hi all I am using uClinux to test nat on IXDP425 the setup is use is as shown below LAN with subnet <-------------[ixp0:10.0.10.11/23 (IXDP425) ixp1: 192.168.0.1/24]----------->PC with 10.0.10.0/23 IP 192.168.0.4/24 Default Gateway 192.168.0.1 now here th IXDP425 acting as router with ip_forward = 1 ixp0(eth1) with IP 10.0.10.11 is acting as WAN port connecting to LAN of subnet 10.0.10.0/23 and ixp1(eth0) is acting as LAN port connecting to PC of IP 192.168.0.4 with default gateway as 192.168.0.1 I have inserted all modules required for filter and nat applications viz. insmod ip_tables.o insmod ip_conntrack.o insmod iptable_filter.o insmod iptable_nat.o insmod ipt_LOG.o insmod ipt_limit.o insmod ipt_state.o insmod ipt_MASQUERADE.o insmod ip_conntrack_ftp.o insmod ip_conntrack_irc.o insmod ip_nat_ftp.o insmod ip_nat_irc.o insmod iptable_mangle.o now the scrip i have done for nat is LOOPBACK=lo LAN=ixp1 WAN=ixp0 #Flush any rules that may still be configured iptables -t filter -F INPUT iptables -t filter -F OUTPUT iptables -t filter -F FORWARD iptables -t nat -F PREROUTING iptables -t nat -F POSTROUTING iptables -t nat -F OUTPUT # Set the default policies for the chains iptables -t filter -P INPUT DROP iptables -t filter -P OUTPUT ACCEPT iptables -t filter -P FORWARD DROP iptables -t nat -P PREROUTING ACCEPT iptables -t nat -P POSTROUTING ACCEPT iptables -t nat -P OUTPUT ACCEPT # Set up the firewall rules iptables -t filter -A INPUT -i ${LOOPBACK} -j ACCEPT iptables -t filter -A INPUT -i ${LAN} -j ACCEPT iptables -t filter -A INPUT -i ${WAN} -j ACCEPT # Set up the ip forwarding echo "1" > /proc/sys/net/ipv4/ip_forward iptables -t filter -A FORWARD -i ${LAN} -o ${WAN} -j ACCEPT iptables -t filter -A FORWARD -i ${WAN} -o ${LAN} -j ACCEPT iptables -t nat -A POSTROUTING -s 192.168.0.4 -o ${LAN} -j SNAT --to 10.0.10.11 now i am pinging 10.0.10.x/23 machine from 192.168.0.4 machine but it is not doing it WHY? I have captured the packets using ethereal at 10.0.10.x/23 (the machine to which i am pinging) and the result is The IP of 192.168.0.4 is the same in packet but according to me it should change to 10.0.10.11 can anyone help me to solve this problem? thanks rahul