1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
/* Shared library add-on to iptables to add masquerade support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <limits.h> /* INT_MAX in ip_tables.h */
#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/netfilter/nf_nat.h>
static void MASQUERADE_help(void)
{
printf(
"MASQUERADE target options:\n"
" --to-ports <port>[-<port>]\n"
" Port (range) to map to.\n"
" --random\n"
" Randomize source port.\n");
}
static const struct option MASQUERADE_opts[] = {
{ "to-ports", 1, NULL, '1' },
{ "random", 0, NULL, '2' },
{ .name = NULL }
};
static void MASQUERADE_init(struct xt_entry_target *t)
{
struct nf_nat_multi_range *mr = (struct nf_nat_multi_range *)t->data;
/* Actually, it's 0, but it's ignored at the moment. */
mr->rangesize = 1;
}
/* Parses ports */
static void
parse_ports(const char *arg, struct nf_nat_multi_range *mr)
{
char *end;
unsigned int port, maxport;
mr->range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
if (!xtables_strtoui(arg, &end, &port, 0, UINT16_MAX))
xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--to-ports", arg);
switch (*end) {
case '\0':
mr->range[0].min.tcp.port
= mr->range[0].max.tcp.port
= htons(port);
return;
case '-':
if (!xtables_strtoui(end + 1, NULL, &maxport, 0, UINT16_MAX))
break;
if (maxport < port)
break;
mr->range[0].min.tcp.port = htons(port);
mr->range[0].max.tcp.port = htons(maxport);
return;
default:
break;
}
xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--to-ports", arg);
}
static int MASQUERADE_parse(int c, char **argv, int invert, unsigned int *flags,
const void *e, struct xt_entry_target **target)
{
const struct ipt_entry *entry = e;
int portok;
struct nf_nat_multi_range *mr
= (struct nf_nat_multi_range *)(*target)->data;
if (entry->ip.proto == IPPROTO_TCP
|| entry->ip.proto == IPPROTO_UDP
|| entry->ip.proto == IPPROTO_SCTP
|| entry->ip.proto == IPPROTO_DCCP
|| entry->ip.proto == IPPROTO_ICMP)
portok = 1;
else
portok = 0;
switch (c) {
case '1':
if (!portok)
xtables_error(PARAMETER_PROBLEM,
"Need TCP, UDP, SCTP or DCCP with port specification");
if (xtables_check_inverse(optarg, &invert, NULL, 0, argv))
xtables_error(PARAMETER_PROBLEM,
"Unexpected `!' after --to-ports");
parse_ports(optarg, mr);
return 1;
case '2':
mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM;
return 1;
default:
return 0;
}
}
static void
MASQUERADE_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct nf_nat_multi_range *mr = (const void *)target->data;
const struct nf_nat_range *r = &mr->range[0];
if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
printf("masq ports: ");
printf("%hu", ntohs(r->min.tcp.port));
if (r->max.tcp.port != r->min.tcp.port)
printf("-%hu", ntohs(r->max.tcp.port));
printf(" ");
}
if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
printf("random ");
}
static void
MASQUERADE_save(const void *ip, const struct xt_entry_target *target)
{
const struct nf_nat_multi_range *mr = (const void *)target->data;
const struct nf_nat_range *r = &mr->range[0];
if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
printf("--to-ports %hu", ntohs(r->min.tcp.port));
if (r->max.tcp.port != r->min.tcp.port)
printf("-%hu", ntohs(r->max.tcp.port));
printf(" ");
}
if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
printf("--random ");
}
static struct xtables_target masquerade_tg_reg = {
.name = "MASQUERADE",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.size = XT_ALIGN(sizeof(struct nf_nat_multi_range)),
.userspacesize = XT_ALIGN(sizeof(struct nf_nat_multi_range)),
.help = MASQUERADE_help,
.init = MASQUERADE_init,
.parse = MASQUERADE_parse,
.print = MASQUERADE_print,
.save = MASQUERADE_save,
.extra_opts = MASQUERADE_opts,
};
void _init(void)
{
xtables_register_target(&masquerade_tg_reg);
}
|
