1.6 OUTPUT chain
#

#
# Bad TCP packets we dont want
#

$IPTABLES -A OUTPUT -p tcp -j bad_tcp_packets

#
# Special OUTPUT rules to decide which IP's allow
#

$IPTABLES -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $INET_IP -j ACCEPT

#
# Log weird packets that dont match above
#

$IPTABLES -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \--log-level DEBUG --log-prefix "IPT OUTPUT packed died: "

######
# 4.2 nat tables
#


#
# 4.2.1 Set policies
#

#
# 4.2.2 Create user specified chains
#

#
# 4.2.3 Create content in user specified chains
#

#
# 4.2.4 PREROUTING chain
#
$IPTABLES -t nat -A PREROUTING --dst $INET_IP -p tcp --dport 80 -j DNAT \--to-destination $HTTP_IP

#
# 4.2.5 POSTROUTING chain
#

$IPTABLES -t nat -A POSTROUTING -p tcp --dst $HTTP_IP --dport 80 -j SNAT \--to-source $LAN_IP
#
# Enable simple IP Forwarding and Network Address Translation
#
$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT --to-source $INET_IP

#
# 4.2.6 OUTPUT chain
#

[je_fro]

When you copied this file, you included the forward slashes that were placed so the newline characters would be ignored. It looks good, just pull the forward slashes out.

$IPTABLES -A INPUT -p ALL -d $INET_IP -m state --state ESTABLISHED,RELATED \-j ACCEPT

$IPTABLES -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \--log-level DEBUG --log-prefix "IPT INPUT packet died: "

$IPTABLES -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG \--log-level DEBUG --log-prefix "IPT FORWARD packet died: "

$IPTABLES -t nat -A PREROUTING --dst $INET_IP -p tcp --dport 80 -j DNAT \--to-destination $HTTP_IP




Example, the last line should be:

$IPTABLES -t nat -A PREROUTING --dst $INET_IP -p tcp --dport 80 -j DNAT --to-destination $HTTP_IP

[linux supernoob]

thanks je_fro

ill give it a try right now.

what is the signifigance of those slashes. I just ask because thats the way the example showed to put them in the tutorial i read.

[linux supernoob]

oh i see..
they represent a newline.
sorry im not thinkin straight right now.

[je_fro]

As the author was typing along, he wanted to \
keep everything on one skinny page , so he \
would put an escape character before he hit \
RETURN and people could then just copy and \
paste the script and it would work fine unless \
someone edited out the RETURN characters.


That's a pretty good script, though. I got pieces of my 'wall from it, but I lost the link. Can you post the link it came from?

[linux supernoob]

Yeah..

its part of a tutorial that i found helpful...
Its at the very end of the page.

http://iptables-tutorial.frozentux.net/iptables-tutorial.html