<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>Inserts or deletes <a>RegexMatchTuple</a> objects (filters) in a <a>RegexMatchSet</a>. For each <code>RegexMatchSetUpdate</code> object, you specify the following values: </p> <ul> <li> <p>Whether to insert or delete the object from the array. If you want to change a <code>RegexMatchSetUpdate</code> object, you delete the existing object and add a new one.</p> </li> <li> <p>The part of a web request that you want AWS WAF to inspectupdate, such as a query string or the value of the <code>User-Agent</code> header. </p> </li> <li> <p>The identifier of the pattern (a regular expression) that you want AWS WAF to look for. For more information, see <a>RegexPatternSet</a>. </p> </li> <li> <p>Whether to perform any conversions on the request, such as converting it to lowercase, before inspecting it for the specified string.</p> </li> </ul> <p> For example, you can create a <code>RegexPatternSet</code> that matches any requests with <code>User-Agent</code> headers that contain the string <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>RegexMatchSet</code>, perform the following steps:</p> <ol> <li> <p>Create a <code>RegexMatchSet.</code> For more information, see <a>CreateRegexMatchSet</a>.</p> </li> <li> <p>Use <a>GetChangeToken</a> to get the change token that you provide in the <code>ChangeToken</code> parameter of an <code>UpdateRegexMatchSet</code> request.</p> </li> <li> <p>Submit an <code>UpdateRegexMatchSet</code> request to specify the part of the request that you want AWS WAF to inspect (for example, the header or the URI) and the identifier of the <code>RegexPatternSet</code> that contain the regular expression patters 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>