<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>Predicate</a> objects in a rule and updates the <code>RateLimit</code> in the rule. </p> <p>Each <code>Predicate</code> object identifies a predicate, such as a <a>ByteMatchSet</a> or an <a>IPSet</a>, that specifies the web requests that you want to block or count. The <code>RateLimit</code> specifies the number of requests every five minutes that triggers the rule.</p> <p>If you add more than one predicate to a <code>RateBasedRule</code>, a request must match all the predicates and exceed the <code>RateLimit</code> to be counted or blocked. For example, suppose you add the following to a <code>RateBasedRule</code>:</p> <ul> <li> <p>An <code>IPSet</code> that matches the IP address <code>192.0.2.44/32</code> </p> </li> <li> <p>A <code>ByteMatchSet</code> that matches <code>BadBot</code> in the <code>User-Agent</code> header</p> </li> </ul> <p>Further, you specify a <code>RateLimit</code> of 1,000.</p> <p>You then add the <code>RateBasedRule</code> to a <code>WebACL</code> and specify that you want to block requests that satisfy the rule. For a request to be blocked, it must come from the IP address 192.0.2.44 <i>and</i> the <code>User-Agent</code> header in the request must contain the value <code>BadBot</code>. Further, requests that match these two conditions much be received at a rate of more than 1,000 every five minutes. If the rate drops below this limit, AWS WAF no longer blocks the requests.</p> <p>As a second example, suppose you want to limit requests to a particular page on your site. To do this, you could add the following to a <code>RateBasedRule</code>:</p> <ul> <li> <p>A <code>ByteMatchSet</code> with <code>FieldToMatch</code> of <code>URI</code> </p> </li> <li> <p>A <code>PositionalConstraint</code> of <code>STARTS_WITH</code> </p> </li> <li> <p>A <code>TargetString</code> of <code>login</code> </p> </li> </ul> <p>Further, you specify a <code>RateLimit</code> of 1,000.</p> <p>By adding this <code>RateBasedRule</code> to a <code>WebACL</code>, you could limit requests to your login page without affecting the rest of your site.</p>