All of the whitelist properties accept regular expressions to define sets of IP, host or domain name addresses using wildcards. You can use any valid regular expression character, however, the most common wildcard characters that you may use are:

Examples and solutions for the most common patterns include:

Because the dot character is used as a wildcard in regular expressions and is also the standard separator for groups in IP addresses, domain names and host names, you can get unintended results when using wildcards. For example, this is a valid regular expression for IP addresses:

On Windows systems, many administrators would expect this to expression to "match any IP address with first-through-third groups of 139, 16 and 1 respectively" such as 139.16.1.10 and 139.16.1.35.

This would actually match either of these IP addresses:

In most cases, the difference between a literal dot and the dot as a wildcard character doesn’t make a difference. If you need to clarify a whitelist entry to match a literal dot, use \. instead.

The expression 139\.16\.1\..* would correctly match 139.16.1.10 and 139.16.1.35 but would not match 139.16.11.120. In many cases, you could also simplify this to 139.16.1\..* to get the correct behavior.

With domains, you must specify a wildcard at the beginning of the domain name. This example is not a valid domain name expression:

This entry would not match a host name of east.mydomain.com or east.customers.mydomain.com. To specify the domain correctly, enter:

In whitelist properties, host names are fully-qualified. Thus stives is not a valid host name while stives.customers.mydomain.com is valid. A host name expression of .*customers.mydomain.com would match all of these hosts:

Note that an expression of .*.customers.mydomain.com would also match these same three hosts.

You may need to specify literal dot separators in host names also to properly clarify the expressions. If in this example you did not want tempcustomers.mydomain.com to be matched, you would need an expression such as .*\.customers.mydomain.com. See Specifying Literal Dot Separators for more information.