Help Center/ Anti-DDoS Service/ User Guide/ Advanced Anti-DDoS User Guide/ Configuring a Protection Policy/ Configuring CC Attack Protection Rules/ Configuring Frequency Control Rules
Updated on 2024-04-25 GMT+08:00
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Configuring Frequency Control Rules

Scenarios

You can set frequency control rules to limit the access frequency of a single IP address, cookie, or referer to the origin server of a protected website. You can also enable policy-based, domain name, and URL rate limiting to detect and block malicious traffic.

Prerequisites

Website services have been connected to AAD and Basic Web Protection has been enabled.

Procedure

  1. Log in to the management console.
  2. Select a region in the upper part of the page, click in the upper left corner of the page, and choose Security & Compliance > Anti-DDoS Service. The Anti-DDoS Service Center page is displayed.
  3. In the navigation pane on the left, choose Advanced Anti-DDoS > Protection Policies. The Protection Policies page is displayed.

    Figure 1 Advanced Anti-DDoS protection policies

  1. Click the Web Attack Protection tab.
  2. After selecting the region and objects, click Create frequency control rules.

    Figure 2 Frequency control rules

  3. Click Create frequency control rules.
  4. Configure the frequency control rule, as shown in Figure 3.

    Figure 3 Creating a frequency control rule
    Table 1 Parameter description

    Parameter

    Description

    Name

    Name of the rule

    Rate Limit Mode
    • Source: Requests from a specific source are limited. For example, if traffic from an IP address (or user) exceeds the rate limit you configure in this rule, WAF limits traffic rate of the IP address (or user) in the way you configure.
      • Per IP address: A web visitor is identified by the IP address.
      • Per user: A website visitor is identified by the key value of Cookie or Header.
      • Other: A web visitor is identified by the Referer field (user-defined request source).
        NOTE:

        If you set Rate Limit Mode to Other, set Content of Referer to a complete URL containing the domain name. The Content field supports prefix match and exact match only, but cannot contain two or more consecutive slashes, for example, ///admin. If you enter ///admin, WAF will convert it to /admin.

        For example, if you do not want visitors to access www.test.com, set Referer to http://www.test.com.

    • Destination: Requests to a specific destination are limited.
      • By rule: If this rule is used by multiple domain names, requests for all these domain names are counted for this rule no matter what IP addresses these requests originate from. If you have added a wildcard domain name to WAF, requests for all domain names matched the wildcard domain name are counted for triggering this rule no matter what IP addresses these requests originate from.
      • By domain name: Requests for each domain name are counted separately. If the number exceeds the threshold you configure, the protective action is triggered no matter what IP addresses these requests originate from.
      • By URL: Requests for each URL are counted separately. If the number exceeds the threshold you configure, the protective action is triggered no matter what IP addresses these requests originate from.

    Request Aggregation

    This parameter is not required when you select Destination and By rule for Rate Limit Mode.

    This function is disabled by default. Keep this function enabled so that requests to all domain names that match a protected wildcard domain are counted for triggering this rule. For example, if you added *.a.com, requests to all matched domain names such as b.a.com and c.a.com are counted.

    User Identifier

    This parameter is mandatory when you select Source and Per user for Rate Limit Mode.

    • Cookie: A cookie field name. You need to configure an attribute variable name in the cookie that can uniquely identify a web visitor based on your website requirements. This field does not support regular expressions. Only complete matches are supported.

      For example, if a website uses the name field in the cookie to uniquely identify a web visitor, enter name.

    • Header: Set the user-defined HTTP header you want to protect. You need to configure the HTTP header that can identify web visitors based on your website requirements.

    Trigger

    Click Add to add conditions. At least one condition is required, but up to 30 conditions are allowed. If you add more than one condition, the rule will only take effect if all of the conditions are met.

    • Field: Set this parameter based on the site requirements.
    • Subfield: Configure this field only when IPv4, IPv6, Cookie, Header, or Params is selected for Field.
    • Logic: Select the required logic from the drop-down list box.
    • Content: Enter or select the content that matches the condition.

    Rate Limit

    The number of requests allowed from a website visitor in the rate limit period. If the number of requests exceeds the rate limit, WAF takes the action you configure for Protective Action.

    All WAF instances: Requests to on one or more WAF instances will be counted together according to the rate limit mode you select. By default, requests to each WAF instance are counted. If you enable this, WAF will count requests to all your WAF instances for triggering this rule. To enable user-based rate limiting, Per user or Other (Referer must be configured) instead of Per IP address must be selected for Rate Limit Mode. This is because IP address-based rate limiting cannot limit the access rate of a specific user. However, in user-based rate limiting, requests may be forwarded to one or more WAF instances. Therefore, All WAF instances must be enabled for triggering the rule precisely.

    Protective Action

    The action that WAF will take if the number of requests exceeds Rate Limit you configured. The options are as follows:

    • Verification code: WAF allows requests that trigger the rule as long as your website visitors complete the required verification.
    • Block: WAF blocks requests that trigger the rule.
    • Block dynamically: WAF blocks requests that trigger the rule based on Allowable Frequency, which you configure after the first rate limit period is over.
    • Log only: WAF only logs requests that trigger the rule.

    Lock Verification

    This parameter is mandatory if Protective Action is set to Verification code.

    If a visitor fails verification code authentication, verification is required for all access requests within the specified period.

    Allowable Frequency

    This parameter can be set if you select Block dynamically for Protective Action.

    WAF blocks requests that trigger the rule based on Rate Limit first. Then, in the following rate limit period, WAF blocks requests that trigger the rule based on Allowable Frequency you configure.

    The Allowable Frequency must be less than or equal to the Rate Limit.

    Notification Window

    The default option is Immediately.

    Block Duration

    Period of time for which to block the item when you set Protective Action to Block.

    Block Page

    The page displayed if the request limit has been reached. This parameter is configured only when Protective Action is set to Block.

    • If you select Default settings, the default block page is displayed.
    • If you select Customize, customize a page to be displayed.

    Block Page Type

    If you select Custom for Block Page, select a type of the block page among options application/json, text/html, and text/xml.

    Page Content

    Specifies the content to be displayed on the page you will customize.

  5. Click OK.

Follow-up Operations

  • Enable frequency control protection: On the Web Attack Protection page, set Frequency Control to .
  • Disable frequency control protection: On the Web Attack Protection page, set Frequency Control to .