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 #define MODULENAME "NETMAP"
22 MODULE_LICENSE("GPL");
23 MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>");
24 MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target");
29 #define DEBUGP(format, args...)
33 check(const char *tablename
,
35 const struct xt_target
*target
,
37 unsigned int hook_mask
)
39 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
41 if (!(mr
->range
[0].flags
& IP_NAT_RANGE_MAP_IPS
)) {
42 DEBUGP(MODULENAME
":check: bad MAP_IPS.\n");
45 if (mr
->rangesize
!= 1) {
46 DEBUGP(MODULENAME
":check: bad rangesize %u.\n", mr
->rangesize
);
53 target(struct sk_buff
*skb
,
54 const struct net_device
*in
,
55 const struct net_device
*out
,
57 const struct xt_target
*target
,
61 enum ip_conntrack_info ctinfo
;
62 __be32 new_ip
, netmask
;
63 const struct nf_nat_multi_range_compat
*mr
= targinfo
;
64 struct nf_nat_range newrange
;
66 NF_CT_ASSERT(hooknum
== NF_IP_PRE_ROUTING
67 || hooknum
== NF_IP_POST_ROUTING
68 || hooknum
== NF_IP_LOCAL_OUT
);
69 ct
= nf_ct_get(skb
, &ctinfo
);
71 netmask
= ~(mr
->range
[0].min_ip
^ mr
->range
[0].max_ip
);
73 if (hooknum
== NF_IP_PRE_ROUTING
|| hooknum
== NF_IP_LOCAL_OUT
)
74 new_ip
= ip_hdr(skb
)->daddr
& ~netmask
;
76 new_ip
= ip_hdr(skb
)->saddr
& ~netmask
;
77 new_ip
|= mr
->range
[0].min_ip
& netmask
;
79 newrange
= ((struct nf_nat_range
)
80 { mr
->range
[0].flags
| IP_NAT_RANGE_MAP_IPS
,
82 mr
->range
[0].min
, mr
->range
[0].max
});
84 /* Hand modified range to generic setup. */
85 return nf_nat_setup_info(ct
, &newrange
, hooknum
);
88 static struct xt_target target_module
= {
92 .targetsize
= sizeof(struct nf_nat_multi_range_compat
),
94 .hooks
= (1 << NF_IP_PRE_ROUTING
) | (1 << NF_IP_POST_ROUTING
) |
95 (1 << NF_IP_LOCAL_OUT
),
100 static int __init
ipt_netmap_init(void)
102 return xt_register_target(&target_module
);
105 static void __exit
ipt_netmap_fini(void)
107 xt_unregister_target(&target_module
);
110 module_init(ipt_netmap_init
);
111 module_exit(ipt_netmap_fini
);