2 * IP tables module for matching the value of the TTL
3 * (C) 2000,2001 by Harald Welte <laforge@netfilter.org>
5 * Hop Limit matching module
6 * (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
14 #include <linux/ipv6.h>
15 #include <linux/module.h>
16 #include <linux/skbuff.h>
18 #include <linux/netfilter/x_tables.h>
19 #include <linux/netfilter_ipv4/ipt_ttl.h>
20 #include <linux/netfilter_ipv6/ip6t_hl.h>
22 MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
23 MODULE_DESCRIPTION("Xtables: Hoplimit/TTL field match");
24 MODULE_LICENSE("GPL");
25 MODULE_ALIAS("ipt_ttl");
26 MODULE_ALIAS("ip6t_hl");
28 static bool ttl_mt(const struct sk_buff *skb,
29 const struct xt_action_param *par)
31 const struct ipt_ttl_info *info = par->matchinfo;
32 const u8 ttl = ip_hdr(skb)->ttl;
36 return ttl == info->ttl;
38 return ttl != info->ttl;
40 return ttl < info->ttl;
42 return ttl > info->ttl;
48 static bool hl_mt6(const struct sk_buff *skb,
49 const struct xt_action_param *par)
51 const struct ip6t_hl_info *info = par->matchinfo;
52 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
56 return ip6h->hop_limit == info->hop_limit;
58 return ip6h->hop_limit != info->hop_limit;
60 return ip6h->hop_limit < info->hop_limit;
62 return ip6h->hop_limit > info->hop_limit;
68 static struct xt_match hl_mt_reg[] __read_mostly = {
72 .family = NFPROTO_IPV4,
74 .matchsize = sizeof(struct ipt_ttl_info),
80 .family = NFPROTO_IPV6,
82 .matchsize = sizeof(struct ip6t_hl_info),
87 static int __init hl_mt_init(void)
89 return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
92 static void __exit hl_mt_exit(void)
94 xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
97 module_init(hl_mt_init);
98 module_exit(hl_mt_exit);