1 /* 2 * NetBIOS name service broadcast connection tracking helper 3 * 4 * (c) 2005 Patrick McHardy <kaber@trash.net> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 /* 12 * This helper tracks locally originating NetBIOS name service 13 * requests by issuing permanent expectations (valid until 14 * timing out) matching all reply connections from the 15 * destination network. The only NetBIOS specific thing is 16 * actually the port number. 17 */ 18 #include <linux/kernel.h> 19 #include <linux/module.h> 20 #include <linux/init.h> 21 #include <linux/in.h> 22 23 #include <net/netfilter/nf_conntrack.h> 24 #include <net/netfilter/nf_conntrack_helper.h> 25 #include <net/netfilter/nf_conntrack_expect.h> 26 27 #define NMBD_PORT 137 28 29 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); 30 MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper"); 31 MODULE_LICENSE("GPL"); 32 MODULE_ALIAS("ip_conntrack_netbios_ns"); 33 MODULE_ALIAS_NFCT_HELPER("netbios_ns"); 34 35 static unsigned int timeout __read_mostly = 3; 36 module_param(timeout, uint, 0400); 37 MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds"); 38 39 static struct nf_conntrack_expect_policy exp_policy = { 40 .max_expected = 1, 41 }; 42 43 static int netbios_ns_help(struct sk_buff *skb, unsigned int protoff, 44 struct nf_conn *ct, 45 enum ip_conntrack_info ctinfo) 46 { 47 return nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout); 48 } 49 50 static struct nf_conntrack_helper helper __read_mostly = { 51 .name = "netbios-ns", 52 .tuple.src.l3num = NFPROTO_IPV4, 53 .tuple.src.u.udp.port = cpu_to_be16(NMBD_PORT), 54 .tuple.dst.protonum = IPPROTO_UDP, 55 .me = THIS_MODULE, 56 .help = netbios_ns_help, 57 .expect_policy = &exp_policy, 58 }; 59 60 static int __init nf_conntrack_netbios_ns_init(void) 61 { 62 NF_CT_HELPER_BUILD_BUG_ON(0); 63 64 exp_policy.timeout = timeout; 65 return nf_conntrack_helper_register(&helper); 66 } 67 68 static void __exit nf_conntrack_netbios_ns_fini(void) 69 { 70 nf_conntrack_helper_unregister(&helper); 71 } 72 73 module_init(nf_conntrack_netbios_ns_init); 74 module_exit(nf_conntrack_netbios_ns_fini); 75