>I know how to intercept tcp packets at NF_IP_PRE_ROUTING and do what I have to, but how to put the packet back to >either NF_IP_LOCAL_IN or NF_IP_LOCAL_OUT in network stack path. >If you can point me example code that will be great. Dear Chen, First of all, you can go through the following link. http://www.netfilter.org/documentation/HOWTO//netfilter-hacking-HOWTO.ht ml Please find some sample code below. I think it may help you. Thanks and Regards, Srinivas G ======================================================================== === /* define netfilter structure here */ static struct nf_hook_ops netfilter_hook; /* pointer to a buffer */ unsigned char *ptr_packet_buff; /* function prototype which is called when a packet arrives */ unsigned int netfilter_drv_hook(unsigned int hooknum, struct sk_buff **skb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { printk("One Packet arrvied!\n"); /* alocate the packet buffer */ ptr_packet_buff = (unsigned char *)vmalloc(MAX_PACK_BUFF); /* the received packet was dropped here itself */ return NF_QUEUE; } /* netfilter_init: initialization function */ static int __init init_netfilter(void) { printk("invoked!\n"); /* assign the function pointer */ netfilter_hook.hook = netfilter_drv_hook; /* assign the protocol family i.e. IPv4 */ netfilter_hook.pf = PF_INET; /* assign the hook number like NF_IP_LOCAL_IN etc. */ netfilter_hook.hooknum = NF_IP_PRE_ROUTING; /* assign the hook priority */ netfilter_hook.priority = NF_IP_PRI_FIRST; /* register the netfilter driver with pointer to structure */ nf_register_hook(&netfilter_hook); return 0; } /* netfilter_exit: cleanup function */ static void __exit netfilter_exit(void) { printk("invoked!\n"); /* unregister the driver */ nf_unregister_hook(&netfilter_hook); } /* explicit module definitions */ module_init(init_netfilter); module_exit(netfilter_exit); ======================================================================== == -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
