Hi, I am reading ip_tables.h. There is a structure called ipt_target. In it there is pointer to a function which is below. unsigned int (*target )(struct sk_buff **pskb, .......) I can not find the original function that this function pointer(*target) points. When I search for target, I see that it is defined in 6 files. Which one is used and when? How can I understand it? (this is same for match and checkentry functions) 6 files in which target is defined; * net/ipv4/netfilter/ipt_ECN.c, line 104 * net/ipv4/netfilter/ipt_DSCP.c, line 25 * net/ipv4/netfilter/ipt_MARK.c, line 11 * net/ipv4/netfilter/ipt_TOS.c, line 11 * net/ipv6/netfilter/ip6t_MARK.c, line 11 thanks, -- Ozgur Akan