1 /* Amanda extension for TCP NAT alteration.
2 * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
3 * based on a copy of HW's ip_nat_irc.c as well as other modules
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/skbuff.h>
14 #include <linux/udp.h>
16 #include <net/netfilter/nf_nat_helper.h>
17 #include <net/netfilter/nf_nat_rule.h>
18 #include <net/netfilter/nf_conntrack_helper.h>
19 #include <net/netfilter/nf_conntrack_expect.h>
20 #include <linux/netfilter/nf_conntrack_amanda.h>
22 MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
23 MODULE_DESCRIPTION("Amanda NAT helper");
24 MODULE_LICENSE("GPL");
25 MODULE_ALIAS("ip_nat_amanda");
27 static unsigned int help(struct sk_buff
**pskb
,
28 enum ip_conntrack_info ctinfo
,
29 unsigned int matchoff
,
30 unsigned int matchlen
,
31 struct nf_conntrack_expect
*exp
)
33 char buffer
[sizeof("65535")];
37 /* Connection comes from client. */
38 exp
->saved_proto
.tcp
.port
= exp
->tuple
.dst
.u
.tcp
.port
;
39 exp
->dir
= IP_CT_DIR_ORIGINAL
;
41 /* When you see the packet, we need to NAT it the same as the
42 * this one (ie. same IP: it will be TCP and master is UDP). */
43 exp
->expectfn
= nf_nat_follow_master
;
45 /* Try to get same port: if not, try to change it. */
46 for (port
= ntohs(exp
->saved_proto
.tcp
.port
); port
!= 0; port
++) {
47 exp
->tuple
.dst
.u
.tcp
.port
= htons(port
);
48 if (nf_conntrack_expect_related(exp
) == 0)
55 sprintf(buffer
, "%u", port
);
56 ret
= nf_nat_mangle_udp_packet(pskb
, exp
->master
, ctinfo
,
58 buffer
, strlen(buffer
));
60 nf_conntrack_unexpect_related(exp
);
64 static void __exit
nf_nat_amanda_fini(void)
66 rcu_assign_pointer(nf_nat_amanda_hook
, NULL
);
70 static int __init
nf_nat_amanda_init(void)
72 BUG_ON(rcu_dereference(nf_nat_amanda_hook
));
73 rcu_assign_pointer(nf_nat_amanda_hook
, help
);
77 module_init(nf_nat_amanda_init
);
78 module_exit(nf_nat_amanda_fini
);