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
, struct xt_action_param
*par
)
30 const struct ipt_ttl_info
*info
= par
->matchinfo
;
31 const u8 ttl
= ip_hdr(skb
)->ttl
;
35 return ttl
== info
->ttl
;
37 return ttl
!= info
->ttl
;
39 return ttl
< info
->ttl
;
41 return ttl
> info
->ttl
;
47 static bool hl_mt6(const struct sk_buff
*skb
, struct xt_action_param
*par
)
49 const struct ip6t_hl_info
*info
= par
->matchinfo
;
50 const struct ipv6hdr
*ip6h
= ipv6_hdr(skb
);
54 return ip6h
->hop_limit
== info
->hop_limit
;
56 return ip6h
->hop_limit
!= info
->hop_limit
;
58 return ip6h
->hop_limit
< info
->hop_limit
;
60 return ip6h
->hop_limit
> info
->hop_limit
;
66 static struct xt_match hl_mt_reg
[] __read_mostly
= {
70 .family
= NFPROTO_IPV4
,
72 .matchsize
= sizeof(struct ipt_ttl_info
),
78 .family
= NFPROTO_IPV6
,
80 .matchsize
= sizeof(struct ip6t_hl_info
),
85 static int __init
hl_mt_init(void)
87 return xt_register_matches(hl_mt_reg
, ARRAY_SIZE(hl_mt_reg
));
90 static void __exit
hl_mt_exit(void)
92 xt_unregister_matches(hl_mt_reg
, ARRAY_SIZE(hl_mt_reg
));
95 module_init(hl_mt_init
);
96 module_exit(hl_mt_exit
);
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