iptables Error

On Linux server, after upgrading kernel, i got following error.

[root@linux lib]# iptables -L
iptables v1.2.11: can't initialize iptables table `filter': iptables who? (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
[root@linux lib]#

The error is due to kernel combiled with out iptables support. Recompiling kernel with netfilter support solved the problem.