All the tables provided in the cheat sheets are also presented in tables below which are easy to copy and paste.

The Snort Cheat Sheet covers:

  • Sniffer mode, Packet logger mode, and NIDS mode operation
  • Snort rules format
  • Logger mode command line options
  • NIDS mode options
  • Alert and rule examples

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Snort Cheat Sheet

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What’s included in this cheat sheet

The following categories and items have been included in the cheat sheet:

Sniffer Mode

Sniffer Mode


Sniff packets and send to standard output as a dump file


-v (verbose)


Display output on the screen


–e


Display link layer headers


–d


Display packet data payload


–x


Display full packet with headers in HEX format


Packet Logger Mode

Packet Logger Mode


Input output to a log file


-r


Use to read back the log file content using snort


–l (directory name)


Log to a directory as a tcpdump file format


–k (ASCII)


Display output as ASCII format


NIDS Mode


NIDS Mode



Use the specified file as config file and apply 


rules to process captured packets



–c



Define configuration file path



–T 



Use to test the configuration file including rules


Snort rules format

Snort Rules Format


Rule Header + (Rule Options)


Action - Protocol - Source/Destination IP's - Source/Destination Ports - Direction of the flow


Alert Example


alert udp !10.1.1.0/24 any -> 10.2.0.0/24 any


Actions


alert, log, pass, activate, dynamic, drop, reject, sdrop


Protocols


TCP, UDP, ICMP, IP


Logger mode command line options

Logger Mode command line options


-l logdir


Log packets in tcp dump


-K ASCII


Log in ASCII format


NIDS mode options

NIDS Mode Options


Define a configuration file


-c ( Configuration file name)


Check the rule syntax and format for accuracy


-T –c (Configuration file name )


Alternate alert modes


-A (Mode : Full, Fast, None ,Console)


Alert to syslog


-s


Print alert information


-v


Send SMB alert to PC


-M (PC name or IP address)


ASCII log mode


-K


No logging


-N


Run in Background


-D


Listen to a specific network interface


-i


Snort rule example

Snort Rule Example


log tcp !10.1.1.0/24 any -> 10.1.1.100 (msg: "ftp access";)


Output Default Directory

Output Default Directory


/var/snort/log