blob: 4c8f30a3d6d2762e69604c4b1f6cd6821663bc64 [file] [log] [blame]
* NetBIOS name service broadcast connection tracking helper
* (c) 2005 Patrick McHardy <>
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
* This helper tracks locally originating NetBIOS name service
* requests by issuing permanent expectations (valid until
* timing out) matching all reply connections from the
* destination network. The only NetBIOS specific thing is
* actually the port number.
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/in.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#define NMBD_PORT 137
MODULE_AUTHOR("Patrick McHardy <>");
MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
static unsigned int timeout __read_mostly = 3;
module_param(timeout, uint, S_IRUSR);
MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
static struct nf_conntrack_expect_policy exp_policy = {
.max_expected = 1,
static int netbios_ns_help(struct sk_buff *skb, unsigned int protoff,
struct nf_conn *ct, enum ip_conntrack_info ctinfo)
return nf_conntrack_broadcast_help(skb, protoff, ct, ctinfo, timeout);
static struct nf_conntrack_helper helper __read_mostly = {
.name = "netbios-ns",
.tuple.src.l3num = NFPROTO_IPV4,
.tuple.src.u.udp.port = cpu_to_be16(NMBD_PORT),
.tuple.dst.protonum = IPPROTO_UDP,
.help = netbios_ns_help,
.expect_policy = &exp_policy,
static int __init nf_conntrack_netbios_ns_init(void)
exp_policy.timeout = timeout;
return nf_conntrack_helper_register(&helper);
static void __exit nf_conntrack_netbios_ns_fini(void)