From: Patrick McHardy <kaber@xxxxxxxxx>
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
extensions/libip6t_MASQUERADE.c | 150 +++++++++++++++++++++++++++++++++++++
extensions/libip6t_MASQUERADE.man | 30 ++++++++
include/linux/netfilter/nf_nat.h | 8 ++
3 files changed, 188 insertions(+), 0 deletions(-)
create mode 100644 extensions/libip6t_MASQUERADE.c
create mode 100644 extensions/libip6t_MASQUERADE.man
diff --git a/extensions/libip6t_MASQUERADE.c b/extensions/libip6t_MASQUERADE.c
new file mode 100644
index 0000000..eb9213e
--- /dev/null
+++ b/extensions/libip6t_MASQUERADE.c
@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2011 Patrick McHardy <kaber@xxxxxxxxx>
+ *
+ * Based on Rusty Russell's IPv4 MASQUERADE target. Development of IPv6 NAT
+ * funded by Astaro.
+ */
+
+#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_ipv6/ip6_tables.h>
+#include <linux/netfilter/nf_nat.h>
+
+enum {
+ O_TO_PORTS = 0,
+ O_RANDOM,
+};
+
+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 xt_option_entry MASQUERADE_opts[] = {
+ {.name = "to-ports", .id = O_TO_PORTS, .type = XTTYPE_STRING},
+ {.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
+ XTOPT_TABLEEND,
+};
+
+/* Parses ports */
+static void
+parse_ports(const char *arg, struct nf_nat_range *r)
+{
+ char *end;
+ unsigned int port, maxport;
+
+ r->flags |= NF_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':
+ r->min_proto.tcp.port
+ = r->max_proto.tcp.port
+ = htons(port);
+ return;
+ case '-':
+ if (!xtables_strtoui(end + 1, NULL, &maxport, 0, UINT16_MAX))
+ break;
+
+ if (maxport < port)
+ break;
+
+ r->min_proto.tcp.port = htons(port);
+ r->max_proto.tcp.port = htons(maxport);
+ return;
+ default:
+ break;
+ }
+ xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--to-ports", arg);
+}
+
+static void MASQUERADE_parse(struct xt_option_call *cb)
+{
+ const struct ip6t_entry *entry = cb->xt_entry;
+ struct nf_nat_range *r = cb->data;
+ int portok;
+
+ if (entry->ipv6.proto == IPPROTO_TCP ||
+ entry->ipv6.proto == IPPROTO_UDP ||
+ entry->ipv6.proto == IPPROTO_SCTP ||
+ entry->ipv6.proto == IPPROTO_DCCP ||
+ entry->ipv6.proto == IPPROTO_ICMP)
+ portok = 1;
+ else
+ portok = 0;
+
+ xtables_option_parse(cb);
+ switch (cb->entry->id) {
+ case O_TO_PORTS:
+ if (!portok)
+ xtables_error(PARAMETER_PROBLEM,
+ "Need TCP, UDP, SCTP or DCCP with port specification");
+ parse_ports(cb->arg, r);
+ break;
+ case O_RANDOM:
+ r->flags |= NF_NAT_RANGE_PROTO_RANDOM;
+ break;
+ }
+}
+
+static void
+MASQUERADE_print(const void *ip, const struct xt_entry_target *target,
+ int numeric)
+{
+ const struct nf_nat_range *r = (const void *)target->data;
+
+ if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
+ printf(" masq ports: ");
+ printf("%hu", ntohs(r->min_proto.tcp.port));
+ if (r->max_proto.tcp.port != r->min_proto.tcp.port)
+ printf("-%hu", ntohs(r->max_proto.tcp.port));
+ }
+
+ if (r->flags & NF_NAT_RANGE_PROTO_RANDOM)
+ printf(" random");
+}
+
+static void
+MASQUERADE_save(const void *ip, const struct xt_entry_target *target)
+{
+ const struct nf_nat_range *r = (const void *)target->data;
+
+ if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
+ printf(" --to-ports %hu", ntohs(r->min_proto.tcp.port));
+ if (r->max_proto.tcp.port != r->min_proto.tcp.port)
+ printf("-%hu", ntohs(r->max_proto.tcp.port));
+ }
+
+ if (r->flags & NF_NAT_RANGE_PROTO_RANDOM)
+ printf(" --random");
+}
+
+static struct xtables_target masquerade_tg_reg = {
+ .name = "MASQUERADE",
+ .version = XTABLES_VERSION,
+ .family = NFPROTO_IPV6,
+ .size = XT_ALIGN(sizeof(struct nf_nat_range)),
+ .userspacesize = XT_ALIGN(sizeof(struct nf_nat_range)),
+ .help = MASQUERADE_help,
+ .x6_parse = MASQUERADE_parse,
+ .print = MASQUERADE_print,
+ .save = MASQUERADE_save,
+ .x6_options = MASQUERADE_opts,
+};
+
+void _init(void)
+{
+ xtables_register_target(&masquerade_tg_reg);
+}
diff --git a/extensions/libip6t_MASQUERADE.man b/extensions/libip6t_MASQUERADE.man
new file mode 100644
index 0000000..c63d826
--- /dev/null
+++ b/extensions/libip6t_MASQUERADE.man
@@ -0,0 +1,30 @@
+This target is only valid in the
+.B nat
+table, in the
+.B POSTROUTING
+chain. It should only be used with dynamically assigned IPv6 (dialup)
+connections: if you have a static IP address, you should use the SNAT
+target. Masquerading is equivalent to specifying a mapping to the IP
+address of the interface the packet is going out, but also has the
+effect that connections are
+.I forgotten
+when the interface goes down. This is the correct behavior when the
+next dialup is unlikely to have the same interface address (and hence
+any established connections are lost anyway).
+.TP
+\fB\-\-to\-ports\fP \fIport\fP[\fB\-\fP\fIport\fP]
+This specifies a range of source ports to use, overriding the default
+.B SNAT
+source port-selection heuristics (see above). This is only valid
+if the rule also specifies
+\fB\-p tcp\fP
+or
+\fB\-p udp\fP.
+.TP
+\fB\-\-random\fP
+Randomize source port mapping
+If option
+\fB\-\-random\fP
+is used then port mapping will be randomized.
+.RS
+.PP
diff --git a/include/linux/netfilter/nf_nat.h b/include/linux/netfilter/nf_nat.h
index 8df2d13..bf0cc37 100644
--- a/include/linux/netfilter/nf_nat.h
+++ b/include/linux/netfilter/nf_nat.h
@@ -22,4 +22,12 @@ struct nf_nat_ipv4_multi_range_compat {
struct nf_nat_ipv4_range range[1];
};
+struct nf_nat_range {
+ unsigned int flags;
+ union nf_inet_addr min_addr;
+ union nf_inet_addr max_addr;
+ union nf_conntrack_man_proto min_proto;
+ union nf_conntrack_man_proto max_proto;
+};
+
#endif /* _NETFILTER_NF_NAT_H */
--
1.7.1
--
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