taglinefilesource code
fw_res96net/ipv4/ip_forward.cint fw_res = 0;    /* Forwarding result */  
fw_res109net/ipv4/ip_forward.cfw_res=call_fw_firewall(PF_INET, skb, skb->h.iph);
fw_res110net/ipv4/ip_forward.cswitch (fw_res) {
fw_res240net/ipv4/ip_forward.cif (!(is_frag&4) && fw_res==FW_MASQUERADE)