On Linux server, after upgrading kernel, i got following error.
[[email protected] 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.
[[email protected] lib]#
The error is due to kernel combiled with out iptables support. Recompiling kernel with netfilter support solved the problem.