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176 lines
4.8 KiB
Diff
176 lines
4.8 KiB
Diff
--- a/Documentation/Configure.help
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+++ b/Documentation/Configure.help
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@@ -3220,6 +3220,15 @@ CONFIG_IP_NF_TARGET_CLASSIFY
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If you want to compile it as a module, say M here and read
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Documentation/modules.txt. If unsure, say `N'.
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+TTL target support
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+CONFIG_IP_NF_TARGET_TTL
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+ This option adds a `TTL' target, which enables the user to set
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+ the TTL value or increment / decrement the TTL value by a given
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+ amount.
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+
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+ If you want to compile it as a module, say M here and read
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+ Documentation/modules.txt. If unsure, say `N'.
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+
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ipchains (2.2-style) support
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CONFIG_IP_NF_COMPAT_IPCHAINS
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This option places ipchains (with masquerading and redirection
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--- /dev/null
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+++ b/include/linux/netfilter_ipv4/ipt_TTL.h
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@@ -0,0 +1,21 @@
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+/* TTL modification module for IP tables
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+ * (C) 2000 by Harald Welte <laforge@gnumonks.org> */
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+
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+#ifndef _IPT_TTL_H
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+#define _IPT_TTL_H
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+
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+enum {
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+ IPT_TTL_SET = 0,
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+ IPT_TTL_INC,
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+ IPT_TTL_DEC
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+};
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+
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+#define IPT_TTL_MAXMODE IPT_TTL_DEC
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+
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+struct ipt_TTL_info {
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+ u_int8_t mode;
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+ u_int8_t ttl;
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+};
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+
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+
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+#endif
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--- a/net/ipv4/netfilter/Config.in
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+++ b/net/ipv4/netfilter/Config.in
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@@ -126,6 +126,7 @@ if [ "$CONFIG_IP_NF_IPTABLES" != "n" ];
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dep_tristate ' CLASSIFY target support (EXPERIMENTAL)' CONFIG_IP_NF_TARGET_CLASSIFY $CONFIG_IP_NF_MANGLE
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fi
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dep_tristate ' LOG target support' CONFIG_IP_NF_TARGET_LOG $CONFIG_IP_NF_IPTABLES
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+ dep_tristate ' TTL target support' CONFIG_IP_NF_TARGET_TTL $CONFIG_IP_NF_IPTABLES
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dep_tristate ' ULOG target support' CONFIG_IP_NF_TARGET_ULOG $CONFIG_IP_NF_IPTABLES
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dep_tristate ' TCPMSS target support' CONFIG_IP_NF_TARGET_TCPMSS $CONFIG_IP_NF_IPTABLES
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fi
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--- /dev/null
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+++ b/net/ipv4/netfilter/ipt_TTL.c
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@@ -0,0 +1,110 @@
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+/* TTL modification target for IP tables
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+ * (C) 2000 by Harald Welte <laforge@gnumonks.org>
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+ *
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+ * Version: $Revision: 1.1 $
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+ *
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+ * This software is distributed under the terms of GNU GPL
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+ */
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+
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+#include <linux/module.h>
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+#include <linux/skbuff.h>
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+#include <linux/ip.h>
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+#include <net/checksum.h>
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+
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+#include <linux/netfilter_ipv4/ip_tables.h>
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+#include <linux/netfilter_ipv4/ipt_TTL.h>
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+
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+MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
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+MODULE_DESCRIPTION("IP tables TTL modification module");
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+MODULE_LICENSE("GPL");
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+
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+static unsigned int ipt_ttl_target(struct sk_buff **pskb, unsigned int hooknum,
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+ const struct net_device *in, const struct net_device *out,
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+ const void *targinfo, void *userinfo)
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+{
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+ struct iphdr *iph = (*pskb)->nh.iph;
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+ const struct ipt_TTL_info *info = targinfo;
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+ u_int16_t diffs[2];
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+ int new_ttl;
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+
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+ switch (info->mode) {
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+ case IPT_TTL_SET:
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+ new_ttl = info->ttl;
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+ break;
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+ case IPT_TTL_INC:
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+ new_ttl = iph->ttl + info->ttl;
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+ if (new_ttl > 255)
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+ new_ttl = 255;
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+ break;
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+ case IPT_TTL_DEC:
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+ new_ttl = iph->ttl - info->ttl;
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+ if (new_ttl < 0)
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+ new_ttl = 0;
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+ break;
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+ default:
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+ new_ttl = iph->ttl;
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+ break;
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+ }
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+
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+ if (new_ttl != iph->ttl) {
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+ diffs[0] = htons(((unsigned)iph->ttl) << 8) ^ 0xFFFF;
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+ iph->ttl = new_ttl;
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+ diffs[1] = htons(((unsigned)iph->ttl) << 8);
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+ iph->check = csum_fold(csum_partial((char *)diffs,
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+ sizeof(diffs),
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+ iph->check^0xFFFF));
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+ (*pskb)->nfcache |= NFC_ALTERED;
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+ }
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+
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+ return IPT_CONTINUE;
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+}
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+
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+static int ipt_ttl_checkentry(const char *tablename,
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+ const struct ipt_entry *e,
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+ void *targinfo,
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+ unsigned int targinfosize,
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+ unsigned int hook_mask)
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+{
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+ struct ipt_TTL_info *info = targinfo;
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+
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+ if (targinfosize != IPT_ALIGN(sizeof(struct ipt_TTL_info))) {
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+ printk(KERN_WARNING "TTL: targinfosize %u != %Zu\n",
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+ targinfosize,
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+ IPT_ALIGN(sizeof(struct ipt_TTL_info)));
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+ return 0;
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+ }
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+
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+ if (strcmp(tablename, "mangle")) {
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+ printk(KERN_WARNING "TTL: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
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+ return 0;
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+ }
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+
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+ if (info->mode > IPT_TTL_MAXMODE) {
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+ printk(KERN_WARNING "TTL: invalid or unknown Mode %u\n",
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+ info->mode);
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+ return 0;
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+ }
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+
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+ if ((info->mode != IPT_TTL_SET) && (info->ttl == 0)) {
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+ printk(KERN_WARNING "TTL: increment/decrement doesn't make sense with value 0\n");
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+ return 0;
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+ }
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+
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+ return 1;
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+}
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+
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+static struct ipt_target ipt_TTL = { { NULL, NULL }, "TTL",
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+ ipt_ttl_target, ipt_ttl_checkentry, NULL, THIS_MODULE };
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+
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+static int __init init(void)
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+{
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+ return ipt_register_target(&ipt_TTL);
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+}
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+
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+static void __exit fini(void)
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+{
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+ ipt_unregister_target(&ipt_TTL);
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+}
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+
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+module_init(init);
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+module_exit(fini);
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--- a/net/ipv4/netfilter/Makefile
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+++ b/net/ipv4/netfilter/Makefile
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@@ -110,6 +110,7 @@ obj-$(CONFIG_IP_NF_TARGET_MASQUERADE) +=
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obj-$(CONFIG_IP_NF_TARGET_REDIRECT) += ipt_REDIRECT.o
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obj-$(CONFIG_IP_NF_NAT_SNMP_BASIC) += ip_nat_snmp_basic.o
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obj-$(CONFIG_IP_NF_TARGET_LOG) += ipt_LOG.o
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+obj-$(CONFIG_IP_NF_TARGET_TTL) += ipt_TTL.o
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obj-$(CONFIG_IP_NF_TARGET_ULOG) += ipt_ULOG.o
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obj-$(CONFIG_IP_NF_TARGET_TCPMSS) += ipt_TCPMSS.o
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