hi，
i have three PC
A ip = 192.168.2.249 vip = 192.168.2.99
B ip = 192.168.2.245 vip = 192.168.2.99 no arp
C ip = 192.168.2.19
A send package to 192.168.2.99 , then A get IP package from C and
change it's MAC and send to B. I find A can get C's IP package,
but it can't send out. I get the idea from ipvs's dr mode. I guess my
problem in function my_xmit, but i don't know why. Thanks.
======================
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/socket.h>/*PF_INET*/
#include <linux/netfilter_ipv4.h>/*NF_IP_PRE_FIRST*/
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/inet.h> /*in_aton()*/
#include <net/ip.h>
#include <net/tcp.h>
#include <linux/version.h>
#include <linux/module.h>
#define MAC_FMT "%02x:%02x:%02x:%02x:%02x:%02x"
#define MAC_ARG(x)
((u8*)(x))[0],((u8*)(x))[1],((u8*)(x))[2],((u8*)(x))[3],((u8*)(x))[4],((u8*)(x))[5]
MODULE_LICENSE("GPL");
MODULE_AUTHOR("bbo");
struct nf_hook_ops nfho;
struct nf_hook_ops nfout;
static char * vip="192.168.2.99";
static char server_mac[ETH_ALEN] = {0x90,0xFB,0xA6,0x03,0x06,0x61};
static char * client_ip = "192.168.2.16";
static char * rs_ip = "192.168.2.245";
#define MY_XMIT(pf, skb, rt) \
do { \
skb_forward_csum(skb); \
NF_HOOK(pf, NF_INET_LOCAL_OUT , (skb), NULL, \
(rt)->u.dst.dev, dst_output); \
} while (0)
void print_mac_buf(char * buf)
{
printk("DEST:" MAC_FMT "\n", MAC_ARG(buf));
printk("SOURCE:" MAC_FMT "\n", MAC_ARG(buf+6));
}
void print_mac(struct ethhdr* eth)
{
if(eth==NULL) return;
if(eth->h_source!=NULL) printk("SOURCE:" MAC_FMT "\n",
MAC_ARG(eth->h_source));
if(eth->h_dest!=NULL) printk("DEST:" MAC_FMT "\n", MAC_ARG(eth->h_dest));
}
static struct rtable * my_route(int daddr_ip,int rtos)
{
struct rtable *rt = NULL;/* Route to the other host */
struct flowi fl = {
.oif = 0,
.nl_u = {
.ip4_u = {
.daddr = daddr_ip,
.saddr = 0,
.tos = rtos, }
},
};
if(ip_route_output_key(&init_net, &rt, &fl))
return NULL;
if(rt)
{
char * buf;
struct hh_cache * hh = rt->u.dst.hh;
if(hh)
{
buf = hh->hh_data;
print_mac_buf(buf+2);
}
}
return rt;
}
int my_xmit(struct sk_buff *skb, int daddr_ip)
{
struct rtable *rt; /* Route to the other host */
struct iphdr *iph = ip_hdr(skb);
int mtu;
rt = my_route(daddr_ip, RT_TOS(iph->tos));
if(rt == NULL) return 0;
/*
* Call ip_send_check because we are not sure it is called
* after ip_defrag. Is copy-on-write needed?
*/
if (unlikely((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)) {
ip_rt_put(rt);
return 1;
}
ip_send_check(ip_hdr(skb));
/* drop old route */
skb_dst_drop(skb);
skb_dst_set(skb, &rt->u.dst);
/* Another hack: avoid icmp_send in ip_fragment */
skb->local_df = 1;
MY_XMIT(NFPROTO_IPV4, skb, rt);
return 1;
}
unsigned int checksum(unsigned int hooknum,
struct sk_buff *__skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb;
struct net_device *dev;
struct iphdr *iph;
struct tcphdr *tcph;
int tot_len;
int iph_len;
int tcph_len;
int ret;
skb = __skb;
if(skb == NULL) return NF_ACCEPT;
iph = ip_hdr(skb);
if(iph == NULL) return NF_ACCEPT;
if((iph->daddr == in_aton(vip)) && (iph->saddr == in_aton(client_ip)))
{
if(my_xmit(skb,in_aton(rs_ip)))
{
printk ("route OK\n");
return NF_STOLEN;
}
else
{
printk ("route false\n");
}
}
return NF_ACCEPT;
}
unsigned int output(unsigned int hooknum,
struct sk_buff *__skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb;
struct net_device *dev;
struct iphdr *iph;
struct tcphdr *tcph;
int tot_len;
int iph_len;
int tcph_len;
int ret;
skb = __skb;
if(skb == NULL) return NF_ACCEPT;
iph = ip_hdr(skb);
if(iph == NULL) return NF_ACCEPT;
if((iph->daddr == in_aton(vip)) && (iph->saddr == in_aton(client_ip)))
{
printk ("In output\n");
}
return NF_ACCEPT;
}
static int __init filter_init(void)
{
int ret;
nfho.hook = checksum;
nfho.pf = AF_INET;
// nfho.hooknum = NF_INET_PRE_ROUTING;
nfho.hooknum = NF_INET_LOCAL_IN;
// nfho.hooknum = NF_IP_PRE_ROUTING;
nfho.priority = NF_IP_PRI_FIRST;
nfout.hook = output;
nfout.pf = AF_INET;
nfout.hooknum = NF_INET_POST_ROUTING;
nfho.priority = NF_IP_PRI_FIRST;
printk ("Hello,init forward~~~~~~~.\n");
ret = nf_register_hook(&nfho);
if(ret < 0)
{
printk("%s\n", "can't modify skb hook!");
return ret;
}
return 0;
}
static void filter_fini(void)
{
printk ("Hello,remove forward~~~~~~~.\n");
nf_unregister_hook(&nfho);
}
module_init(filter_init);
module_exit(filter_fini);
--
Jianzhang Peng
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