<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>ActivatedRule</a> objects in a <code>WebACL</code>. Each <code>Rule</code> identifies web requests that you want to allow, block, or count. When you update a <code>WebACL</code>, you specify the following values:</p> <ul> <li> <p>A default action for the <code>WebACL</code>, either <code>ALLOW</code> or <code>BLOCK</code>. AWS WAF performs the default action if a request doesn't match the criteria in any of the <code>Rules</code> in a <code>WebACL</code>.</p> </li> <li> <p>The <code>Rules</code> that you want to add or delete. If you want to replace one <code>Rule</code> with another, you delete the existing <code>Rule</code> and add the new one.</p> </li> <li> <p>For each <code>Rule</code>, whether you want AWS WAF to allow requests, block requests, or count requests that match the conditions in the <code>Rule</code>.</p> </li> <li> <p>The order in which you want AWS WAF to evaluate the <code>Rules</code> in a <code>WebACL</code>. If you add more than one <code>Rule</code> to a <code>WebACL</code>, AWS WAF evaluates each request against the <code>Rules</code> in order based on the value of <code>Priority</code>. (The <code>Rule</code> that has the lowest value for <code>Priority</code> is evaluated first.) When a web request matches all the predicates (such as <code>ByteMatchSets</code> and <code>IPSets</code>) in a <code>Rule</code>, AWS WAF immediately takes the corresponding action, allow or block, and doesn't evaluate the request against the remaining <code>Rules</code> in the <code>WebACL</code>, if any. </p> </li> </ul> <p>To create and configure a <code>WebACL</code>, perform the following steps:</p> <ol> <li> <p>Create and update the predicates that you want to include in <code>Rules</code>. For more information, see <a>CreateByteMatchSet</a>, <a>UpdateByteMatchSet</a>, <a>CreateIPSet</a>, <a>UpdateIPSet</a>, <a>CreateSqlInjectionMatchSet</a>, and <a>UpdateSqlInjectionMatchSet</a>.</p> </li> <li> <p>Create and update the <code>Rules</code> that you want to include in the <code>WebACL</code>. For more information, see <a>CreateRule</a> and <a>UpdateRule</a>.</p> </li> <li> <p>Create a <code>WebACL</code>. See <a>CreateWebACL</a>.</p> </li> <li> <p>Use <code>GetChangeToken</code> to get the change token that you provide in the <code>ChangeToken</code> parameter of an <a>UpdateWebACL</a> request.</p> </li> <li> <p>Submit an <code>UpdateWebACL</code> request to specify the <code>Rules</code> that you want to include in the <code>WebACL</code>, to specify the default action, and to associate the <code>WebACL</code> with a CloudFront distribution. </p> <p>The <code>ActivatedRule</code> can be a rule group. If you specify a rule group as your <code>ActivatedRule</code> , you can exclude specific rules from that rule group.</p> <p>If you already have a rule group associated with a web ACL and want to submit an <code>UpdateWebACL</code> request to exclude certain rules from that rule group, you must first remove the rule group from the web ACL, the re-insert it again, specifying the excluded rules. For details, see <a>ActivatedRule$ExcludedRules</a> . </p> </li> </ol> <p>Be aware that if you try to add a RATE_BASED rule to a web ACL without setting the rule type when first creating the rule, the <a>UpdateWebACL</a> request will fail because the request tries to add a REGULAR rule (the default rule type) with the specified ID, which does not exist. </p> <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>