tags 310580 + patch
thanks
hi,
attached an updated diff which should cleanly apply against
kernel-source-2.4.27. I didnt test compile nor its functionality.
bye,
- michael
diff -ruN kernel-source-2.4.27/Documentation/Configure.help
kernel-source-2.4.27-psd/Documentation/Configure.help
--- kernel-source-2.4.27/Documentation/Configure.help 2005-05-27
11:09:23.000000000 +0200
+++ kernel-source-2.4.27-psd/Documentation/Configure.help 2005-05-27
11:09:58.000000000 +0200
@@ -2976,6 +2976,14 @@
If you want to compile it as a module, say M here and read
<file:Documentation/modules.txt>. If unsure, say `N'.
+psd match support
+CONFIG_IP_NF_MATCH_PSD
+ This option adds a `psd' match, which allows you to create rules in
+ any iptables table wich will detect TCP and UDP port scans.
+
+ If you want to compile it as a module, say M here and read
+ Documentation/modules.txt. If unsure, say `N'.
+
conntrack match support
CONFIG_IP_NF_MATCH_CONNTRACK
This is a general conntrack match module, a superset of the state match.
diff -ruN kernel-source-2.4.27/include/linux/netfilter_ipv4/ipt_psd.h
kernel-source-2.4.27-psd/include/linux/netfilter_ipv4/ipt_psd.h
--- kernel-source-2.4.27/include/linux/netfilter_ipv4/ipt_psd.h 1970-01-01
01:00:00.000000000 +0100
+++ kernel-source-2.4.27-psd/include/linux/netfilter_ipv4/ipt_psd.h
2005-05-27 11:09:58.000000000 +0200
@@ -0,0 +1,40 @@
+#ifndef _IPT_PSD_H
+#define _IPT_PSD_H
+
+#include <linux/param.h>
+#include <linux/types.h>
+
+/*
+ * High port numbers have a lower weight to reduce the frequency of false
+ * positives, such as from passive mode FTP transfers.
+ */
+#define PORT_WEIGHT_PRIV 3
+#define PORT_WEIGHT_HIGH 1
+
+/*
+ * Port scan detection thresholds: at least COUNT ports need to be scanned
+ * from the same source, with no longer than DELAY ticks between ports.
+ */
+#define SCAN_MIN_COUNT 7
+#define SCAN_MAX_COUNT (SCAN_MIN_COUNT * PORT_WEIGHT_PRIV)
+#define SCAN_WEIGHT_THRESHOLD SCAN_MAX_COUNT
+#define SCAN_DELAY_THRESHOLD (300) /* old usage of HZ here was
erroneously and broke under uml */
+
+/*
+ * Keep track of up to LIST_SIZE source addresses, using a hash table of
+ * HASH_SIZE entries for faster lookups, but limiting hash collisions to
+ * HASH_MAX source addresses per the same hash value.
+ */
+#define LIST_SIZE 0x100
+#define HASH_LOG 9
+#define HASH_SIZE (1 << HASH_LOG)
+#define HASH_MAX 0x10
+
+struct ipt_psd_info {
+ unsigned int weight_threshold;
+ unsigned int delay_threshold;
+ unsigned short lo_ports_weight;
+ unsigned short hi_ports_weight;
+};
+
+#endif /*_IPT_PSD_H*/
diff -ruN kernel-source-2.4.27/net/ipv4/netfilter/Config.in
kernel-source-2.4.27-psd/net/ipv4/netfilter/Config.in
--- kernel-source-2.4.27/net/ipv4/netfilter/Config.in 2005-05-27
11:09:23.000000000 +0200
+++ kernel-source-2.4.27-psd/net/ipv4/netfilter/Config.in 2005-05-27
11:09:58.000000000 +0200
@@ -24,6 +24,7 @@
dep_tristate ' netfilter MARK match support' CONFIG_IP_NF_MATCH_MARK
$CONFIG_IP_NF_IPTABLES
dep_tristate ' Multiple port match support' CONFIG_IP_NF_MATCH_MULTIPORT
$CONFIG_IP_NF_IPTABLES
dep_tristate ' TOS match support' CONFIG_IP_NF_MATCH_TOS
$CONFIG_IP_NF_IPTABLES
+ dep_tristate ' psd match support' CONFIG_IP_NF_MATCH_PSD
$CONFIG_IP_NF_IPTABLES
dep_tristate ' recent match support' CONFIG_IP_NF_MATCH_RECENT
$CONFIG_IP_NF_IPTABLES
dep_tristate ' ECN match support' CONFIG_IP_NF_MATCH_ECN
$CONFIG_IP_NF_IPTABLES
diff -ruN kernel-source-2.4.27/net/ipv4/netfilter/Makefile
kernel-source-2.4.27-psd/net/ipv4/netfilter/Makefile
--- kernel-source-2.4.27/net/ipv4/netfilter/Makefile 2005-05-27
11:09:23.000000000 +0200
+++ kernel-source-2.4.27-psd/net/ipv4/netfilter/Makefile 2005-05-27
11:09:58.000000000 +0200
@@ -73,6 +73,8 @@
obj-$(CONFIG_IP_NF_MATCH_OWNER) += ipt_owner.o
obj-$(CONFIG_IP_NF_MATCH_TOS) += ipt_tos.o
+obj-$(CONFIG_IP_NF_MATCH_PSD) += ipt_psd.o
+
obj-$(CONFIG_IP_NF_MATCH_RECENT) += ipt_recent.o
obj-$(CONFIG_IP_NF_MATCH_ECN) += ipt_ecn.o
diff -ruN kernel-source-2.4.27/net/ipv4/netfilter/ipt_psd.c
kernel-source-2.4.27-psd/net/ipv4/netfilter/ipt_psd.c
--- kernel-source-2.4.27/net/ipv4/netfilter/ipt_psd.c 1970-01-01
01:00:00.000000000 +0100
+++ kernel-source-2.4.27-psd/net/ipv4/netfilter/ipt_psd.c 2005-05-27
11:09:58.000000000 +0200
@@ -0,0 +1,361 @@
+/*
+ This is a module which is used for PSD (portscan detection)
+ Derived from scanlogd v2.1 written by Solar Designer <[EMAIL PROTECTED]>
+ and LOG target module.
+
+ Copyright (C) 2000,2001 astaro AG
+
+ This file is distributed under the terms of the GNU General Public
+ License (GPL). Copies of the GPL can be obtained from:
+ ftp://prep.ai.mit.edu/pub/gnu/GPL
+
+ 2000-05-04 Markus Hennig <[EMAIL PROTECTED]> : initial
+ 2000-08-18 Dennis Koslowski <[EMAIL PROTECTED]> : first release
+ 2000-12-01 Dennis Koslowski <[EMAIL PROTECTED]> : UDP scans detection added
+ 2001-01-02 Dennis Koslowski <[EMAIL PROTECTED]> : output modified
+ 2001-02-04 Jan Rekorajski <[EMAIL PROTECTED]> : converted from target to
match
+*/
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <net/tcp.h>
+#include <linux/spinlock.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_psd.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dennis Koslowski <[EMAIL PROTECTED]>");
+
+#define HF_DADDR_CHANGING 0x01
+#define HF_SPORT_CHANGING 0x02
+#define HF_TOS_CHANGING 0x04
+#define HF_TTL_CHANGING 0x08
+
+/*
+ * Information we keep per each target port
+ */
+struct port {
+ u_int16_t number; /* port number */
+ u_int8_t proto; /* protocol number */
+ u_int8_t and_flags; /* tcp ANDed flags */
+ u_int8_t or_flags; /* tcp ORed flags */
+};
+
+/*
+ * Information we keep per each source address.
+ */
+struct host {
+ struct host *next; /* Next entry with the same hash */
+ clock_t timestamp; /* Last update time */
+ struct in_addr src_addr; /* Source address */
+ struct in_addr dest_addr; /* Destination address */
+ unsigned short src_port; /* Source port */
+ int count; /* Number of ports in the list */
+ int weight; /* Total weight of ports in the list */
+ struct port ports[SCAN_MAX_COUNT - 1]; /* List of ports */
+ unsigned char tos; /* TOS */
+ unsigned char ttl; /* TTL */
+ unsigned char flags; /* HF_ flags bitmask */
+};
+
+/*
+ * State information.
+ */
+static struct {
+ spinlock_t lock;
+ struct host list[LIST_SIZE]; /* List of source addresses */
+ struct host *hash[HASH_SIZE]; /* Hash: pointers into the list */
+ int index; /* Oldest entry to be replaced */
+} state;
+
+/*
+ * Convert an IP address into a hash table index.
+ */
+static inline int hashfunc(struct in_addr addr)
+{
+ unsigned int value;
+ int hash;
+
+ value = addr.s_addr;
+ hash = 0;
+ do {
+ hash ^= value;
+ } while ((value >>= HASH_LOG));
+
+ return hash & (HASH_SIZE - 1);
+}
+
+static int
+ipt_psd_match(const struct sk_buff *pskb,
+ const struct net_device *in,
+ const struct net_device *out,
+ const void *matchinfo,
+ int offset,
+ const void *hdr,
+ u_int16_t datalen,
+ int *hotdrop)
+{
+ struct iphdr *ip_hdr;
+ struct tcphdr *tcp_hdr;
+ struct in_addr addr;
+ u_int16_t src_port,dest_port;
+ u_int8_t tcp_flags, proto;
+ clock_t now;
+ struct host *curr, *last, **head;
+ int hash, index, count;
+
+ /* Parameters from userspace */
+ const struct ipt_psd_info *psdinfo = matchinfo;
+
+ /* IP header */
+ ip_hdr = pskb->nh.iph;
+
+ /* Sanity check */
+ if (ntohs(ip_hdr->frag_off) & IP_OFFSET) {
+ DEBUGP("PSD: sanity check failed\n");
+ return 0;
+ }
+
+ /* TCP or UDP ? */
+ proto = ip_hdr->protocol;
+
+ if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) {
+ DEBUGP("PSD: protocol not supported\n");
+ return 0;
+ }
+
+ /* Get the source address, source & destination ports, and TCP flags */
+
+ addr.s_addr = ip_hdr->saddr;
+
+ tcp_hdr = (struct tcphdr*)((u_int32_t *)ip_hdr + ip_hdr->ihl);
+
+ /* Yep, itīs dirty */
+ src_port = tcp_hdr->source;
+ dest_port = tcp_hdr->dest;
+
+ if (proto == IPPROTO_TCP) {
+ tcp_flags = *((u_int8_t*)tcp_hdr + 13);
+ }
+ else {
+ tcp_flags = 0x00;
+ }
+
+ /* We're using IP address 0.0.0.0 for a special purpose here, so don't
let
+ * them spoof us. [DHCP needs this feature - HW] */
+ if (!addr.s_addr) {
+ DEBUGP("PSD: spoofed source address (0.0.0.0)\n");
+ return 0;
+ }
+
+ /* Use jiffies here not to depend on someone setting the time while
we're
+ * running; we need to be careful with possible return value overflows.
*/
+ now = jiffies;
+
+ spin_lock(&state.lock);
+
+ /* Do we know this source address already? */
+ count = 0;
+ last = NULL;
+ if ((curr = *(head = &state.hash[hash = hashfunc(addr)])))
+ do {
+ if (curr->src_addr.s_addr == addr.s_addr) break;
+ count++;
+ if (curr->next) last = curr;
+ } while ((curr = curr->next));
+
+ if (curr) {
+
+ /* We know this address, and the entry isn't too old. Update
it. */
+ if (now - curr->timestamp <= (psdinfo->delay_threshold*HZ)/100
&&
+ time_after_eq(now, curr->timestamp)) {
+
+ /* Just update the appropriate list entry if we've seen
this port already */
+ for (index = 0; index < curr->count; index++) {
+ if (curr->ports[index].number == dest_port) {
+ curr->ports[index].proto = proto;
+ curr->ports[index].and_flags &=
tcp_flags;
+ curr->ports[index].or_flags |=
tcp_flags;
+ goto out_no_match;
+ }
+ }
+
+ /* TCP/ACK and/or TCP/RST to a new port? This could be
an outgoing connection. */
+ if (proto == IPPROTO_TCP && (tcp_hdr->ack ||
tcp_hdr->rst))
+ goto out_no_match;
+
+ /* Packet to a new port, and not TCP/ACK: update the
timestamp */
+ curr->timestamp = now;
+
+ /* Logged this scan already? Then drop the packet. */
+ if (curr->weight >= psdinfo->weight_threshold)
+ goto out_match;
+
+ /* Specify if destination address, source port, TOS or
TTL are not fixed */
+ if (curr->dest_addr.s_addr != ip_hdr->daddr)
+ curr->flags |= HF_DADDR_CHANGING;
+ if (curr->src_port != src_port)
+ curr->flags |= HF_SPORT_CHANGING;
+ if (curr->tos != ip_hdr->tos)
+ curr->flags |= HF_TOS_CHANGING;
+ if (curr->ttl != ip_hdr->ttl)
+ curr->flags |= HF_TTL_CHANGING;
+
+ /* Update the total weight */
+ curr->weight += (ntohs(dest_port) < 1024) ?
+ psdinfo->lo_ports_weight :
psdinfo->hi_ports_weight;
+
+ /* Got enough destination ports to decide that this is
a scan? */
+ /* Then log it and drop the packet. */
+ if (curr->weight >= psdinfo->weight_threshold)
+ goto out_match;
+
+ /* Remember the new port */
+ if (curr->count < SCAN_MAX_COUNT) {
+ curr->ports[curr->count].number = dest_port;
+ curr->ports[curr->count].proto = proto;
+ curr->ports[curr->count].and_flags = tcp_flags;
+ curr->ports[curr->count].or_flags = tcp_flags;
+ curr->count++;
+ }
+
+ goto out_no_match;
+ }
+
+ /* We know this address, but the entry is outdated. Mark it
unused, and
+ * remove from the hash table. We'll allocate a new entry
instead since
+ * this one might get re-used too soon. */
+ curr->src_addr.s_addr = 0;
+ if (last)
+ last->next = last->next->next;
+ else if (*head)
+ *head = (*head)->next;
+ last = NULL;
+ }
+
+ /* We don't need an ACK from a new source address */
+ if (proto == IPPROTO_TCP && tcp_hdr->ack)
+ goto out_no_match;
+
+ /* Got too many source addresses with the same hash value? Then remove
the
+ * oldest one from the hash table, so that they can't take too much of
our
+ * CPU time even with carefully chosen spoofed IP addresses. */
+ if (count >= HASH_MAX && last) last->next = NULL;
+
+ /* We're going to re-use the oldest list entry, so remove it from the
hash
+ * table first (if it is really already in use, and isn't removed from
the
+ * hash table already because of the HASH_MAX check above). */
+
+ /* First, find it */
+ if (state.list[state.index].src_addr.s_addr)
+ head = &state.hash[hashfunc(state.list[state.index].src_addr)];
+ else
+ head = &last;
+ last = NULL;
+ if ((curr = *head))
+ do {
+ if (curr == &state.list[state.index]) break;
+ last = curr;
+ } while ((curr = curr->next));
+
+ /* Then, remove it */
+ if (curr) {
+ if (last)
+ last->next = last->next->next;
+ else if (*head)
+ *head = (*head)->next;
+ }
+
+ /* Get our list entry */
+ curr = &state.list[state.index++];
+ if (state.index >= LIST_SIZE) state.index = 0;
+
+ /* Link it into the hash table */
+ head = &state.hash[hash];
+ curr->next = *head;
+ *head = curr;
+
+ /* And fill in the fields */
+ curr->timestamp = now;
+ curr->src_addr = addr;
+ curr->dest_addr.s_addr = ip_hdr->daddr;
+ curr->src_port = src_port;
+ curr->count = 1;
+ curr->weight = (ntohs(dest_port) < 1024) ?
+ psdinfo->lo_ports_weight : psdinfo->hi_ports_weight;
+ curr->ports[0].number = dest_port;
+ curr->ports[0].proto = proto;
+ curr->ports[0].and_flags = tcp_flags;
+ curr->ports[0].or_flags = tcp_flags;
+ curr->tos = ip_hdr->tos;
+ curr->ttl = ip_hdr->ttl;
+
+out_no_match:
+ spin_unlock(&state.lock);
+ return 0;
+
+out_match:
+ spin_unlock(&state.lock);
+ return 1;
+}
+
+static int ipt_psd_checkentry(const char *tablename,
+ const struct ipt_ip *e,
+ void *matchinfo,
+ unsigned int matchsize,
+ unsigned int hook_mask)
+{
+/* const struct ipt_psd_info *psdinfo = targinfo;*/
+
+ /* we accept TCP only */
+/* if (e->ip.proto != IPPROTO_TCP) { */
+/* DEBUGP("PSD: specified protocol may be TCP only\n"); */
+/* return 0; */
+/* } */
+
+ if (matchsize != IPT_ALIGN(sizeof(struct ipt_psd_info))) {
+ DEBUGP("PSD: matchsize %u != %u\n",
+ matchsize,
+ IPT_ALIGN(sizeof(struct ipt_psd_info)));
+ return 0;
+ }
+
+ return 1;
+}
+
+static struct ipt_match ipt_psd_reg = {
+ {NULL, NULL},
+ "psd",
+ ipt_psd_match,
+ ipt_psd_checkentry,
+ NULL,
+ THIS_MODULE };
+
+static int __init init(void)
+{
+ if (ipt_register_match(&ipt_psd_reg))
+ return -EINVAL;
+
+ memset(&state, 0, sizeof(state));
+
+ spin_lock_init(&(state.lock));
+
+ printk("netfilter PSD loaded - (c) astaro AG\n");
+ return 0;
+}
+
+static void __exit fini(void)
+{
+ ipt_unregister_match(&ipt_psd_reg);
+ printk("netfilter PSD unloaded - (c) astaro AG\n");
+}
+
+module_init(init);
+module_exit(fini);
