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I'm trying to learn network intrusion detection. When I try to launch Snort, in IDS mode, I get this message (I'm running Mac OS X):

Initializing Network Interface en1
ERROR: OpenPcap() FSM compilation failed: 
    syntax error
PCAP command: snort
Fatal Error, Quitting..

How can I fix this problem?

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migrated from Feb 26 '10 at 1:56

This question came from our site for professional and enthusiast programmers.

A few things to try:

  1. Make sure you are running Snort as root (or a user with permissions to drop into promiscuous mode.)

  2. Make sure your configuration is valid. (snort -t -c snort.conf I believe.)

  3. If all else fails ask on the forums at They're helpful.

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