Doing iperf between my eth0 and eth1 of same board

Hi,
i want to do iperf test from eth0 and eth1 of my board.i searched in internet and i found that for that i need to install iptable.after i installed iptable(i got a cross compiled binary from net and just untar it and place the files in the /usr).but after that ,when i give "iptables -t nat -L",it is showing message as "iptables v1.4.21: can't initialize iptables table `nat': Table does not exist (do you need to insmod?)".in make menuconfig i enabled all the options related to iptable and netfiltering ,but it still shows same error.please help.thanks for your time.

Hi Andrew,

It would be a big help if you could tell us what distro you're running.

Output of uname -r is "3.9.0-xilinx".i sucessfully compiled kernel modules for ip forwarding,now that problem solved.now i want to ping or do iperf between eth0 and eth1 ,which are class c networks in different domain.