Appendix: Regular Expressions

Using Regular Expressions in Custom Sites

Select URLs are defined as Regular Expression only if the application or site URL is entered as a regular expression using the correct syntax.

The meaning of the asterisk ( * ) depends on its use.

• In regular expressions, the asterisk is a metacharacter for zero or more instances of the preceding character.
• Without regular expressions, the asterisk is a wildcard, for zero or more instances of any character.

For example, to block a domain that ends with "example.com" (such as www.example.com):

Regular Expression	.*\.example\.com
Wildcard	*.example.com	Important! If you use this string as a regular expression, policy install fails. The gateway cannot resolve the regular expression to a URL, because there is no preceding character to find.