Snort v2.6.0 and Excessive Memory

["Ron Jenkins" <rjenkins () dibr net>]

I had to back off from v2.6.0, because it was not detect a high
percentage of alerts.

 

With 1GB of RAM and Snort v2.4.5 we still have 300MB free, but with
v2.6.0 there is only 70MB free.

 

Below is the config detection setting being used; config detection:
search-method ac-sparsebands

 

Does anyone have any ideas? Below is the configuration being used and
the load line.

 

Thanks...

 

 

/usr/local/bin/snort -i nic0 -e -d -D -c /etc/snort/snort.conf -l
/var/log/snort

 

 

 

#--------------------------------------------------

#   http://www.snort.org     Snort 2.6.0 config file

#     Contact: snort-sigs () lists sourceforge net

#--------------------------------------------------

# $Id$

#

###################################################

# This file contains a sample snort configuration. 

# You can take the following steps to create your own custom
configuration:

#

#  1) Set the variables for your network

#  2) Configure dynamic loaded libraries

#  3) Configure preprocessors

#  4) Configure output plugins

#  5) Add any runtime config directives

#  6) Customize your rule set

#

###################################################

# Step #1: Set the network variables:

#

# You must change the following variables to reflect your local network.
The

# variable is currently setup for an RFC 1918 address space.

#

# You can specify it explicitly as: 

#

# var HOME_NET 10.1.1.0/24

#

# or use global variable $<interfacename>_ADDRESS which will be always

# initialized to IP address and netmask of the network interface which
you run

# snort at.  Under Windows, this must be specified as

# $(<interfacename>_ADDRESS), such as:

# $(\Device\Packet_{12345678-90AB-CDEF-1234567890AB}_ADDRESS)

#

# var HOME_NET $eth0_ADDRESS

#

# You can specify lists of IP addresses for HOME_NET

# by separating the IPs with commas like this:

#

# var HOME_NET [10.1.1.0/24,192.168.1.0/24]

#

# MAKE SURE YOU DON'T PLACE ANY SPACES IN YOUR LIST!

#

# or you can specify the variable to be any IP address

# like this:

 

var HOME_NET any

 

# Set up the external network addresses as well.  A good start may be
"any"

var EXTERNAL_NET any

 

# Configure your server lists.  This allows snort to only look for
attacks to

# systems that have a service up.  Why look for HTTP attacks if you are
not

# running a web server?  This allows quick filtering based on IP
addresses

# These configurations MUST follow the same configuration scheme as
defined

# above for $HOME_NET.  

 

# List of DNS servers on your network 

var DNS_SERVERS $HOME_NET

 

# List of SMTP servers on your network

var SMTP_SERVERS $HOME_NET

 

# List of web servers on your network

var HTTP_SERVERS $HOME_NET

 

# List of sql servers on your network 

var SQL_SERVERS $HOME_NET

 

# List of telnet servers on your network

var TELNET_SERVERS $HOME_NET

 

# List of snmp servers on your network

var SNMP_SERVERS $HOME_NET

 

# Configure your service ports.  This allows snort to look for attacks
destined

# to a specific application only on the ports that application runs on.
For

# example, if you run a web server on port 8081, set your HTTP_PORTS
variable

# like this:

#

# var HTTP_PORTS 8081

#

# Port lists must either be continuous [eg 80:8080], or a single port
[eg 80].

# We will adding support for a real list of ports in the future.

 

# Ports you run web servers on

#

# Please note:  [80,8080] does not work.

# If you wish to define multiple HTTP ports,

# 

## var HTTP_PORTS 80 

## include somefile.rules 

## var HTTP_PORTS 8080

## include somefile.rules 

var HTTP_PORTS 80

 

# Ports you want to look for SHELLCODE on.

var SHELLCODE_PORTS !80

 

# Ports you do oracle attacks on

var ORACLE_PORTS 1521

 

# other variables

# 

# AIM servers.  AOL has a habit of adding new AIM servers, so instead of

# modifying the signatures when they do, we add them to this list of
servers.

var AIM_SERVERS
[64.12.24.0/23,64.12.28.0/23,64.12.161.0/24,64.12.163.0/24,64.12.200.0/2
4,205.188.3.0/24,205.188.5.0/24,205.188.7.0/24,205.188.9.0/24,205.188.15
3.0/24,205.188.179.0/24,205.188.248.0/24]

 

# Path to your rules files (this can be a relative path)

# Note for Windows users:  You are advised to make this an absolute
path,

# such as:  c:\snort\rules

var RULE_PATH /etc/snort

 

# Configure the snort decoder

# ============================

#

# Snort's decoder will alert on lots of things such as header

# truncation or options of unusual length or infrequently used tcp
options

#

#

# Stop generic decode events:

#

# config disable_decode_alerts

#

# Stop Alerts on experimental TCP options

#

# config disable_tcpopt_experimental_alerts

#

# Stop Alerts on obsolete TCP options

#

# config disable_tcpopt_obsolete_alerts

#

# Stop Alerts on T/TCP alerts

#

# In snort 2.0.1 and above, this only alerts when a TCP option is
detected

# that shows T/TCP being actively used on the network.  If this is
normal

# behavior for your network, disable the next option.

#

# config disable_tcpopt_ttcp_alerts

#

# Stop Alerts on all other TCPOption type events:

#

# config disable_tcpopt_alerts

#

# Stop Alerts on invalid ip options

#

# config disable_ipopt_alerts

 

# Configure the detection engine

# ===============================

#

# Use a different pattern matcher in case you have a machine with very
limited

# resources:

#

# config detection: search-method lowmem

config detection: search-method ac-sparsebands

 

# Configure Inline Resets

# ========================

# 

# If running an iptables firewall with snort in InlineMode() we can now

# perform resets via a physical device. We grab the indev from iptables

# and use this for the interface on which to send resets. This config

# option takes an argument for the src mac address you want to use in
the

# reset packet.  This way the bridge can remain stealthy. If the src mac

# option is not set we use the mac address of the indev device. If we

# don't set this option we will default to sending resets via raw
socket,

# which needs an ipaddress to be assigned to the int.

#

# config layer2resets: 00:06:76:DD:5F:E3

 

###################################################

# Step #2: Configure dynamic loaded libraries

#

# If snort was configured to use dynamically loaded libraries,

# those libraries can be loaded here.

#

# Each of the following configuration options can be done via

# the command line as well.

#

# Load all dynamic preprocessors from the install path

# (same as command line option --dynamic-preprocessor-lib-dir)

#

dynamicpreprocessor directory /usr/local/lib/snort_dynamicpreprocessor/

#

# Load a specific dynamic preprocessor library from the install path

# (same as command line option --dynamic-preprocessor-lib)

#

# dynamicpreprocessor file
/usr/local/lib/snort_dynamicpreprocessor/libdynamicexample.so

#

# Load a dynamic engine from the install path

# (same as command line option --dynamic-engine-lib)

#

dynamicengine /usr/local/lib/snort_dynamicengine/libsf_engine.so

#

# Load all dynamic rules libraries from the install path

# (same as command line option --dynamic-detection-lib-dir)

#

# dynamicdetection directory /usr/local/lib/snort_dynamicrule/

#

# Load a specific dynamic rule library from the install path

# (same as command line option --dynamic-detection-lib)

#

# dynamicdetection file
/usr/local/lib/snort_dynamicrule/libdynamicexamplerule.so

#

###################################################

# Step #3: Configure preprocessors

#

# General configuration for preprocessors is of 

# the form

# preprocessor <name_of_processor>: <configuration_options>

 

# Configure Flow tracking module

# -------------------------------

#

# The Flow tracking module is meant to start unifying the state keeping

# mechanisms of snort into a single place. Right now, only a portscan
detector

# is implemented but in the long term,  many of the stateful subsystems
of

# snort will be migrated over to becoming flow plugins. This must be
enabled

# for flow-portscan to work correctly.

#

# See README.flow for additional information

#

preprocessor flow: stats_interval 0 hash 2

 

# frag2: IP defragmentation support

# -------------------------------

# This preprocessor performs IP defragmentation.  This plugin will also
detect

# people launching fragmentation attacks (usually DoS) against hosts.
No

# arguments loads the default configuration of the preprocessor, which
is a 60

# second timeout and a 4MB fragment buffer. 

 

# The following (comma delimited) options are available for frag2

#    timeout [seconds] - sets the number of [seconds] that an unfinished


#                        fragment will be kept around waiting for
completion,

#                        if this time expires the fragment will be
flushed

#    memcap [bytes] - limit frag2 memory usage to [number] bytes

#                      (default:  4194304)

#

#    min_ttl [number] - minimum ttl to accept

# 

#    ttl_limit [number] - difference of ttl to accept without alerting

#                         will cause false positves with router flap

# 

# Frag2 uses Generator ID 113 and uses the following SIDS 

# for that GID:

#  SID     Event description

# -----   -------------------

#   1       Oversized fragment (reassembled frag > 64k bytes)

#   2       Teardrop-type attack

 

#preprocessor frag2

 

# frag3: Target-based IP defragmentation 

# --------------------------------------

#

# Frag3 is a brand new IP defragmentation preprocessor that is capable
of

# performing "target-based" processing of IP fragments.  Check out the

# README.frag3 file in the doc directory for more background and
configuration

# information.

# 

# Frag3 configuration is a two step process, a global initialization
phase 

# followed by the definition of a set of defragmentation engines.  

# 

# Global configuration defines the number of fragmented packets that
Snort can

# track at the same time and gives you options regarding the memory cap
for the

# subsystem or, optionally, allows you to preallocate all the memory for
the 

# entire frag3 system.

#

# frag3_global options:

#   max_frags: Maximum number of frag trackers that may be active at
once.  

#              Default value is 8192.

#   memcap: Maximum amount of memory that frag3 may access at any given
time.

#           Default value is 4MB.

#   prealloc_frags: Maximum number of individual fragments that may be
processed

#                   at once.  This is instead of the memcap system, uses
static 

#                   allocation to increase performance.  No default
value.  Each

#                   preallocated fragment eats ~1550 bytes.

#

# Target-based behavior is attached to an engine as a "policy" for
handling 

# overlaps and retransmissions as enumerated in the Paxson paper.  There
are

# currently five policy types available: "BSD", "BSD-right", "First",
"Linux" 

# and "Last".  Engines can be bound to bound to standard Snort CIDR
blocks or

# IP lists.

#

# frag3_engine options:

#   timeout: Amount of time a fragmented packet may be active before
expiring.

#            Default value is 60 seconds.

#   ttl_limit: Limit of delta allowable for TTLs of packets in the
fragments. 

#              Based on the initial received fragment TTL.

#   min_ttl: Minimum acceptable TTL for a fragment, frags with TTLs
below this

#            value will be discarded.  Default value is 0.

#   detect_anomalies: Activates frag3's anomaly detection mechanisms.

#   policy: Target-based policy to assign to this engine.  Default is
BSD.

#   bind_to: IP address set to bind this engine to.  Default is all
hosts.

#

# Frag3 configuration example:

#preprocessor frag3_global: max_frags 65536 prealloc_frags 262144

#preprocessor frag3_engine: policy linux \

#                           bind_to [10.1.1.12/32,10.1.1.13/32] \

#                           detect_anomalies

#preprocessor frag3_engine: policy first \

#                           bind_to 10.2.1.0/24 \

#                           detect_anomalies

#preprocessor frag3_engine: policy last \

#                           bind_to 10.3.1.0/24

#preprocessor frag3_engine: policy bsd

 

preprocessor frag3_global: max_frags 65536

preprocessor frag3_engine: policy first detect_anomalies

 

 

# stream4: stateful inspection/stream reassembly for Snort

#----------------------------------------------------------------------

# Use in concert with the -z [all|est] command line switch to defeat
stick/snot

# against TCP rules.  Also performs full TCP stream reassembly, stateful

# inspection of TCP streams, etc.  Can statefully detect various
portscan

# types, fingerprinting, ECN, etc.

 

# stateful inspection directive

# no arguments loads the defaults (timeout 30, memcap 8388608)

# options (options are comma delimited):

#   detect_scans - stream4 will detect stealth portscans and generate
alerts

#                  when it sees them when this option is set

#   detect_state_problems - detect TCP state problems, this tends to be
very

#                           noisy because there are a lot of crappy ip
stack

#                           implementations out there

#

#   disable_evasion_alerts - turn off the possibly noisy mitigation of

#                            overlapping sequences.

#

#

#   min_ttl [number]       - set a minium ttl that snort will accept to

#                            stream reassembly

#

#   ttl_limit [number]     - differential of the initial ttl on a
session versus

#                             the normal that someone may be playing
games.

#                             Routing flap may cause lots of false
positives.

# 

#   keepstats [machine|binary] - keep session statistics, add "machine"
to 

#                         get them in a flat format for machine reading,
add

#                         "binary" to get them in a unified binary
output 

#                         format

#   noinspect - turn off stateful inspection only

#   timeout [number] - set the session timeout counter to [number]
seconds,

#                      default is 30 seconds

#   max_sessions [number] - limit the number of sessions stream4 keeps

#                         track of

#   memcap [number] - limit stream4 memory usage to [number] bytes

#   log_flushed_streams - if an event is detected on a stream this
option will

#                         cause all packets that are stored in the
stream4

#                         packet buffers to be flushed to disk.  This
only 

#                         works when logging in pcap mode!

#   server_inspect_limit [bytes] - Byte limit on server side inspection.

#

# Stream4 uses Generator ID 111 and uses the following SIDS 

# for that GID:

#  SID     Event description

# -----   -------------------

#   1       Stealth activity

#   2       Evasive RST packet

#   3       Evasive TCP packet retransmission

#   4       TCP Window violation

#   5       Data on SYN packet

#   6       Stealth scan: full XMAS

#   7       Stealth scan: SYN-ACK-PSH-URG

#   8       Stealth scan: FIN scan

#   9       Stealth scan: NULL scan

#   10      Stealth scan: NMAP XMAS scan

#   11      Stealth scan: Vecna scan

#   12      Stealth scan: NMAP fingerprint scan stateful detect

#   13      Stealth scan: SYN-FIN scan

#   14      TCP forward overlap

 

preprocessor stream4: disable_evasion_alerts

 

# tcp stream reassembly directive

# no arguments loads the default configuration 

#   Only reassemble the client,

#   Only reassemble the default list of ports (See below),  

#   Give alerts for "bad" streams

#

# Available options (comma delimited):

#   clientonly - reassemble traffic for the client side of a connection
only

#   serveronly - reassemble traffic for the server side of a connection
only

#   both - reassemble both sides of a session

#   noalerts - turn off alerts from the stream reassembly stage of
stream4

#   ports [list] - use the space separated list of ports in [list],
"all" 

#                  will turn on reassembly for all ports, "default" will
turn

#                  on reassembly for ports 21, 23, 25, 42, 53, 80, 110,

#                  111, 135, 136, 137, 139, 143, 445, 513, 1433, 1521,

#                  and 3306

#   favor_old - favor an old segment (based on sequence number) over a
new one.

#               This is the default.

#   favor_new - favor an new segment (based on sequence number) over an
old one.

#   flush_behavior [mode] -

#           default      - use old static flushpoints (default)

#           large_window - use new larger static flushpoints

#           random       - use random flushpoints defined by flush_base,


#                          flush_seed and flush_range

#   flush_base [number] - lowest allowed random flushpoint (512 by
default)

#   flush_range [number] - number is the space within which random
flushpoints

#                          are generated (default 1213)

#   flush_seed [number] - seed for the random number generator, defaults
to 

#                         Snort PID + time

#

# Using the default random flushpoints, the smallest flushpoint is 512,

# and the largest is 1725 bytes.

preprocessor stream4_reassemble

 

# Performance Statistics

# ----------------------

# Documentation for this is provided in the Snort Manual.  You should
read it.

# It is included in the release distribution as doc/snort_manual.pdf

# 

# preprocessor perfmonitor: time 300 file /var/snort/snort.stats pktcnt
10000

 

# http_inspect: normalize and detect HTTP traffic and protocol anomalies

#

# lots of options available here. See doc/README.http_inspect.

# unicode.map should be wherever your snort.conf lives, or given

# a full path to where snort can find it.

preprocessor http_inspect: global \

    iis_unicode_map unicode.map 1252 

 

preprocessor http_inspect_server: server default \

    profile all ports { 80 8080 8180 } oversize_dir_length 500

 

#

#  Example unique server configuration

#

#preprocessor http_inspect_server: server 1.1.1.1 \

#    ports { 80 3128 8080 } \

#    flow_depth 0 \

#    ascii no \

#    double_decode yes \

#    non_rfc_char { 0x00 } \

#    chunk_length 500000 \

#    non_strict \

#    oversize_dir_length 300 \

#    no_alerts

 

 

# rpc_decode: normalize RPC traffic

# ---------------------------------

# RPC may be sent in alternate encodings besides the usual 4-byte
encoding

# that is used by default. This plugin takes the port numbers that RPC

# services are running on as arguments - it is assumed that the given
ports

# are actually running this type of service. If not, change the ports or
turn

# it off.

# The RPC decode preprocessor uses generator ID 106

#

# arguments: space separated list

# alert_fragments - alert on any rpc fragmented TCP data

# no_alert_multiple_requests - don't alert when >1 rpc query is in a
packet

# no_alert_large_fragments - don't alert when the fragmented

#                            sizes exceed the current packet size

# no_alert_incomplete - don't alert when a single segment

#                       exceeds the current packet size

 

preprocessor rpc_decode: 111 32771

 

# bo: Back Orifice detector

# -------------------------

# Detects Back Orifice traffic on the network.

#

# arguments:  

#   syntax:

#     preprocessor bo: noalert { client | server | general |
snort_attack } \

#                      drop    { client | server | general |
snort_attack }

#   example:

#     preprocessor bo: noalert { general server } drop { snort_attack }

 

# 

# The Back Orifice detector uses Generator ID 105 and uses the 

# following SIDS for that GID:

#  SID     Event description

# -----   -------------------

#   1       Back Orifice traffic detected

#   2       Back Orifice Client Traffic Detected

#   3       Back Orifice Server Traffic Detected

#   4       Back Orifice Snort Buffer Attack

 

preprocessor bo

 

# telnet_decode: Telnet negotiation string normalizer

# ---------------------------------------------------

# This preprocessor "normalizes" telnet negotiation strings from telnet
and ftp

# traffic.  It works in much the same way as the http_decode
preprocessor,

# searching for traffic that breaks up the normal data stream of a
protocol and

# replacing it with a normalized representation of that traffic so that
the

# "content" pattern matching keyword can work without requiring
modifications.

# This preprocessor requires no arguments.

#

# DEPRECATED in favor of ftp_telnet dynamic preprocessor

#preprocessor telnet_decode

#

# ftp_telnet: FTP & Telnet normalizer, protocol enforcement and buff
overflow

#
------------------------------------------------------------------------
---

# This preprocessor normalizes telnet negotiation strings from telnet
and

# ftp traffic.  It looks for traffic that breaks the normal data stream

# of the protocol, replacing it with a normalized representation of that

# traffic so that the "content" pattern matching keyword can work
without

# requiring modifications.

#

# It also performs protocol correctness checks for the FTP command
channel,

# and identifies open FTP data transfers.

#

# FTPTelnet has numerous options available, please read

# README.ftptelnet for help configuring the options for the global

# telnet, ftp server, and ftp client sections for the protocol.

 

#####

# Per Step #2, set the following to load the ftptelnet preprocessor

# dynamicpreprocessor <full path to libsf_ftptelnet_preproc.so>

# or use commandline option

# --dynamic-preprocessor-lib <full path to libsf_ftptelnet_preproc.so>

 

preprocessor ftp_telnet: global \

   encrypted_traffic yes \

   inspection_type stateful

 

preprocessor ftp_telnet_protocol: telnet \

   normalize \

   ayt_attack_thresh 200

 

# This is consistent with the FTP rules as of 18 Sept 2004.

# CWD can have param length of 200

# MODE has an additional mode of Z (compressed)

# Check for string formats in USER & PASS commands

# Check nDTM commands that set modification time on the file.

preprocessor ftp_telnet_protocol: ftp server default \

   def_max_param_len 100 \

   alt_max_param_len 200 { CWD } \

   cmd_validity MODE < char ASBCZ > \

   cmd_validity MDTM < [ date nnnnnnnnnnnnnn[.n[n[n]]] ] string > \

   chk_str_fmt { USER PASS RNFR RNTO SITE MKD } \

   telnet_cmds yes \

   data_chan

 

preprocessor ftp_telnet_protocol: ftp client default \

   max_resp_len 256 \

   bounce yes \

   telnet_cmds yes

 

# smtp: SMTP normalizer, protocol enforcement and buffer overflow

#
------------------------------------------------------------------------
---

# This preprocessor normalizes SMTP commands by removing extraneous
spaces.

# It looks for overly long command lines, response lines, and data
header lines.

# It can alert on invalid commands, or specific valid commands.  It can
optionally

# ignore mail data, and can ignore TLS encrypted data.

#

# It also performs protocol correctness checks for the FTP command
channel,

# and identifies open FTP data transfers.

#

# SMTP has numerous options available, please read README.smtp for help

# configuring options.

 

#####

# Per Step #2, set the following to load the smtp preprocessor

# dynamicpreprocessor <full path to libsf_smtp_preproc.so>

# or use commandline option

# --dynamic-preprocessor-lib <full path to libsf_smtp_preproc.so>

 

preprocessor smtp: \

  ports { 25 } \

  inspection_type stateful \

  normalize cmds \

  normalize_cmds { EXPN VRFY RCPT } \

  alt_max_command_line_len 260 { MAIL } \

  alt_max_command_line_len 300 { RCPT } \

  alt_max_command_line_len 500 { HELP HELO ETRN } \

  alt_max_command_line_len 255 { EXPN VRFY }

 

# sfPortscan

# ----------

# Portscan detection module.  Detects various types of portscans and

# portsweeps.  For more information on detection philosophy, alert
types,

# and detailed portscan information, please refer to the
README.sfportscan.

#

# -configuration options-

#     proto { tcp udp icmp ip all }

#       The arguments to the proto option are the types of protocol
scans that

#       the user wants to detect.  Arguments should be separated by
spaces and

#       not commas.

#     scan_type { portscan portsweep decoy_portscan distributed_portscan
all }

#       The arguments to the scan_type option are the scan types that
the

#       user wants to detect.  Arguments should be separated by spaces
and not

#       commas.

#     sense_level { low|medium|high }

#       There is only one argument to this option and it is the level of

#       sensitivity in which to detect portscans.  The 'low' sensitivity

#       detects scans by the common method of looking for response
errors, such

#       as TCP RSTs or ICMP unreachables.  This level requires the least

#       tuning.  The 'medium' sensitivity level detects portscans and 

#       filtered portscans (portscans that receive no response).  This

#       sensitivity level usually requires tuning out scan events from
NATed

#       IPs, DNS cache servers, etc.  The 'high' sensitivity level has

#       lower thresholds for portscan detection and a longer time window
than

#       the 'medium' sensitivity level.  Requires more tuning and may be
noisy

#       on very active networks.  However, this sensitivity levels
catches the

#       most scans.

#     memcap { positive integer }

#       The maximum number of bytes to allocate for portscan detection.
The

#       higher this number the more nodes that can be tracked.

#     logfile { filename }

#       This option specifies the file to log portscan and detailed
portscan

#       values to.  If there is not a leading /, then snort logs to the

#       configured log directory.  Refer to README.sfportscan for
details on

#       the logged values in the logfile.

#     watch_ip { Snort IP List }

#     ignore_scanners { Snort IP List }

#     ignore_scanned { Snort IP List }

#       These options take a snort IP list as the argument.  The
'watch_ip'

#       option specifies the IP(s) to watch for portscan.  The 

#       'ignore_scanners' option specifies the IP(s) to ignore as
scanners.

#       Note that these hosts are still watched as scanned hosts.  The

#       'ignore_scanners' option is used to tune alerts from very active

#       hosts such as NAT, nessus hosts, etc.  The 'ignore_scanned'
option 

#       specifies the IP(s) to ignore as scanned hosts.  Note that these
hosts

#       are still watched as scanner hosts.  The 'ignore_scanned' option
is

#       used to tune alerts from very active hosts such as syslog
servers, etc.

#     detect_ack_scans

#       This option will include sessions picked up in midstream by the
stream

#       module, which is necessary to detect ACK scans.  However, this
can lead to

#       false alerts, especially under heavy load with dropped packets;
which is why

#       the option is off by default.

#

preprocessor sfportscan: proto  { all } \

                         memcap { 10000000 } \

                         sense_level { low }

 

# arpspoof

#----------------------------------------

# Experimental ARP detection code from Jeff Nathan, detects ARP attacks,

# unicast ARP requests, and specific ARP mapping monitoring.  To make
use of

# this preprocessor you must specify the IP and hardware address of
hosts on

# the same layer 2 segment as you.  Specify one host IP MAC combo per
line.

# Also takes a "-unicast" option to turn on unicast ARP request
detection. 

# Arpspoof uses Generator ID 112 and uses the following SIDS for that
GID:

 

#  SID     Event description

# -----   -------------------

#   1       Unicast ARP request

#   2       Etherframe ARP mismatch (src)

#   3       Etherframe ARP mismatch (dst)

#   4       ARP cache overwrite attack

 

#preprocessor arpspoof

#preprocessor arpspoof_detect_host: 192.168.40.1 f0:0f:00:f0:0f:00

 

####################################################################

# Step #4: Configure output plugins

#

# Uncomment and configure the output plugins you decide to use.  General

# configuration for output plugins is of the form:

#

# output <name_of_plugin>: <configuration_options>

#

# alert_syslog: log alerts to syslog

# ----------------------------------

# Use one or more syslog facilities as arguments.  Win32 can also
optionally

# specify a particular hostname/port.  Under Win32, the default hostname
is

# '127.0.0.1', and the default port is 514.

#

# [Unix flavours should use this format...]

# output alert_syslog: LOG_AUTH LOG_ALERT

#

# [Win32 can use any of these formats...]

# output alert_syslog: LOG_AUTH LOG_ALERT

# output alert_syslog: host=hostname, LOG_AUTH LOG_ALERT

# output alert_syslog: host=hostname:port, LOG_AUTH LOG_ALERT

 

# log_tcpdump: log packets in binary tcpdump format

# -------------------------------------------------

# The only argument is the output file name.

#

# output log_tcpdump: tcpdump.log

 

# database: log to a variety of databases

# ---------------------------------------

# See the README.database file for more information about configuring

# and using this plugin.

#

output database: log, mysql, user=xxxxxxxx password=xxxxxxxx
dbname=xxxxxxxx host=localhost sensor_name=xxxxxxxxxxx

# output database: log, mysql, user=root password=test dbname=db
host=localhost

# output database: alert, postgresql, user=snort dbname=snort

# output database: log, odbc, user=snort dbname=snort

# output database: log, mssql, dbname=snort user=snort password=test

# output database: log, oracle, dbname=snort user=snort password=test

 

# unified: Snort unified binary format alerting and logging

# -------------------------------------------------------------

# The unified output plugin provides two new formats for logging and
generating

# alerts from Snort, the "unified" format.  The unified format is a
straight

# binary format for logging data out of Snort that is designed to be
fast and

# efficient.  Used with barnyard (the new alert/log processor), most of
the

# overhead for logging and alerting to various slow storage mechanisms
such as

# databases or the network can now be avoided.  

#

# Check out the spo_unified.h file for the data formats.

#

# Two arguments are supported.

#    filename - base filename to write to (current time_t is appended)

#    limit    - maximum size of spool file in MB (default: 128)

#

# output alert_unified: filename snort.alert, limit 128

# output log_unified: filename snort.log, limit 128

 

 

# prelude: log to the Prelude Hybrid IDS system

# ---------------------------------------------

#

# profile = Name of the Prelude profile to use (default is snort).

#

# Snort priority to IDMEF severity mappings:

# high < medium < low < info

#

# These are the default mapped from classification.config:

# info   = 4

# low    = 3

# medium = 2

# high   = anything below medium

#

# output alert_prelude

# output alert_prelude: profile=snort-profile-name

 

 

# You can optionally define new rule types and associate one or more
output

# plugins specifically to that type.

#

# This example will create a type that will log to just tcpdump.

# ruletype suspicious

# {

#   type log

#   output log_tcpdump: suspicious.log

# }

#

# EXAMPLE RULE FOR SUSPICIOUS RULETYPE:

# suspicious tcp $HOME_NET any -> $HOME_NET 6667 (msg:"Internal IRC
Server";)

#

# This example will create a rule type that will log to syslog and a
mysql

# database:

# ruletype redalert

# {

#   type alert

#   output alert_syslog: LOG_AUTH LOG_ALERT

#   output database: log, mysql, user=snort dbname=snort host=localhost

# }

#

# EXAMPLE RULE FOR REDALERT RULETYPE:

# redalert tcp $HOME_NET any -> $EXTERNAL_NET 31337 \

#   (msg:"Someone is being LEET"; flags:A+;)

 

#

# Include classification & priority settings

# Note for Windows users:  You are advised to make this an absolute
path,

# such as:  c:\snort\etc\classification.config

#

 

include classification.config

 

#

# Include reference systems

# Note for Windows users:  You are advised to make this an absolute
path,

# such as:  c:\snort\etc\reference.config

#

 

include reference.config

 

####################################################################

# Step #5: Configure snort with config statements

#

# See the snort manual for a full set of configuration references

#

# config flowbits_size: 64

#

# New global ignore_ports config option from Andy Mullican

#

# config ignore_ports: <tcp|udp> <list of ports separated by whitespace>

# config ignore_ports: tcp 21 6667:6671 1356

# config ignore_ports: udp 1:17 53

 

 

####################################################################

# Step #6: Customize your rule set

#

# Up to date snort rules are available at http://www.snort.org

#

# The snort web site has documentation about how to write your own
custom snort

# rules.

 

#=========================================

# Include all relevant rulesets here 

# 

# The following rulesets are disabled by default:

#

#   web-attacks, backdoor, shellcode, policy, porn, info, icmp-info,
virus,

#   chat, multimedia, and p2p

#            

# These rules are either site policy specific or require tuning in order
to not

# generate false positive alerts in most enviornments.

# 

# Please read the specific include file for more information and

# README.alert_order for how rule ordering affects how alerts are
triggered.

#=========================================

 

include $RULE_PATH/local.rules

include $RULE_PATH/bad-traffic.rules

include $RULE_PATH/exploit.rules

include $RULE_PATH/scan.rules

include $RULE_PATH/finger.rules

include $RULE_PATH/ftp.rules

include $RULE_PATH/telnet.rules

include $RULE_PATH/rpc.rules

include $RULE_PATH/rservices.rules

include $RULE_PATH/dos.rules

include $RULE_PATH/ddos.rules

include $RULE_PATH/dns.rules

include $RULE_PATH/tftp.rules

 

include $RULE_PATH/web-cgi.rules

include $RULE_PATH/web-coldfusion.rules

include $RULE_PATH/web-iis.rules

include $RULE_PATH/web-frontpage.rules

include $RULE_PATH/web-misc.rules

include $RULE_PATH/web-client.rules

include $RULE_PATH/web-php.rules

 

include $RULE_PATH/sql.rules

include $RULE_PATH/x11.rules

include $RULE_PATH/icmp.rules

include $RULE_PATH/netbios.rules

include $RULE_PATH/misc.rules

include $RULE_PATH/attack-responses.rules

include $RULE_PATH/oracle.rules

include $RULE_PATH/mysql.rules

include $RULE_PATH/snmp.rules

 

include $RULE_PATH/smtp.rules

include $RULE_PATH/imap.rules

include $RULE_PATH/pop2.rules

include $RULE_PATH/pop3.rules

 

include $RULE_PATH/nntp.rules

include $RULE_PATH/other-ids.rules

# include $RULE_PATH/web-attacks.rules

include $RULE_PATH/backdoor.rules

# include $RULE_PATH/shellcode.rules

include $RULE_PATH/policy.rules

# include $RULE_PATH/porn.rules

# include $RULE_PATH/info.rules

# include $RULE_PATH/icmp-info.rules

include $RULE_PATH/virus.rules

include $RULE_PATH/chat.rules

# include $RULE_PATH/multimedia.rules

include $RULE_PATH/p2p.rules

include $RULE_PATH/experimental.rules

 

include $RULE_PATH/spyware-put.rules

 

include $RULE_PATH/bleeding-policy.rules

include $RULE_PATH/bleeding-malware.rules

 

# Include any thresholding or suppression commands. See threshold.conf
in the

# <snort src>/etc directory for details. Commands don't necessarily need
to be

# contained in this conf, but a separate conf makes it easier to
maintain them. 

# Note for Windows users:  You are advised to make this an absolute
path,

# such as:  c:\snort\etc\threshold.conf

# Uncomment if needed.

# include threshold.conf

include /etc/snort/threshold.conf

 

 

Ron Jenkins (SnortCP, MCNE, CNE6, MCP, CCNA, CCEA)
Senior Architect
Data Integrity, LLC
"We Integrate People with Solutions"
1724 Dallas Drive
Suite 11
Baton Rouge, La 70806
Office. 225.927.8030
Fax. 225.927.8033
Cell225.931.1632

Email. rjenkins () dibr net
Web. http://www.dibr.net

(Aanval Reseller and Technology Partner)

http://www.aanval.com/tour/dibr

 

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