Root/target/linux/generic-2.4/patches/605-netfilter_TTL.patch

1--- a/Documentation/Configure.help
2+++ b/Documentation/Configure.help
3@@ -3220,6 +3220,15 @@ CONFIG_IP_NF_TARGET_CLASSIFY
4   If you want to compile it as a module, say M here and read
5   Documentation/modules.txt. If unsure, say `N'.
6 
7+TTL target support
8+CONFIG_IP_NF_TARGET_TTL
9+ This option adds a `TTL' target, which enables the user to set
10+ the TTL value or increment / decrement the TTL value by a given
11+ amount.
12+
13+ If you want to compile it as a module, say M here and read
14+ Documentation/modules.txt. If unsure, say `N'.
15+
16 ipchains (2.2-style) support
17 CONFIG_IP_NF_COMPAT_IPCHAINS
18   This option places ipchains (with masquerading and redirection
19--- /dev/null
20+++ b/include/linux/netfilter_ipv4/ipt_TTL.h
21@@ -0,0 +1,21 @@
22+/* TTL modification module for IP tables
23+ * (C) 2000 by Harald Welte <laforge@gnumonks.org> */
24+
25+#ifndef _IPT_TTL_H
26+#define _IPT_TTL_H
27+
28+enum {
29+ IPT_TTL_SET = 0,
30+ IPT_TTL_INC,
31+ IPT_TTL_DEC
32+};
33+
34+#define IPT_TTL_MAXMODE IPT_TTL_DEC
35+
36+struct ipt_TTL_info {
37+ u_int8_t mode;
38+ u_int8_t ttl;
39+};
40+
41+
42+#endif
43--- a/net/ipv4/netfilter/Config.in
44+++ b/net/ipv4/netfilter/Config.in
45@@ -110,6 +110,7 @@ if [ "$CONFIG_IP_NF_IPTABLES" != "n" ];
46     dep_tristate ' CLASSIFY target support (EXPERIMENTAL)' CONFIG_IP_NF_TARGET_CLASSIFY $CONFIG_IP_NF_MANGLE
47   fi
48   dep_tristate ' LOG target support' CONFIG_IP_NF_TARGET_LOG $CONFIG_IP_NF_IPTABLES
49+ dep_tristate ' TTL target support' CONFIG_IP_NF_TARGET_TTL $CONFIG_IP_NF_IPTABLES
50   dep_tristate ' ULOG target support' CONFIG_IP_NF_TARGET_ULOG $CONFIG_IP_NF_IPTABLES
51   dep_tristate ' TCPMSS target support' CONFIG_IP_NF_TARGET_TCPMSS $CONFIG_IP_NF_IPTABLES
52 fi
53--- /dev/null
54+++ b/net/ipv4/netfilter/ipt_TTL.c
55@@ -0,0 +1,110 @@
56+/* TTL modification target for IP tables
57+ * (C) 2000 by Harald Welte <laforge@gnumonks.org>
58+ *
59+ * Version: $Revision: 1.1 $
60+ *
61+ * This software is distributed under the terms of GNU GPL
62+ */
63+
64+#include <linux/module.h>
65+#include <linux/skbuff.h>
66+#include <linux/ip.h>
67+#include <net/checksum.h>
68+
69+#include <linux/netfilter_ipv4/ip_tables.h>
70+#include <linux/netfilter_ipv4/ipt_TTL.h>
71+
72+MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
73+MODULE_DESCRIPTION("IP tables TTL modification module");
74+MODULE_LICENSE("GPL");
75+
76+static unsigned int ipt_ttl_target(struct sk_buff **pskb, unsigned int hooknum,
77+ const struct net_device *in, const struct net_device *out,
78+ const void *targinfo, void *userinfo)
79+{
80+ struct iphdr *iph = (*pskb)->nh.iph;
81+ const struct ipt_TTL_info *info = targinfo;
82+ u_int16_t diffs[2];
83+ int new_ttl;
84+
85+ switch (info->mode) {
86+ case IPT_TTL_SET:
87+ new_ttl = info->ttl;
88+ break;
89+ case IPT_TTL_INC:
90+ new_ttl = iph->ttl + info->ttl;
91+ if (new_ttl > 255)
92+ new_ttl = 255;
93+ break;
94+ case IPT_TTL_DEC:
95+ new_ttl = iph->ttl - info->ttl;
96+ if (new_ttl < 0)
97+ new_ttl = 0;
98+ break;
99+ default:
100+ new_ttl = iph->ttl;
101+ break;
102+ }
103+
104+ if (new_ttl != iph->ttl) {
105+ diffs[0] = htons(((unsigned)iph->ttl) << 8) ^ 0xFFFF;
106+ iph->ttl = new_ttl;
107+ diffs[1] = htons(((unsigned)iph->ttl) << 8);
108+ iph->check = csum_fold(csum_partial((char *)diffs,
109+ sizeof(diffs),
110+ iph->check^0xFFFF));
111+ (*pskb)->nfcache |= NFC_ALTERED;
112+ }
113+
114+ return IPT_CONTINUE;
115+}
116+
117+static int ipt_ttl_checkentry(const char *tablename,
118+ const struct ipt_entry *e,
119+ void *targinfo,
120+ unsigned int targinfosize,
121+ unsigned int hook_mask)
122+{
123+ struct ipt_TTL_info *info = targinfo;
124+
125+ if (targinfosize != IPT_ALIGN(sizeof(struct ipt_TTL_info))) {
126+ printk(KERN_WARNING "TTL: targinfosize %u != %Zu\n",
127+ targinfosize,
128+ IPT_ALIGN(sizeof(struct ipt_TTL_info)));
129+ return 0;
130+ }
131+
132+ if (strcmp(tablename, "mangle")) {
133+ printk(KERN_WARNING "TTL: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
134+ return 0;
135+ }
136+
137+ if (info->mode > IPT_TTL_MAXMODE) {
138+ printk(KERN_WARNING "TTL: invalid or unknown Mode %u\n",
139+ info->mode);
140+ return 0;
141+ }
142+
143+ if ((info->mode != IPT_TTL_SET) && (info->ttl == 0)) {
144+ printk(KERN_WARNING "TTL: increment/decrement doesn't make sense with value 0\n");
145+ return 0;
146+ }
147+
148+ return 1;
149+}
150+
151+static struct ipt_target ipt_TTL = { { NULL, NULL }, "TTL",
152+ ipt_ttl_target, ipt_ttl_checkentry, NULL, THIS_MODULE };
153+
154+static int __init init(void)
155+{
156+ return ipt_register_target(&ipt_TTL);
157+}
158+
159+static void __exit fini(void)
160+{
161+ ipt_unregister_target(&ipt_TTL);
162+}
163+
164+module_init(init);
165+module_exit(fini);
166--- a/net/ipv4/netfilter/Makefile
167+++ b/net/ipv4/netfilter/Makefile
168@@ -101,6 +101,7 @@ obj-$(CONFIG_IP_NF_TARGET_MASQUERADE) +=
169 obj-$(CONFIG_IP_NF_TARGET_REDIRECT) += ipt_REDIRECT.o
170 obj-$(CONFIG_IP_NF_NAT_SNMP_BASIC) += ip_nat_snmp_basic.o
171 obj-$(CONFIG_IP_NF_TARGET_LOG) += ipt_LOG.o
172+obj-$(CONFIG_IP_NF_TARGET_TTL) += ipt_TTL.o
173 obj-$(CONFIG_IP_NF_TARGET_ULOG) += ipt_ULOG.o
174 obj-$(CONFIG_IP_NF_TARGET_TCPMSS) += ipt_TCPMSS.o
175 
176

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