1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
Index: iptables-1.4.0/extensions/libxt_TARPIT.c
===================================================================
--- /dev/null
+++ iptables-1.4.0/extensions/libxt_TARPIT.c
@@ -0,0 +1,55 @@
+/* Shared library add-on to iptables to add TARPIT target support */
+#include <stdio.h>
+#include <getopt.h>
+
+#include <xtables.h>
+#include <linux/netfilter/x_tables.h>
+
+static void TARPIT_help(void)
+{
+ fputs(
+"TARPIT takes no options\n"
+"\n", stdout);
+}
+
+static struct option TARPIT_opts[] = {
+ { 0 }
+};
+
+static int TARPIT_parse(int c, char **argv, int invert, unsigned int *flags,
+ const void *entry, struct xt_entry_target **target)
+{
+ return 0;
+}
+
+static void TARPIT_final_check(unsigned int flags)
+{
+}
+
+static void TARPIT_print(const void *ip, const struct xt_entry_target *target,
+ int numeric)
+{
+}
+
+static void TARPIT_save(const void *ip, const struct xt_entry_target *target)
+{
+}
+
+static struct xtables_target tarpit_target = {
+ .family = AF_INET,
+ .name = "TARPIT",
+ .version = IPTABLES_VERSION,
+ .size = XT_ALIGN(0),
+ .userspacesize = XT_ALIGN(0),
+ .help = TARPIT_help,
+ .parse = TARPIT_parse,
+ .final_check = TARPIT_final_check,
+ .print = TARPIT_print,
+ .save = TARPIT_save,
+ .extra_opts = TARPIT_opts
+};
+
+void _init(void)
+{
+ xtables_register_target(&tarpit_target);
+}
Index: iptables-1.4.0/extensions/libxt_TARPIT.man
===================================================================
--- /dev/null
+++ iptables-1.4.0/extensions/libxt_TARPIT.man
@@ -0,0 +1,34 @@
+Captures and holds incoming TCP connections using no local
+per-connection resources. Connections are accepted, but immediately
+switched to the persist state (0 byte window), in which the remote
+side stops sending data and asks to continue every 60-240 seconds.
+Attempts to close the connection are ignored, forcing the remote side
+to time out the connection in 12-24 minutes.
+
+This offers similar functionality to LaBrea
+<http://www.hackbusters.net/LaBrea/> but doesn't require dedicated
+hardware or IPs. Any TCP port that you would normally DROP or REJECT
+can instead become a tarpit.
+
+To tarpit connections to TCP port 80 destined for the current machine:
+.IP
+iptables -A INPUT -p tcp -m tcp --dport 80 -j TARPIT
+.P
+To significantly slow down Code Red/Nimda-style scans of unused address
+space, forward unused ip addresses to a Linux box not acting as a router
+(e.g. "ip route 10.0.0.0 255.0.0.0 ip.of.linux.box" on a Cisco), enable IP
+forwarding on the Linux box, and add:
+.IP
+iptables -A FORWARD -p tcp -j TARPIT
+.IP
+iptables -A FORWARD -j DROP
+.TP
+NOTE:
+If you use the conntrack module while you are using TARPIT, you should
+also use the NOTRACK target, or the kernel will unnecessarily allocate
+resources for each TARPITted connection. To TARPIT incoming
+connections to the standard IRC port while using conntrack, you could:
+.IP
+iptables -t raw -A PREROUTING -p tcp --dport 6667 -j NOTRACK
+.IP
+iptables -A INPUT -p tcp --dport 6667 -j TARPIT
Index: iptables-1.4.0/extensions/.TARPIT-testx
===================================================================
--- /dev/null
+++ iptables-1.4.0/extensions/.TARPIT-testx
@@ -0,0 +1,2 @@
+#! /bin/sh
+[ -f "$KERNEL_DIR/net/netfilter/xt_TARPIT.c" ] && echo "TARPIT"
|
