RE: flags

[James Ashton <admin () gitflorida com>]

Here is snort.conf

I am building a new, faster box to run on this network. I am basicaly learning with this one. I had  hopoed that the 266
would cover a network that doesnt see much traffic, like this one. I have also cut a few rules out of  some of the 
rules files.
maybe 4 or 5 total. nothing that makes a noticable differance. Just top get rid of alerts I was not  worried about that
cluttered up the database.

My original question stands though. Why do the   -A fast -b   flags actualy slow snort down. When run with those flags 
this 
box goes from reading one out of every 8 packets  to reading one out of every 15 or so.

Again, snort is stared by the command:     snort -c /etc/snort/snort.conf -i eth0 -D



James Ashton

###################################################
# 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.
#
# 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 [A.B.C.D/24]

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

var EXTERNAL_NET any

# Set up your SMTP servers, or simply configure them
# to HOME_NET

var SMTP $HOME_NET

# Set up your web servers, or simply configure them
# to HOME_NET

var HTTP_SERVERS $HOME_NET

# Set up your sql servers, or simply configure them
# to HOME_NET

var SQL_SERVERS $HOME_NET

# Define the addresses of DNS servers and other hosts
# if you want to ignore portscan false alarms from them...

var DNS_SERVERS [a.b.c.d, e.f.g.h]

###################################################
# Step #2: Configure preprocessors
#
# General configuration for preprocessors is of
# the form
# preprocessor <name_of_processor>: <configuration_options>

# minfrag: detect small fragments
# -------------------------------
# minfrag has been deprecated as of build 26

# defrag: defragmentation support
# -------------------------------
# IP defragmentation support from Dragos Ruiu. There
# are no configuration options at this time.

#preprocessor defrag
preprocessor frag2: timeout 15

# stream2: TCP stream reassembly
# -------------------------------------
# TCP stream reassembly preprocessor from Chris Cramer.
# This preprocessor should always go after the defrag
# preprocessor, but before application layer decoders.
# The example below monitors ports 23 and 80, has a
# timeout after 10 seconds, and will send reassembled
# packets of max payload 16384 bytes through the
# detection engine. See README.tcpstream for more
# information and configuration options. Uncomment
# the following line and configure appropriately to
# enable this preprocessor.
#
# NOTE: This code should still be considered BETA!
# It seems to be stable, but there are still some
# issues that remain to be resolved, so make sure you
# keep an eye on your Snort sensor if you enable this plugin
# The older version which definitely had issues w/ packet
# loss is still in the code base, to use it in place of the
# new version, use "preprocessor stream: ..."

#preprocessor stream2: timeout 23, ports 21 23 80 110 143, maxbytes 16384

# 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 8MB)
# 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
#   keepstats [machine] - keep session statistics, add "machine" to get them in
#                         a flat format for machine reading
#   noinspect - turn off stateful inspection only
#   timeout [number] - set the session timeout counter to [number] seconds,
#                      default is 30 seconds
#   memcap [number] - limit stream4 memory usage to [number] bytes

preprocessor stream4: detect_scan, timeout 15, memcap 17572864

# 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, 53, 80, 143, 110, 111
#                  and 513

preprocessor stream4_reassemble both, ports [21, 23, 25, 53, 80, 143, 110, 111,
513]

# http_decode: normalize HTTP requests
# ------------------------------------
# http_decode normalizes HTTP requests from remote
# machines by converting any %XX character
# substitutions to their ASCII equivalent. This is
# very useful for doing things like defeating hostile
# attackers trying to stealth themselves from IDSs by
# mixing these substitutions in with the request.
# Specify the port numbers you want it to analyze as arguments.
# You may also specify -unicode to turn off detection of
# UNICODE directory traversal, etc attacks.  Use -cginull to
# turn off detection of CGI NULL code attacks.

preprocessor http_decode: 80 2301 -unicode -cginull

# unidecode: normalize HTTP/detect UNICODE attacks
# ------------------------------------------------
# Works much the same as http_decode, but does a better
# job of categorizing and identifying UNICODE attacks,
# recommended as a potential replacement for http_decode.

# preprocessor unidecode: 80 -unicode -cginull

# rpc_decode: normalize RPC traffic
# ---------------------------------
# RPC may be sent in alternate encodings besides the usual
# 4-byte encoding that is used by default.  This preprocessor
# normalized RPC traffic in much the same way as the http_decode
# preprocessor.  This plugin takes the ports numbers that RPC
# services are running on as arguments.

#preprocessor rpc_decode: 111

# bo: Back Orifice detector
# -------------------------
# Detects Back Orifice traffic on the network.  This preprocessor
# uses the Back Orifice "encryption" algorithm to search for
# traffic conforming to the Back Orifice protocol (not BO2K).
# This preprocessor can take two arguments.  The first is "-nobrute"
# which turns off the plugin's brute forcing routine (brute forces
# the key space of the protocol to find BO traffic).  The second
# argument that can be passed to the routine is a number to use
# as the default key when trying to decrypt the traffic.  The
# default value is 31337 (just like BO).  Be aware that turning on
# the brute forcing option runs the risk of impacting the overall
# performance of Snort, you've been warned...

#preprocessor bo: -nobrute

# 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.

#preprocessor telnet_decode

# portscan: detect a variety of portscans
# ---------------------------------------
# portscan preprocessor by Patrick Mullen <p_mullen () linuxrc net>
# This preprocessor detects UDP packets or TCP SYN packets going to
# four different ports in less than three seconds. "Stealth" TCP
# packets are always detected, regardless of these settings.

preprocessor portscan: $HOME_NET 5 5 portscan.log

# Use portscan-ignorehosts to ignore TCP SYN and UDP "scans" from
# specific networks or hosts to reduce false alerts. It is typical
# to see many false alerts from DNS servers so you may want to
# add your DNS servers here. You can all multiple hosts/networks
# in a whitespace-delimited list.
#
preprocessor portscan-ignorehosts: $DNS_SERVERS

# Spade: the Statistical Packet Anomaly Detection Engine
#-------------------------------------------------------
# READ the README.Spade file before using this plugin!
#
# See http://www.silicondefense.com/spice/ for more info
#
# Spade is a Snort plugin to report unusual, possibly
# suspicious, packets. Spade will review the packets
# received by Snort, find those of interest (TCP SYNs
# into your homenets, if any), and report those packets
# that it believes are anomalous along with an anomaly
# score.  To enable spp_anomsensor, you must have a
# line of this form in your snort configuration file:
#
# preprocessor spade: <anom-report-thresh> <state-file>
# <log-file> <prob-mode> <checkpoint-freq>  [-corrscore]
#
# set this to a directory Spade can read and write to
# store its files
#
# var SPADEDIR .
#
# preprocessor spade: -1 $SPADEDIR/spade.rcv $SPADEDIR/log.txt 3 50000
#
# put a list of the networks you are interested in Spade observing packets
# going to here; separate these by spaces
#
# preprocessor spade-homenet: 0.0.0.0/0
#
# this causes Spade to adjust the reporting threshold automatically
# the first argument is the target rate of alerts for normal circumstances
# (0.01 = 1% or you can give it an hourly rate) after the first hour (or
# however long the period is set to in the second argument), the reporting
# threshold given above is ignored you can comment this out to have the
# threshold be static, or try one of the other adapt methods below
# preprocessor spade-adapt3: 0.01 60 168
#
# other possible Spade config lines:
# adapt method #1
#preprocessor spade-adapt: 20 2 0.5
# adapt method #2
#preprocessor spade-adapt2: 0.01 15 4 24 7
# offline threshold learning
#preprocessor spade-threshlearn: 200 24
# periodically report on the anom scores and count of packets seen
#preprocessor spade-survey:  $SPADEDIR/survey.txt 60
# print out known stats about packet feature
#preprocessor spade-stats: entropy uncondprob condprob

# 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.

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

####################################################################
# Step #3: 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
#
# output alert_syslog: LOG_AUTH LOG_ALERT

# log_tcpdump: log packets in binary tcpdump format
# -------------------------------------------------
# The only argument is the output file name.
#
# output log_tcpdump: snort.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=snort password=snort dbname=snort2 host=loca
lhost
# output database: alert, postgresql, user=snort dbname=snort
# output database: log, unixodbc, user=snort dbname=snort
# output database: log, mssql, dbname=snort user=snort password=test

# xml: xml logging
# ----------------
# See the README.xml file for more information about configuring
# and using this plugin.
#
# output xml: log, file=/var/log/snortxml

# 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

# trap_snmp: SNMP alerting for Snort
# -------------------------------------------------------------
# Read the README-SNMP file for more information on enabling and using this
# plug-in.
#
#
# The SnmpTrapGenerator outputplugin requires several parameters
# The parameters depend on the Snmpversion that is used (specified)
# For the SNMPv2c case the paremeters will be as follows
#  alert, <sensorID>, {trap|inform} -v <SnmpVersion> -p <portNumber>
#         <hostName> <community>
#
# For SNMPv2c traps
#
#output trap_snmp: alert, 7, trap -v 2c -p 162  myTrapListener myCommunity
#
# For SNMPv2c informs

#output trap_snmp: alert, 7, inform -v 2c -p 162  myTrapListener myCommunity
#
# For SNMPv3 traps with
# security name = snortUser
# security level = authentication and privacy
# authentication parameters :
#           authentication protocol = SHA ,
#           authentication pass phrase = SnortAuthPassword
# privacy (encryption) parameters
#           privacy protocol = DES,
#           privacy pass phrase = SnortPrivPassword
#
#output trap_snmp: alert, 7, trap -v 3 -p 162 -u snortUser -l authPriv -a SHA -A
 SnortAuthPassword -x DES -X SnortPrivPassword myTrapListener
#For SNMPv3 informs with authentication and encryption
#output trap_snmp: alert, 7, inform -v 3 -p 162 -u snortUser -l authPriv -a SHA
-A SnortAuthPassword -x DES -X SnortPrivPassword myTrapListener

# 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 $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 $HOME_NET any -> $EXTERNAL_NET 31337 (msg:"Someone is being LEET"; \
#   flags:A+;)

#
# Include classification & priority settings
#

#include classification.config

####################################################################
# Step #4: 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.
#
# The rules included with this distribution generate alerts based on
# on suspicious activity. Depending on your network environment, your
# security policies, and what you consider to be suspicious, some of
# these rules may either generate false positives ore may be detecting
# activity you consider to be acceptable; therefore, you are
# encouraged to comment out rules that are not applicable in your
# environment.
#
# Note that using all of the rules at the same time may lead to
# serious packet loss on slower machines. YMMV, use with caution,
# standard disclaimers apply. :)
#
# The following individuals contributed many of rules in this
# distribution.
#
# Credits:
#   Ron Gula <rgula () securitywizards com> of Network Security Wizards
#   Max Vision <vision () whitehats com>
#   Martin Markgraf <martin () mail du gtn com>
#   CyberPsychotic <fygrave () tigerteam net>
#   Nick Rogness <nick () rapidnet com>
#   Jim Forster <jforster () rapidnet com>
#   Scott McIntyre <scott () whoi edu>
#   Tom Vandepoel <Tom.Vandepoel () ubizen com>
#   Brian Caswell <bmc () snort org>
#   Zeno <admin () cgisecurity com>
#
#=========================================
# Include all relevant rulesets here
#
# shellcode, policy, info, backdoor, and virus rulesets are
# disabled by default.  These require tuning and maintance.
# Please read the included specific file for more information.
#=========================================

include bad-traffic.rules
include exploit.rules
#include scan.rules
include finger.rules
include ftp.rules
include telnet.rules
#include smtp.rules
#include rpc.rules
#include rservices.rules
include dos.rules
#include ddos.rules
#include dns.rules
include tftp.rules
include web-cgi.rules
#include web-coldfusion.rules
#include web-frontpage.rules
include web-iis.rules
include web-misc.rules
include web-attacks.rules
#include sql.rules
#include x11.rules
#include icmp.rules
#include netbios.rules
include misc.rules
include attack-responses.rules
include backdoor.rules
#include shellcode.rules
#include policy.rules
#include porn.rules
#include info.rules
#include icmp-info.rules
#include virus.rules
#include local.rules


_______________________________
James Ashton
Network Admin / Chief of client monitoring

Global Internet Tech, Inc
13840 Osprey Links Dr, #219
Orlando Fl, 32837

407-859-5218  



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