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net/netfilter/nf_conntrack_snmp.c
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/* * SNMP service broadcast connection tracking helper * * (c) 2011 Jiri Olsa <jolsa@redhat.com> * * 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. */ #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> #include <linux/netfilter/nf_conntrack_snmp.h> #define SNMP_PORT 161 MODULE_AUTHOR("Jiri Olsa <jolsa@redhat.com>"); MODULE_DESCRIPTION("SNMP service broadcast connection tracking helper"); MODULE_LICENSE("GPL"); MODULE_ALIAS_NFCT_HELPER("snmp"); static unsigned int timeout __read_mostly = 30; module_param(timeout, uint, S_IRUSR); MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds"); int (*nf_nat_snmp_hook)(struct sk_buff *skb, unsigned int protoff, struct nf_conn *ct, enum ip_conntrack_info ctinfo); EXPORT_SYMBOL_GPL(nf_nat_snmp_hook); static int snmp_conntrack_help(struct sk_buff *skb, unsigned int protoff, struct nf_conn *ct, enum ip_conntrack_info ctinfo) { typeof(nf_nat_snmp_hook) nf_nat_snmp; nf_conntrack_broadcast_help(skb, protoff, ct, ctinfo, timeout); nf_nat_snmp = rcu_dereference(nf_nat_snmp_hook); if (nf_nat_snmp && ct->status & IPS_NAT_MASK) return nf_nat_snmp(skb, protoff, ct, ctinfo); return NF_ACCEPT; } static struct nf_conntrack_expect_policy exp_policy = { .max_expected = 1, }; static struct nf_conntrack_helper helper __read_mostly = { .name = "snmp", .tuple.src.l3num = NFPROTO_IPV4, .tuple.src.u.udp.port = cpu_to_be16(SNMP_PORT), .tuple.dst.protonum = IPPROTO_UDP, .me = THIS_MODULE, .help = snmp_conntrack_help, .expect_policy = &exp_policy, }; static int __init nf_conntrack_snmp_init(void) { exp_policy.timeout = timeout; return nf_conntrack_helper_register(&helper); } static void __exit nf_conntrack_snmp_fini(void) { nf_conntrack_helper_unregister(&helper); } module_init(nf_conntrack_snmp_init); module_exit(nf_conntrack_snmp_fini); |