snort.conf

关于网络渗透技术的详细讲解

#   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.
# Portscan uses Generator ID 109 and does not generate any SID currently.

preprocessor telnet_decode

# 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.
#
preprocessor sfportscan: proto  { all } \