TekTip ep12 - Regex Basics

Description: Regular expressions are a way to match specific patterns in strings.

Demo Setup: For the demo, I am using BT5 with eclipse and pydev.  I am demonstrating with python, but there are many other methods that could be used.

Uses:  Singature creation pcre, scripting, programming

"\w": word character

"\W": Not word character

"\d" : digit

"\D" : Not digit

"\s" : space

"\S" : not space

"\" : escape 

"." : Any character except \n (new line)

"|" : or

"{}" : Range

"+" : One or more

Examples:

String: Hi, my name is 1aN0rmus.  My phone number is 555-555-5555 my address is 123 Internet Lane. 

Regex: '\d\w\w\d\w\w\w\w'

Result: 1aN0rmus

Regex: '\d\w+\d\w+'

Result: 1aN0rmus

Regex: '\d{3}.\d{3}.\d{4}'

Result: 555.555.5555 

Regex: '\d{1,5}\s\w+\s\w+'

Result: 123 Internet Lane

String: saDaSDASD/forum/Themes/core/images/sdfs.exe SAdasd

Regex: '\/forum\/Themes\/core\/images\/\w+\.exe'

Result: /forum/Themes/core/images/sdfs.exe

Scripts seen on this episode can be downloaded at https://github.com/1aN0rmus/TekDefense.  Feel free to help out with either script.  I'm a beginner when it comes to python.

Thank you,

1aN0rmus@tekdefense.com

http://www.securitytube.net/user/1aN0rmus

www.youtube.com/user/TekDefense