Hi I am getting the error as mentioned below; the problem arose when I have changed the data structure of the ipt_entry which stores the rules and other information. I have changed in the also other appropriate initialization of the structure in ip_nat_rule and other files. I have just added one variable of type unsigned int. Can any one have idea regarding this problem. Before adding this variable, iptables was working fine. Can any one help me in this problem. [root@localhost ~]# service iptables start Flushing firewall rules: iptables: Unknown error 4294967295 iptables: Unknown error 4294967295 iptables: Unknown error 4294967295 iptables: Unknown error 4294967295 iptables: Unknown error 4294967295 iptables: Unknown error 4294967295 iptables: Unknown error 4294967295 [FAILED] Setting chains to policy ACCEPT: raw iptables: Unknown error 4294967295 nat iptables: Unknown error 4294967295 mangle iptables: Unknown error 4294967295 filter iptables: Unknown error 4294967295 [FAILED] Unloading iptables modules: [ OK ] All the modules have been loaded as permanent modules rather than as loadable modules.