1 /* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License version 2 as
5 * published by the Free Software Foundation.
9 * Thu 21 Mar 2002 Harald Welte <laforge@gnumonks.org>
10 * - Port to newnat API
12 * This module currently supports DNAT:
13 * iptables -t nat -A PREROUTING -d x.x.x.x -j DNAT --to-dest x.x.x.y
16 * iptables -t nat -A POSTROUTING { -j MASQUERADE , -j SNAT --to-source x.x.x.x }
18 * It has not been tested with
19 * -j SNAT --to-source x.x.x.x-x.x.x.y since I only have one external ip
20 * If you do test this please let me know if it works or not.
24 #include <linux/module.h>
25 #include <linux/netfilter_ipv4.h>
27 #include <linux/udp.h>
29 #include <linux/netfilter.h>
30 #include <linux/netfilter_ipv4/ip_tables.h>
31 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
32 #include <linux/netfilter_ipv4/ip_conntrack_tftp.h>
33 #include <linux/netfilter_ipv4/ip_nat_helper.h>
34 #include <linux/netfilter_ipv4/ip_nat_rule.h>
36 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
37 MODULE_DESCRIPTION("tftp NAT helper");
38 MODULE_LICENSE("GPL");
42 static int ports[MAX_PORTS];
43 static int ports_c = 0;
45 MODULE_PARM(ports,"1-" __MODULE_STRING(MAX_PORTS) "i");
46 MODULE_PARM_DESC(ports, "port numbers of tftp servers");
50 #define DEBUGP(format, args...) printk("%s:%s:" format, \
51 __FILE__, __FUNCTION__ , ## args)
53 #define DEBUGP(format, args...)
56 tftp_nat_help(struct ip_conntrack *ct,
57 struct ip_conntrack_expect *exp,
58 struct ip_nat_info *info,
59 enum ip_conntrack_info ctinfo,
61 struct sk_buff **pskb)
63 int dir = CTINFO2DIR(ctinfo);
65 struct ip_conntrack_tuple repl;
67 if (!((hooknum == NF_IP_POST_ROUTING && dir == IP_CT_DIR_ORIGINAL)
68 || (hooknum == NF_IP_PRE_ROUTING && dir == IP_CT_DIR_REPLY)))
72 DEBUGP("no conntrack expectation to modify\n");
76 if (skb_copy_bits(*pskb, (*pskb)->nh.iph->ihl*4+sizeof(struct udphdr),
77 &tftph, sizeof(tftph)) != 0)
80 switch (ntohs(tftph.opcode)) {
81 /* RRQ and WRQ works the same way */
82 case TFTP_OPCODE_READ:
83 case TFTP_OPCODE_WRITE:
84 repl = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
86 DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
87 DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
88 DEBUGP("expecting: ");
90 DUMP_TUPLE(&exp->mask);
91 ip_conntrack_change_expect(exp, &repl);
94 DEBUGP("Unknown opcode\n");
101 tftp_nat_expected(struct sk_buff **pskb,
102 unsigned int hooknum,
103 struct ip_conntrack *ct,
104 struct ip_nat_info *info)
106 const struct ip_conntrack *master = ct->master->expectant;
107 const struct ip_conntrack_tuple *orig =
108 &master->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
109 struct ip_nat_multi_range mr;
111 const struct ip_conntrack_tuple *repl =
112 &master->tuplehash[IP_CT_DIR_REPLY].tuple;
115 if (skb_copy_bits(*pskb,(*pskb)->nh.iph->ihl*4,&udph,sizeof(udph))!=0)
120 IP_NF_ASSERT(master);
121 IP_NF_ASSERT(!(info->initialized & (1 << HOOK2MANIP(hooknum))));
124 mr.range[0].flags = IP_NAT_RANGE_MAP_IPS;
126 if (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC) {
127 mr.range[0].min_ip = mr.range[0].max_ip = orig->dst.ip;
128 DEBUGP("orig: %u.%u.%u.%u:%u <-> %u.%u.%u.%u:%u "
129 "newsrc: %u.%u.%u.%u\n",
130 NIPQUAD((*pskb)->nh.iph->saddr), ntohs(udph.source),
131 NIPQUAD((*pskb)->nh.iph->daddr), ntohs(udph.dest),
132 NIPQUAD(orig->dst.ip));
134 mr.range[0].min_ip = mr.range[0].max_ip = orig->src.ip;
135 mr.range[0].min.udp.port = mr.range[0].max.udp.port =
136 orig->src.u.udp.port;
137 mr.range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
139 DEBUGP("orig: %u.%u.%u.%u:%u <-> %u.%u.%u.%u:%u "
140 "newdst: %u.%u.%u.%u:%u\n",
141 NIPQUAD((*pskb)->nh.iph->saddr), ntohs(udph.source),
142 NIPQUAD((*pskb)->nh.iph->daddr), ntohs(udph.dest),
143 NIPQUAD(orig->src.ip), ntohs(orig->src.u.udp.port));
146 return ip_nat_setup_info(ct,&mr,hooknum);
149 static struct ip_nat_helper tftp[MAX_PORTS];
150 static char tftp_names[MAX_PORTS][10];
152 static void fini(void)
156 for (i = 0 ; i < ports_c; i++) {
157 DEBUGP("unregistering helper for port %d\n", ports[i]);
158 ip_nat_helper_unregister(&tftp[i]);
162 static int __init init(void)
168 ports[0] = TFTP_PORT;
170 for (i = 0 ; (i < MAX_PORTS) && ports[i] ; i++) {
171 memset(&tftp[i], 0, sizeof(struct ip_nat_helper));
173 tftp[i].tuple.dst.protonum = IPPROTO_UDP;
174 tftp[i].tuple.src.u.udp.port = htons(ports[i]);
175 tftp[i].mask.dst.protonum = 0xFFFF;
176 tftp[i].mask.src.u.udp.port = 0xFFFF;
177 tftp[i].help = tftp_nat_help;
179 tftp[i].me = THIS_MODULE;
180 tftp[i].expect = tftp_nat_expected;
182 tmpname = &tftp_names[i][0];
183 if (ports[i] == TFTP_PORT)
184 sprintf(tmpname, "tftp");
186 sprintf(tmpname, "tftp-%d", i);
187 tftp[i].name = tmpname;
189 DEBUGP("ip_nat_tftp: registering for port %d: name %s\n",
190 ports[i], tftp[i].name);
191 ret = ip_nat_helper_register(&tftp[i]);
194 printk("ip_nat_tftp: unable to register for port %d\n",