Forwarding through iptables, with 3 NICs

Hello all,

I am attempting to route traffic from eth0 port 443 to our IIS server
(this is working), while routing eth2 port 443 traffic to the CSG
server. I see traffic coming into eth2, but according to tcpdump,
nothing is exiting to eth1. There is only a single Internet
connection in my setup, with two external IP addys. BTW, I have some
other Citrix-based routing going on as well to other boxes. Summary
listing is below, and iptables script included.

What am I missing here...it must be something simple? Thanks in
advance.

Cheers,
Jim

________________
/--|static IP (eth0)| -- IIS Server
/----/ | | /
Internet------Switch--------|LAN IP (eth1)---------DMZ
\----\ | | \
\--|static IP (eth2)| -- CSG Server
|________________|
LINUX BOX


<begin summary>

iptables -t nat -L -vn
Chain PREROUTING (policy ACCEPT 550 packets, 79691 bytes)
pkts bytes target prot opt in out source
destination
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
2 96 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
2 96 DNAT tcp -- eth2 * 0.0.0.0/0
64.xxx.xxx.xxx tcp dpt:443 to:157.208.75.64
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
0 0 DNAT tcp -- eth2 * 0.0.0.0/0
64.xxx.xxx.xxx tcp dpt:443 to:157.208.75.64
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
0 0 DNAT tcp -- eth2 * 0.0.0.0/0
64.xxx.xxx.xxx tcp dpt:443 to:157.208.75.64
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
0 0 DNAT tcp -- eth2 * 0.0.0.0/0
64.xxx.xxx.xxx tcp dpt:443 to:157.208.75.64
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
0 0 DNAT tcp -- eth2 * 0.0.0.0/0
64.xxx.xxx.xxx tcp dpt:443 to:157.208.75.64
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
0 0 DNAT tcp -- eth2 * 0.0.0.0/0
64.xxx.xxx.xxx tcp dpt:443 to:157.208.75.64
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:1494 to:157.208.75.49
0 0 DNAT tcp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx tcp dpt:443 to:157.208.75.128
0 0 DNAT udp -- eth0 * 0.0.0.0/0
207.xxx.xxx.xxx udp dpt:1604 to:157.208.75.49
0 0 DNAT tcp -- eth2 * 0.0.0.0/0
64.xxx.xxx.xxx tcp dpt:443 to:157.208.75.64

Chain POSTROUTING (policy ACCEPT 53 packets, 4380 bytes)
pkts bytes target prot opt in out source
destination
37 2626 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:64.xxx.xxx.xxx
0 0 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:64.xxx.xxx.xxx
0 0 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:64.xxx.xxx.xxx
0 0 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:64.xxx.xxx.xxx
0 0 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:64.xxx.xxx.xxx
0 0 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth0 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx
0 0 SNAT all -- * eth2 0.0.0.0/0
0.0.0.0/0 to:207.xxx.xxx.xxx

Chain OUTPUT (policy ACCEPT 76 packets, 6171 bytes)
pkts bytes target prot opt in out source
destination





<begin firewall script>

#!/bin/sh
#
################################################## #########################
#
# 1. Configuration options.
#

################################################## #########################
#
# Local Area Network configuration.
#
# LAN's IP range and localhost IP. /24 means to only use the first 24
# bits of the 32 bit IP adress. the same as netmask 255.255.255.0
#

LAN_IP="157.208.75.48"
LAN_IP_RANGE="157.208.75.0/24"
LAN_BCAST_ADRESS="157.208.75.48"
LAN_IFACE="eth1"


################################################## #########################
#
# Localhost Configuration.
#

LO_IFACE="lo"
LO_IP="127.0.0.1"

################################################## #########################
#
# Internet Configuration.
#

INET_IP="207.xxx.xxx.xxx"
INET_IFACE="eth0"

INET_IP2="64.xxx.xxx.xxx"
INET_IFACE2="eth2"


################################################## #########################
#
# IPTables Configuration.
#

IPTABLES="/sbin/iptables"

################################################## #########################
#
# Port Forwarding Configuration.
#

CITRIX_SERVER="157.208.75.49"
IIS_SERVER="157.208.75.128"
CSG_SERVER="157.208.75.64"



################################################## #########################
#
# 2. Module loading.
#

echo "Loading kernel modules..."

#
# Needed to initially load modules
#
/sbin/depmod -a

#
# Adds some iptables targets like LOG, REJECT and MASQUARADE.
#
/sbin/modprobe ip_conntrack
/sbin/modprobe ip_tables
/sbin/modprobe iptable_filter
/sbin/modprobe iptable_mangle
/sbin/modprobe iptable_nat
/sbin/modprobe ipt_LOG
#/sbin/modprobe ipt_REJECT
#/sbin/modprobe ipt_MASQUERADE

#
# Support for owner matching
#
#/sbin/modprobe ipt_owner

#
# Support for connection tracking of FTP and IRC.
#
#/sbin/modprobe ip_conntrack_ftp
#/sbin/modprobe ip_conntrack_irc


################################################## #########################
#
# 3. /proc set up.
#
# Enable ip_forward if you have two or more networks, including the
# Internet, that needs forwarding of packets through this box. This is
# critical since it is turned off as default in Linux.
#

echo "Enabling IP forwarding..."

echo "1" > /proc/sys/net/ipv4/ip_forward

#
# Dynamic IP users:
#
#echo "1" > /proc/sys/net/ipv4/ip_dynaddr

################################################## #########################
#
# 4. IPTables rules set up.
#
# Clean old rules
#
echo "Flushing old rules"

$IPTABLES -F
$IPTABLES -X
$IPTABLES -Z


# Set default policies for the INPUT, FORWARD and OUTPUT chains.
# (Block all requests)

echo "Setting default policies..."


$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP

#
# bad_tcp_packets chain
#
# Take care of bad TCP packets that we don't want.
#

$IPTABLES -N bad_tcp_packets
$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

#
# Do some checks for obviously spoofed IP's
#

$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 192.168.0.0/16 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 10.0.0.0/8 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 172.16.0.0/12 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE2 -s 192.168.0.0/16 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE2 -s 10.0.0.0/8 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE2 -s 172.16.0.0/12 -j DROP

#
# Enable simple IP Forwarding and Network Address Translation
#

$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT --to-source
$INET_IP
$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE2 -j SNAT --to-source
$INET_IP


#
# Bad TCP packets we don't want
#

$IPTABLES -A FORWARD -p tcp -j bad_tcp_packets


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

$IPTABLES -N icmp_packets
$IPTABLES -N tcp_packets
$IPTABLES -N udpincoming_packets

#
# The allowed chain for TCP connections
#

$IPTABLES -N allowed
$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

echo "Setting ICMP and TCP rules..."

#
# ICMP rules
#

# Changed rules totally
$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

#
# TCP rules
#

$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 25 -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 443 -j allowed

#
# UDP ports
#

# nondocumented commenting out of these rules
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 2074 -j
ACCEPT
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 4000 -j
ACCEPT


##########################
# INPUT chain
#
# Bad TCP packets we don't want.
#

$IPTABLES -A INPUT -p tcp -j bad_tcp_packets

#
# Rules for incoming packets from the internet.
#

$IPTABLES -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets
$IPTABLES -A INPUT -p TCP -i $INET_IFACE -j tcp_packets
$IPTABLES -A INPUT -p UDP -i $INET_IFACE -j udpincoming_packets
$IPTABLES -A INPUT -p ICMP -i $INET_IFACE2 -j icmp_packets
$IPTABLES -A INPUT -p TCP -i $INET_IFACE2 -j tcp_packets
$IPTABLES -A INPUT -p UDP -i $INET_IFACE2 -j udpincoming_packets

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

$IPTABLES -A INPUT -p ALL -i $LAN_IFACE -d $LAN_BCAST_ADRESS -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
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $INET_IP2 -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LAN_IFACE -s $LAN_IP_RANGE -j ACCEPT
$IPTABLES -A INPUT -p ALL -d $INET_IP -m state --state
ESTABLISHED,RELATED \
-j ACCEPT
$IPTABLES -A INPUT -p ALL -d $INET_IP2 -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: "

###############################
# OUTPUT chain
#
#
# Bad TCP packets we don't want.
#

$IPTABLES -A OUTPUT -p tcp -j bad_tcp_packets

#
# Special OUTPUT rules to decide which IP's to 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
$IPTABLES -A OUTPUT -p ALL -s $INET_IP2 -j ACCEPT

#
# Log weird packets that don't match the above.
#

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

#
# Accept the packets we actually want to forward
#

echo "Setting new forward rules..."


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

#Permit forward in firewall
$IPTABLES -A FORWARD -i eth0 -o eth1 -p tcp -d $CITRIX_SERVER --dport
1494 -j ACCEPT
$IPTABLES -A FORWARD -i eth0 -o eth1 -p tcp -d $IIS_SERVER --dport 443
-j ACCEPT
$IPTABLES -A FORWARD -i eth0 -o eth1 -p udp -d $CITRIX_SERVER --dport
1604 -j ACCEPT
$IPTABLES -A FORWARD -i eth2 -o eth1 -p tcp -d $CSG_SERVER --dport 443
-j ACCEPT



#$IPTABLES -A FORWARD -i eth0 -o eth2 -j ACCEPT
#$IPTABLES -A FORWARD -i eth2 -o eth0 -j ACCEPT



#DNAT
$IPTABLES -t nat -A PREROUTING -i eth0 -p tcp -d $INET_IP --dport 1494
-j DNAT --to $CITRIX_SERVER
$IPTABLES -t nat -A PREROUTING -i eth0 -p tcp -d $INET_IP --dport 443
-j DNAT --to $IIS_SERVER
$IPTABLES -t nat -A PREROUTING -i eth0 -p udp -d $INET_IP --dport 1604
-j DNAT --to $CITRIX_SERVER
$IPTABLES -t nat -A PREROUTING -i eth2 -p tcp -d $INET_IP2 --dport 443
-j DNAT --to $CSG_SERVER

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

echo "FIREWALL loaded!"