Help Center/ Web Application Firewall/ User Guide (ME-Abu Dhabi Region) / Website Settings/ Adding a Website to WAF (Cloud Mode)/ Step 4: Modify the DNS Records of the Domain Name
Updated on 2024-03-14 GMT+08:00
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Step 4: Modify the DNS Records of the Domain Name

After a domain name is connected to WAF, WAF functions as a reverse proxy between the client and server. The real IP address of the server is hidden, and only the IP address of WAF is visible to web visitors. You must point the DNS resolution of the domain name to the CNAME record provided by WAF. In this way, access requests can be resolved to WAF.

To ensure that your WAF instance works properly, test it according to the instructions in Step 3: Test WAF before routing your business traffic to WAF.

Prerequisites

Constraints

WAF protection takes effect only for real client IP addresses where requests originate. To ensure that WAF obtains real client IP addresses, if your website has layer-7 proxies such as CDN and cloud acceleration products deployed in front of WAF, Yes must be selected for Proxy Configured.

Specification Limitations

After your website is connected to WAF, you can upload a file no larger than 10 GB each time.

How WAF Works

  • No proxy used

    DNS resolves your domain name to the origin server IP address before the site is connected to WAF. DNS resolves your domain name to the CNAME of WAF after the site is connected to WAF. Then WAF inspects the incoming traffic and filters out malicious traffic.

  • A proxy (such as anti-DDoS service) used

    If a proxy such as anti-DDoS service is used on your site before it is connected to WAF, DNS resolves the domain name of your site to the anti-DDoS IP address. The traffic goes to the anti-DDoS service and the anti-DDoS service then routes the traffic back to the origin server. After you connect your website to WAF, change the back-to-source address of the proxy (such as anti-DDoS service) to the CNAME of WAF. In this way, the proxy forwards the traffic to WAF. WAF then filters out illegitimate traffic and only routes legitimate traffic back to the origin server.

    • To ensure that WAF can properly forward requests, test WAF by referring to Testing WAF before modifying the DNS configuration.
    • To prevent other users from configuring your domain names on WAF in advance (this will cause interference on your domain name protection), add the subdomain name and TXT record on your DNS management platform. WAF can determine which user owns the domain name based on the subdomain name and TXT record.

Operation Guide

After a domain name is added, WAF generates a CNAME record, or CNAME, subdomain name, and TXT record for DNS to resolve the domain name to WAF so that website traffic can pass through WAF for detection. For details, see Table 1.

Table 1 Operation guide

Scenario

Generated Parameter Value

Operation Related to Domain Name Resolution

No proxy used

CNAME

The DNS obtains the CNAME of WAF.

Proxy used

CNAME, subdomain name, and TXT record
  • Change the back-to-source IP address of the proxy, such as anti-DDoS service, to the CNAME of WAF.
  • (Optional) Add a WAF subdomain name and TXT record at your DNS provider.

Procedure

  1. Log in to the management console.
  2. Click in the upper left corner of the management console and select a region or project.
  3. Click in the upper left corner and choose Web Application Firewall under Security.
  4. In the navigation pane on the left, choose Website Settings.
  5. In the row containing the desired domain name, click the domain name to go to the Basic Information page.
  6. In the CNAME row, click to copy the CNAME record.

    If the message "CNAME copied successfully" is displayed in the upper right corner of the page, the CNAME record is copied successfully.

  7. Connect the domain name to WAF.

    • No proxy used

      Configure the CNAME record at your DNS provider. For details, contact your DNS provider.

    • Proxy used

      Change the back-to-source IP address of the used proxy, such as anti-DDoS and CDN services, to the copied CNAME record.

      To prevent other users from configuring your domain names on WAF in advance (this will cause interference on your domain name protection), add the subdomain name and TXT record on your DNS management platform.

      1. Obtain Subdomain Name and TXT Record: In the row of Access Status, click How to Access. In the Access Guide dialog box, copy Subdomain Name and TXT Record.
      2. Add Subdomain Name at the DNS provider and configure TXT Record for the subdomain name.

      WAF determines which user owns the domain name based on the configured Subdomain Name and TXT Record.

  8. Verify that the CNAME of the domain name has been configured.

    1. In Windows, choose Start > Run. Then enter cmd and press Enter.
    2. Run a nslookup command to query the CNAME record.

      If the configured CNAME is returned, the configuration is successful.

      Example command:

      nslookup www.example.com

Follow-up Procedure

  • If your server uses other network firewalls, disable these network firewalls or add the WAF IP address range to the IP address whitelist of these network firewalls. Otherwise, these firewalls may regard the WAF IP address as a malicious IP address.
  • If your web server is using personal security software, replace it with enterprise security software and whitelist the WAF IP address ranges.

Verification

  • By default, WAF detects the Access Status of each protected domain name on an hourly basis.
  • Generally, if you have performed domain connection and Access Status is Accessible, the domain name is connected to WAF.