1 /* Shared library add-on to iptables to add masquerade support. */
8 #include <limits.h> /* INT_MAX in ip_tables.h */
9 #include <linux/netfilter_ipv4/ip_tables.h>
10 #include <net/netfilter/nf_nat.h>
12 static void MASQUERADE_help(void)
15 "MASQUERADE target options:\n"
16 " --to-ports <port>[-<port>]\n"
17 " Port (range) to map to.\n"
19 " Randomize source port.\n");
22 static const struct option MASQUERADE_opts[] = {
23 { "to-ports", 1, NULL, '1' },
24 { "random", 0, NULL, '2' },
28 static void MASQUERADE_init(struct xt_entry_target *t)
30 struct nf_nat_multi_range *mr = (struct nf_nat_multi_range *)t->data;
32 /* Actually, it's 0, but it's ignored at the moment. */
39 parse_ports(const char *arg, struct nf_nat_multi_range *mr)
42 unsigned int port, maxport;
44 mr->range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
46 if (!xtables_strtoui(arg, &end, &port, 0, UINT16_MAX))
47 xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--to-ports", arg);
51 mr->range[0].min.tcp.port
52 = mr->range[0].max.tcp.port
56 if (!xtables_strtoui(end + 1, NULL, &maxport, 0, UINT16_MAX))
62 mr->range[0].min.tcp.port = htons(port);
63 mr->range[0].max.tcp.port = htons(maxport);
68 xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--to-ports", arg);
71 static int MASQUERADE_parse(int c, char **argv, int invert, unsigned int *flags,
72 const void *e, struct xt_entry_target **target)
74 const struct ipt_entry *entry = e;
76 struct nf_nat_multi_range *mr
77 = (struct nf_nat_multi_range *)(*target)->data;
79 if (entry->ip.proto == IPPROTO_TCP
80 || entry->ip.proto == IPPROTO_UDP
81 || entry->ip.proto == IPPROTO_SCTP
82 || entry->ip.proto == IPPROTO_DCCP
83 || entry->ip.proto == IPPROTO_ICMP)
91 xtables_error(PARAMETER_PROBLEM,
92 "Need TCP, UDP, SCTP or DCCP with port specification");
94 if (xtables_check_inverse(optarg, &invert, NULL, 0, argv))
95 xtables_error(PARAMETER_PROBLEM,
96 "Unexpected `!' after --to-ports");
98 parse_ports(optarg, mr);
102 mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM;
111 MASQUERADE_print(const void *ip, const struct xt_entry_target *target,
114 const struct nf_nat_multi_range *mr = (const void *)target->data;
115 const struct nf_nat_range *r = &mr->range[0];
117 if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
118 printf("masq ports: ");
119 printf("%hu", ntohs(r->min.tcp.port));
120 if (r->max.tcp.port != r->min.tcp.port)
121 printf("-%hu", ntohs(r->max.tcp.port));
125 if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
130 MASQUERADE_save(const void *ip, const struct xt_entry_target *target)
132 const struct nf_nat_multi_range *mr = (const void *)target->data;
133 const struct nf_nat_range *r = &mr->range[0];
135 if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
136 printf("--to-ports %hu", ntohs(r->min.tcp.port));
137 if (r->max.tcp.port != r->min.tcp.port)
138 printf("-%hu", ntohs(r->max.tcp.port));
142 if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
146 static struct xtables_target masquerade_tg_reg = {
147 .name = "MASQUERADE",
148 .version = XTABLES_VERSION,
149 .family = NFPROTO_IPV4,
150 .size = XT_ALIGN(sizeof(struct nf_nat_multi_range)),
151 .userspacesize = XT_ALIGN(sizeof(struct nf_nat_multi_range)),
152 .help = MASQUERADE_help,
153 .init = MASQUERADE_init,
154 .parse = MASQUERADE_parse,
155 .print = MASQUERADE_print,
156 .save = MASQUERADE_save,
157 .extra_opts = MASQUERADE_opts,
162 xtables_register_target(&masquerade_tg_reg);