1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * NetBIOS name service broadcast connection tracking helper
5 * (c) 2005 Patrick McHardy <kaber@trash.net>
8 * This helper tracks locally originating NetBIOS name service
9 * requests by issuing permanent expectations (valid until
10 * timing out) matching all reply connections from the
11 * destination network. The only NetBIOS specific thing is
12 * actually the port number.
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
19 #include <net/netfilter/nf_conntrack.h>
20 #include <net/netfilter/nf_conntrack_helper.h>
21 #include <net/netfilter/nf_conntrack_expect.h>
23 #define HELPER_NAME "netbios-ns"
26 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
27 MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
28 MODULE_LICENSE("GPL");
29 MODULE_ALIAS("ip_conntrack_netbios_ns");
30 MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
32 static unsigned int timeout __read_mostly = 3;
33 module_param(timeout, uint, 0400);
34 MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
36 static struct nf_conntrack_expect_policy exp_policy = {
40 static int netbios_ns_help(struct sk_buff *skb, unsigned int protoff,
42 enum ip_conntrack_info ctinfo)
44 return nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout);
47 static struct nf_conntrack_helper helper __read_mostly = {
49 .tuple.src.l3num = NFPROTO_IPV4,
50 .tuple.src.u.udp.port = cpu_to_be16(NMBD_PORT),
51 .tuple.dst.protonum = IPPROTO_UDP,
53 .help = netbios_ns_help,
54 .expect_policy = &exp_policy,
57 static int __init nf_conntrack_netbios_ns_init(void)
59 NF_CT_HELPER_BUILD_BUG_ON(0);
61 exp_policy.timeout = timeout;
62 return nf_conntrack_helper_register(&helper);
65 static void __exit nf_conntrack_netbios_ns_fini(void)
67 nf_conntrack_helper_unregister(&helper);
70 module_init(nf_conntrack_netbios_ns_init);
71 module_exit(nf_conntrack_netbios_ns_fini);