1 /* IP tables module for matching the value of the TTL
3 * ipt_ttl.c,v 1.5 2000/11/13 11:16:08 laforge Exp
5 * (C) 2000,2001 by Harald Welte <laforge@netfilter.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #include <linux/module.h>
13 #include <linux/skbuff.h>
15 #include <linux/netfilter_ipv4/ipt_ttl.h>
16 #include <linux/netfilter_ipv4/ip_tables.h>
18 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
19 MODULE_DESCRIPTION("IP tables TTL matching module");
20 MODULE_LICENSE("GPL");
22 static int match(const struct sk_buff
*skb
, const struct net_device
*in
,
23 const struct net_device
*out
, const void *matchinfo
,
24 int offset
, int *hotdrop
)
26 const struct ipt_ttl_info
*info
= matchinfo
;
30 return (skb
->nh
.iph
->ttl
== info
->ttl
);
33 return (!(skb
->nh
.iph
->ttl
== info
->ttl
));
36 return (skb
->nh
.iph
->ttl
< info
->ttl
);
39 return (skb
->nh
.iph
->ttl
> info
->ttl
);
42 printk(KERN_WARNING
"ipt_ttl: unknown mode %d\n",
50 static int checkentry(const char *tablename
, const struct ipt_ip
*ip
,
51 void *matchinfo
, unsigned int matchsize
,
52 unsigned int hook_mask
)
54 if (matchsize
!= IPT_ALIGN(sizeof(struct ipt_ttl_info
)))
60 static struct ipt_match ttl_match
= {
63 .checkentry
= &checkentry
,
67 static int __init
init(void)
69 return ipt_register_match(&ttl_match
);
72 static void __exit
fini(void)
74 ipt_unregister_match(&ttl_match
);