2eb0f624b7
This is a patch proposal to support shifted ranges in portmaps. (i.e. tcp/udp incoming port 5000-5100 on WAN redirected to LAN 192.168.1.5:2000-2100) Currently DNAT only works for single port or identical port ranges. (i.e. ports 5000-5100 on WAN interface redirected to a LAN host while original destination port is not altered) When different port ranges are configured, either 'random' mode should be used, or else all incoming connections are mapped onto the first port in the redirect range. (in described example WAN:5000-5100 will all be mapped to 192.168.1.5:2000) This patch introduces a new mode indicated by flag NF_NAT_RANGE_PROTO_OFFSET which uses a base port value to calculate an offset with the destination port present in the incoming stream. That offset is then applied as index within the redirect port range (index modulo rangewidth to handle range overflow). In described example the base port would be 5000. An incoming stream with destination port 5004 would result in an offset value 4 which means that the NAT'ed stream will be using destination port 2004. Other possibilities include deterministic mapping of larger or multiple ranges to a smaller range : WAN:5000-5999 -> LAN:5000-5099 (maps WAN port 5*xx to port 51xx) This patch does not change any current behavior. It just adds new NAT proto range functionality which must be selected via the specific flag when intended to use. A patch for iptables (libipt_DNAT.c + libip6t_DNAT.c) will also be proposed which makes this functionality immediately available. Signed-off-by: Thierry Du Tre <thierry@dtsystems.be> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
122 lines
3.3 KiB
C
122 lines
3.3 KiB
C
/*
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* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
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* NAT funded by Astaro.
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*/
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#include <linux/if.h>
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#include <linux/inetdevice.h>
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#include <linux/ip.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <linux/netfilter.h>
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#include <linux/types.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter/x_tables.h>
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#include <net/addrconf.h>
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#include <net/checksum.h>
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#include <net/protocol.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_redirect.h>
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static unsigned int
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redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
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{
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return nf_nat_redirect_ipv6(skb, par->targinfo, xt_hooknum(par));
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}
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static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_range2 *range = par->targinfo;
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if (range->flags & NF_NAT_RANGE_MAP_IPS)
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return -EINVAL;
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return nf_ct_netns_get(par->net, par->family);
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}
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static void redirect_tg_destroy(const struct xt_tgdtor_param *par)
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{
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nf_ct_netns_put(par->net, par->family);
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}
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/* FIXME: Take multiple ranges --RR */
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static int redirect_tg4_check(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
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if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
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pr_debug("bad MAP_IPS.\n");
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return -EINVAL;
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}
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if (mr->rangesize != 1) {
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pr_debug("bad rangesize %u.\n", mr->rangesize);
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return -EINVAL;
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}
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return nf_ct_netns_get(par->net, par->family);
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}
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static unsigned int
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redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
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{
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return nf_nat_redirect_ipv4(skb, par->targinfo, xt_hooknum(par));
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}
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static struct xt_target redirect_tg_reg[] __read_mostly = {
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{
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.name = "REDIRECT",
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.family = NFPROTO_IPV6,
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.revision = 0,
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.table = "nat",
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.checkentry = redirect_tg6_checkentry,
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.destroy = redirect_tg_destroy,
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.target = redirect_tg6,
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.targetsize = sizeof(struct nf_nat_range),
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_OUT),
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.me = THIS_MODULE,
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},
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{
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.name = "REDIRECT",
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.family = NFPROTO_IPV4,
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.revision = 0,
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.table = "nat",
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.target = redirect_tg4,
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.checkentry = redirect_tg4_check,
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.destroy = redirect_tg_destroy,
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.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_OUT),
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.me = THIS_MODULE,
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},
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};
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static int __init redirect_tg_init(void)
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{
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return xt_register_targets(redirect_tg_reg,
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ARRAY_SIZE(redirect_tg_reg));
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}
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static void __exit redirect_tg_exit(void)
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{
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xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg));
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}
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module_init(redirect_tg_init);
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module_exit(redirect_tg_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
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MODULE_ALIAS("ip6t_REDIRECT");
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MODULE_ALIAS("ipt_REDIRECT");
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