On Tue, 2012-05-08 at 09:49 +0530, rohan puri wrote:
>
>
> On Tue, May 8, 2012 at 9:37 AM, Chir0n <io.chir0n@xxxxxxxxx> wrote:
> I'm using this Makefile:
>
> obj-m += hello.o
>
> all:
> make -C /lib/modules/$(shell uname -r)/build M=$(PWD)
> modules
>
> clean:
> make -C /lib/modules/$(shell uname -r)/build M=$(PWD)
> clean
>
>
> The hello.c is this:
>
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/netfilter.h>
> #include <linux/netfilter_ipv4.h>
>
> static struct nf_hook_ops nfho; //struct holding set
> of hook function options
>
> //function to be called by hook
> unsigned int hook_func(unsigned int hooknum, struct sk_buff
> **skb, const struct net_device *in, const struct net_device
> *out, int (*okfn)(struct sk_buff *))
> {
> printk(KERN_INFO "packet dropped\n");
> //log to var/log/messages
> return NF_DROP;
> //drops the packet
> }
>
> //Called when module loaded using 'insmod'
> int init_module()
> {
> nfho.hook = hook_func; //function to
> call when conditions below met
> nfho.hooknum = NF_IP_PRE_ROUTING; //called right
> after packet recieved, first hook in Netfilter
> nfho.pf = PF_INET; //IPV4 packets
> nfho.priority = NF_IP_PRI_FIRST; //set to highest
> priority over all other hook functions
> nf_register_hook(&nfho); //register hook
>
> return 0; //return 0 for
> success
> }
>
> //Called when module unloaded using 'rmmod'
> void cleanup_module()
> {
> nf_unregister_hook(&nfho); //cleanup –
> unregister hook
> }
>
>
> Here are the error message:
>
> $ make
> make -C /lib/modules/3.3.2-6.fc16.x86_64/build
> M=/home/fabio/Desktop/modules modules
> make[1]: Entering directory
> `/usr/src/kernels/3.3.2-6.fc16.x86_64'
> CC [M] /home/fabio/Desktop/modules/hello.o
> /home/fabio/Desktop/modules/hello.c: In function
> ‘init_module’:
> /home/fabio/Desktop/modules/hello.c:18:13: warning: assignment
> from incompatible pointer type [enabled by default]
> /home/fabio/Desktop/modules/hello.c:19:18: error:
> ‘NF_IP_PRE_ROUTING’ undeclared (first use in this function)
> /home/fabio/Desktop/modules/hello.c:19:18: note: each
> undeclared identifier is reported only once for each function
> it appears in
> make[2]: *** [/home/fabio/Desktop/modules/hello.o] Error 1
> make[1]: *** [_module_/home/fabio/Desktop/modules] Error 2
> make[1]: Leaving directory
> `/usr/src/kernels/3.3.2-6.fc16.x86_64'
> make: *** [all] Error 2
>
> _______________________________________________
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>
> Hi,
>
>
> You need to include header which defines "NF_IP_PRE_ROUTING"
>
>
> - Rohan
Hi,
But I have declared this header:
#include <linux/netfilter_ipv4.h>
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