1 /* NETMAP - static NAT mapping of IP network addresses (1:1).
2 * The mapping can be applied to source (POSTROUTING),
3 * destination (PREROUTING), or both (with separate rules).
6 /* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
14 #include <linux/module.h>
15 #include <linux/netdevice.h>
16 #include <linux/netfilter.h>
17 #include <linux/netfilter_ipv4.h>
18 #include <linux/netfilter/x_tables.h>
19 #include <net/netfilter/nf_nat_rule.h>
21 MODULE_LICENSE("GPL");
22 MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>");
23 MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target");
26 check(const char *tablename
,
28 const struct xt_target
*target
,
30 unsigned int hook_mask
)
32 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
34 if (!(mr
->range
[0].flags
& IP_NAT_RANGE_MAP_IPS
)) {
35 pr_debug("NETMAP:check: bad MAP_IPS.\n");
38 if (mr
->rangesize
!= 1) {
39 pr_debug("NETMAP:check: bad rangesize %u.\n", mr
->rangesize
);
46 target(struct sk_buff
*skb
,
47 const struct net_device
*in
,
48 const struct net_device
*out
,
50 const struct xt_target
*target
,
54 enum ip_conntrack_info ctinfo
;
55 __be32 new_ip
, netmask
;
56 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
57 struct nf_nat_range newrange
;
59 NF_CT_ASSERT(hooknum
== NF_INET_PRE_ROUTING
60 || hooknum
== NF_INET_POST_ROUTING
61 || hooknum
== NF_INET_LOCAL_OUT
);
62 ct
= nf_ct_get(skb
, &ctinfo
);
64 netmask
= ~(mr
->range
[0].min_ip
^ mr
->range
[0].max_ip
);
66 if (hooknum
== NF_INET_PRE_ROUTING
|| hooknum
== NF_INET_LOCAL_OUT
)
67 new_ip
= ip_hdr(skb
)->daddr
& ~netmask
;
69 new_ip
= ip_hdr(skb
)->saddr
& ~netmask
;
70 new_ip
|= mr
->range
[0].min_ip
& netmask
;
72 newrange
= ((struct nf_nat_range
)
73 { mr
->range
[0].flags
| IP_NAT_RANGE_MAP_IPS
,
75 mr
->range
[0].min
, mr
->range
[0].max
});
77 /* Hand modified range to generic setup. */
78 return nf_nat_setup_info(ct
, &newrange
, hooknum
);
81 static struct xt_target target_module __read_mostly
= {
85 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
87 .hooks
= (1 << NF_INET_PRE_ROUTING
) |
88 (1 << NF_INET_POST_ROUTING
) |
89 (1 << NF_INET_LOCAL_OUT
),
94 static int __init
ipt_netmap_init(void)
96 return xt_register_target(&target_module
);
99 static void __exit
ipt_netmap_fini(void)
101 xt_unregister_target(&target_module
);
104 module_init(ipt_netmap_init
);
105 module_exit(ipt_netmap_fini
);