<note> <p>This is <b>AWS WAF Classic</b> documentation. For more information, see <a href="https://docs.aws.amazon.com/waf/latest/developerguide/classic-waf-chapter.html">AWS WAF Classic</a> in the developer guide.</p> <p> <b>For the latest version of AWS WAF</b>, use the AWS WAFV2 API and see the <a href="https://docs.aws.amazon.com/waf/latest/developerguide/waf-chapter.html">AWS WAF Developer Guide</a>. With the latest version, AWS WAF has a single set of endpoints for regional and global use. </p> </note> <p>Creates a <code>RegexPatternSet</code>. You then use <a>UpdateRegexPatternSet</a> to specify the regular expression (regex) pattern that you want AWS WAF to search for, such as <code>B[a@]dB[o0]t</code>. You can then configure AWS WAF to reject those requests.</p> <p>To create and configure a <code>RegexPatternSet</code>, perform the following steps:</p> <ol> <li> <p>Use <a>GetChangeToken</a> to get the change token that you provide in the <code>ChangeToken</code> parameter of a <code>CreateRegexPatternSet</code> request.</p> </li> <li> <p>Submit a <code>CreateRegexPatternSet</code> request.</p> </li> <li> <p>Use <code>GetChangeToken</code> to get the change token that you provide in the <code>ChangeToken</code> parameter of an <code>UpdateRegexPatternSet</code> request.</p> </li> <li> <p>Submit an <a>UpdateRegexPatternSet</a> request to specify the string that you want AWS WAF to watch for.</p> </li> </ol> <p>For more information about how to use the AWS WAF API to allow or block HTTP requests, see the <a href="https://docs.aws.amazon.com/waf/latest/developerguide/">AWS WAF Developer Guide</a>.</p>