[Snort-users] Problem running Snort Inline

Anshuman Anil Deshmukh anshuman at ...16510...
Thu Feb 5 01:40:16 EST 2015


We have issues running Snort inline. This is the exact problem which is mentioned here - http://www.linuxforums.org/forum/debian-linux/200751-snort-inline.html (see log below).

We have setup the Snort inline (version which is compiled using switch --enable-sourcefire.

It says "Enabling inline operation" and then switches to IDS mode.

Our command line for running Snort:
/usr/local/snort/bin/snort -c /usr/local/snort/etc/snort_conf_rules.conf -i eth0:eth1 -Q --pid-path=/var/run which creates the bridge automatically. Both the interfaces doesn't have IP addresses assigned.

We have already enabled following options for snort inline:

config policy_mode:inline

config daq: afpacket

config daq_mode: inline

config daq_var: buffer_size_mb=1024

preprocessor normalize_ip4

preprocessor normalize_tcp: ips ecn stream

preprocessor normalize_icmp4

preprocessor normalize_ip6

preprocessor normalize_icmp6

Under verdicts it shows 0% packets blocked. We have enabled couple of drop rules for BRUTE FORCE attack one of which is getting detected. Here is the snort output.
02/02-12:12:23.042082  [Drop] [**] [1:2019876:2] ET SCAN SSH BruteForce Tool with fake PUTTY version [**] [Classification: Detection of a Network Scan] [Priority: 3] {TCP} -> 00.00.00.:22 (IP addresses information removed)

But under verdicts it shows nothing blocked. Why??

      Allow:      4335107 ( 59.187%)
      Block:            0 (  0.000%)

Output says:
Enabling inline operation
Running in IDS mode

        --== Initializing Snort ==--
Initializing Output Plugins!
Initializing Preprocessors!
Initializing Plug-ins!

Information about our setup-

   ,,_     -*> Snort! <*-
  o"  )~   Version GRE (Build 149)
   ''''    By Martin Roesch & The Snort Team: http://www.snort.org/contact#team
           Copyright (C) 2014 Cisco and/or its affiliates. All rights reserved.
           Copyright (C) 1998-2013 Sourcefire, Inc., et al.
           Using libpcap version 1.4.0
           Using PCRE version: 7.8 2008-09-05
           Using ZLIB version: 1.2.3


/usr/local/snort/bin/snort --daq-list
Available DAQ modules:
pcap(v3): readback live multi unpriv
ipfw(v3): live inline multi unpriv
dump(v2): readback live inline multi unpriv
afpacket(v5): live inline multi unpriv


Please let me know in case any other information is required.


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