1 /* Shared library add-on to iptables to add redirect support. */
8 #include <linux/netfilter_ipv4/ip_tables.h>
9 #include <linux/netfilter/nf_nat.h>
11 #define IPT_REDIRECT_OPT_DEST 0x01
12 #define IPT_REDIRECT_OPT_RANDOM 0x02
14 /* Function which prints out usage message. */
19 "REDIRECT v%s options:\n"
20 " --to-ports <port>[-<port>]\n"
21 " Port (range) to map to.\n\n",
25 static struct option opts[] = {
26 { "to-ports", 1, 0, '1' },
27 { "random", 1, 0, '2' },
31 /* Initialize the target. */
33 init(struct ipt_entry_target *t, unsigned int *nfcache)
35 struct ip_nat_multi_range *mr = (struct ip_nat_multi_range *)t->data;
37 /* Actually, it's 0, but it's ignored at the moment. */
44 parse_ports(const char *arg, struct ip_nat_multi_range *mr)
49 mr->range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
52 exit_error(PARAMETER_PROBLEM, "IP address not permitted\n");
55 if (port == 0 || port > 65535)
56 exit_error(PARAMETER_PROBLEM, "Port `%s' not valid\n", arg);
58 dash = strchr(arg, '-');
60 mr->range[0].min.tcp.port
61 = mr->range[0].max.tcp.port
66 maxport = atoi(dash + 1);
67 if (maxport == 0 || maxport > 65535)
68 exit_error(PARAMETER_PROBLEM,
69 "Port `%s' not valid\n", dash+1);
71 /* People are stupid. */
72 exit_error(PARAMETER_PROBLEM,
73 "Port range `%s' funky\n", arg);
74 mr->range[0].min.tcp.port = htons(port);
75 mr->range[0].max.tcp.port = htons(maxport);
79 /* Function which parses command options; returns true if it
82 parse(int c, char **argv, int invert, unsigned int *flags,
83 const struct ipt_entry *entry,
84 struct ipt_entry_target **target)
86 struct ip_nat_multi_range *mr
87 = (struct ip_nat_multi_range *)(*target)->data;
90 if (entry->ip.proto == IPPROTO_TCP
91 || entry->ip.proto == IPPROTO_UDP
92 || entry->ip.proto == IPPROTO_ICMP)
100 exit_error(PARAMETER_PROBLEM,
101 "Need TCP or UDP with port specification");
103 if (check_inverse(optarg, &invert, NULL, 0))
104 exit_error(PARAMETER_PROBLEM,
105 "Unexpected `!' after --to-ports");
107 parse_ports(optarg, mr);
108 if (*flags & IPT_REDIRECT_OPT_RANDOM)
109 mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM;
110 *flags |= IPT_REDIRECT_OPT_DEST;
114 if (*flags & IPT_REDIRECT_OPT_DEST) {
115 mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM;
116 *flags |= IPT_REDIRECT_OPT_RANDOM;
118 *flags |= IPT_REDIRECT_OPT_RANDOM;
126 /* Final check; don't care. */
127 static void final_check(unsigned int flags)
131 /* Prints out the targinfo. */
133 print(const struct ipt_ip *ip,
134 const struct ipt_entry_target *target,
137 struct ip_nat_multi_range *mr
138 = (struct ip_nat_multi_range *)target->data;
139 struct ip_nat_range *r = &mr->range[0];
141 if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
142 printf("redir ports ");
143 printf("%hu", ntohs(r->min.tcp.port));
144 if (r->max.tcp.port != r->min.tcp.port)
145 printf("-%hu", ntohs(r->max.tcp.port));
147 if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM)
152 /* Saves the union ipt_targinfo in parsable form to stdout. */
154 save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
156 struct ip_nat_multi_range *mr
157 = (struct ip_nat_multi_range *)target->data;
158 struct ip_nat_range *r = &mr->range[0];
160 if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
161 printf("--to-ports ");
162 printf("%hu", ntohs(r->min.tcp.port));
163 if (r->max.tcp.port != r->min.tcp.port)
164 printf("-%hu", ntohs(r->max.tcp.port));
166 if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM)
171 static struct iptables_target redir = {
174 .version = IPTABLES_VERSION,
175 .size = IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
176 .userspacesize = IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
180 .final_check = &final_check,
188 register_target(&redir);