| /* NETMAP - static NAT mapping of IP network addresses (1:1). |
| * The mapping can be applied to source (POSTROUTING), |
| * destination (PREROUTING), or both (with separate rules). |
| */ |
| |
| /* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| |
| #include <linux/ip.h> |
| #include <linux/module.h> |
| #include <linux/netdevice.h> |
| #include <linux/netfilter.h> |
| #include <linux/netfilter_ipv4.h> |
| #ifdef CONFIG_NF_NAT_NEEDED |
| #include <net/netfilter/nf_nat_rule.h> |
| #else |
| #include <linux/netfilter_ipv4/ip_nat_rule.h> |
| #endif |
| |
| #define MODULENAME "NETMAP" |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>"); |
| MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target"); |
| |
| #if 0 |
| #define DEBUGP printk |
| #else |
| #define DEBUGP(format, args...) |
| #endif |
| |
| static int |
| check(const char *tablename, |
| const void *e, |
| const struct xt_target *target, |
| void *targinfo, |
| unsigned int hook_mask) |
| { |
| const struct ip_nat_multi_range_compat *mr = targinfo; |
| |
| if (!(mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)) { |
| DEBUGP(MODULENAME":check: bad MAP_IPS.\n"); |
| return 0; |
| } |
| if (mr->rangesize != 1) { |
| DEBUGP(MODULENAME":check: bad rangesize %u.\n", mr->rangesize); |
| return 0; |
| } |
| return 1; |
| } |
| |
| static unsigned int |
| target(struct sk_buff **pskb, |
| const struct net_device *in, |
| const struct net_device *out, |
| unsigned int hooknum, |
| const struct xt_target *target, |
| const void *targinfo) |
| { |
| struct ip_conntrack *ct; |
| enum ip_conntrack_info ctinfo; |
| __be32 new_ip, netmask; |
| const struct ip_nat_multi_range_compat *mr = targinfo; |
| struct ip_nat_range newrange; |
| |
| IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING |
| || hooknum == NF_IP_POST_ROUTING |
| || hooknum == NF_IP_LOCAL_OUT); |
| ct = ip_conntrack_get(*pskb, &ctinfo); |
| |
| netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip); |
| |
| if (hooknum == NF_IP_PRE_ROUTING || hooknum == NF_IP_LOCAL_OUT) |
| new_ip = (*pskb)->nh.iph->daddr & ~netmask; |
| else |
| new_ip = (*pskb)->nh.iph->saddr & ~netmask; |
| new_ip |= mr->range[0].min_ip & netmask; |
| |
| newrange = ((struct ip_nat_range) |
| { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS, |
| new_ip, new_ip, |
| mr->range[0].min, mr->range[0].max }); |
| |
| /* Hand modified range to generic setup. */ |
| return ip_nat_setup_info(ct, &newrange, hooknum); |
| } |
| |
| static struct ipt_target target_module = { |
| .name = MODULENAME, |
| .target = target, |
| .targetsize = sizeof(struct ip_nat_multi_range_compat), |
| .table = "nat", |
| .hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_POST_ROUTING) | |
| (1 << NF_IP_LOCAL_OUT), |
| .checkentry = check, |
| .me = THIS_MODULE |
| }; |
| |
| static int __init ipt_netmap_init(void) |
| { |
| return ipt_register_target(&target_module); |
| } |
| |
| static void __exit ipt_netmap_fini(void) |
| { |
| ipt_unregister_target(&target_module); |
| } |
| |
| module_init(ipt_netmap_init); |
| module_exit(ipt_netmap_fini); |