After you add a TCP listener to a Classic Load Balancer (CLB) instance, you can add the listener ports of the instance to Web Application Firewall (WAF) to redirect traffic on the ports to WAF. This topic describes how to add a Layer 4 CLB instance to WAF.
Background information
After you add Elastic Compute Service (ECS) instances that are deployed in the same region to a CLB instance, CLB uses virtual IP addresses (VIPs) to combine the ECS instances into a high-performance, high-availability server pool. Then, CLB forwards inbound requests to the ECS instances based on forwarding rules. For more information, see What is CLB?
You can add a Layer 4 CLB instance to WAF for protection. After you add a Layer 4 CLB instance to WAF, all traffic of the CLB instance is redirected to WAF by a specific gateway. WAF filters out malicious traffic and forwards normal traffic to the CLB instance. The following figure shows the network architecture.
Limits
You can add web services to WAF in cloud native mode only if your web services use one of the following Alibaba Cloud services: Application Load Balancer (ALB), Microservices Engine (MSE), Function Compute, Serverless App Engine (SAE), Classic Load Balancer (CLB), and Elastic Compute Service (ECS). If your web services do not use the preceding services, you can add the domain name of your website to WAF in CNAME record mode. For more information, see Add a domain name to WAF.
Item | Description |
Supported instances | To add an instance to WAF, the instance must meet the following requirements:
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Supported regions |
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Number of traffic redirection ports | The limits on the number of traffic redirection ports are the same as the limits on the number of protected objects.
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Services that are protected by Anti-DDoS Proxy and WAF | If you want to protect your web services by using Anti-DDoS Proxy and WAF, you can add the web services to WAF in transparent proxy mode only if you add the web services to Anti-DDoS Proxy by adding a domain name. |
Prerequisites
A WAF 3.0 instance is purchased. For more information, see Purchase a subscription WAF 3.0 instance and Purchase a pay-as-you-go WAF 3.0 instance.
A CLB instance that meets the requirements is created. A TCP listener is added to the CLB instance. For more information about the requirements, see Limits. For more information about how to add a TCP listener to a CLB instance, see Add a TCP listener.
If you use a subscription WAF instance, make sure that the number of protected objects that you add to WAF does not exceed the upper limit. If the number of protected objects that you add to WAF exceeds the upper limit, you can no longer add cloud service instances to WAF.
To view the number of protected objects that you can add to WAF, go to the Protected Objects page.
Add traffic redirection ports
The first time you add an instance to WAF, web services may be interrupted for several seconds. If clients can be automatically reconnected, the web services automatically resume. Configure reconnection mechanisms and back-to-origin settings based on your business requirements.
If you perform the following operations after you add a Layer 4 CLB instance or ECS instance to WAF, traffic redirection ports are automatically removed from WAF. If you do not re-add the traffic redirection ports to WAF, traffic on the ports is not redirected to WAF.
Change the public IP address of the instance.
Enable mutual authentication.
Log on to the WAF 3.0 console. In the top navigation bar, select the resource group and the region in which the WAF instance is deployed. You can select Chinese Mainland or Outside Chinese Mainland for the region.
In the left-side navigation pane, click Website Configuration.
On the Cloud Native tab, click CLB(TCP) in the left-side cloud service list.
Click Add.
Click Authorize Now to authorize your WAF instance to access CLB.
Alibaba Cloud automatically creates the AliyunServiceRoleForWAF service-linked role. To view the service-linked role, log on to the Resource Access Management (RAM) console and choose in the left-side navigation pane.
NoteIf you already authorized your WAF instance to access CLB, skip this step.
In the Configure Instance - Layer 4 CLB Instance panel, configure the parameters. The following table describes the parameters.
Parameter
Operation
Select the instance and port to be added.
(Optional) Synchronize Instances
If the instance that you want to add to WAF is not in the instance list, click Synchronize Instances to refresh the instance list.
Add Port
Find the instance that you want to add to WAF and click Add Port in the Actions column.
Select the ports that you want to add to WAF.
Select the protocol type of the ports that you want to add to WAF. Valid values: HTTP and HTTPS.
If you select HTTPS, you must upload a certificate.
NoteThe total number of default and additional certificates that you upload cannot exceed 10.
Default Certificate
If you select HTTPS, you can click Advanced Settings to configure the following advanced settings:
Whether Layer 7 Proxy, Such as Anti-DDoS Pro, Anti-DDoS Premium, or Alibaba Cloud CDN, Is Deployed in Front of WAF
Specify whether a Layer 7 proxy, such as Anti-DDoS Proxy and Alibaba Cloud CDN, is deployed in front of WAF. Valid values: Yes and No.
By default, No is selected. This value specifies that WAF receives requests that are sent from clients. The requests are not forwarded by proxies.
NoteWAF uses the IP address that is used to establish connections with WAF as the IP address of a client. WAF obtains the IP address from the
REMOTE_ADDR
field of the request.If Layer 7 proxies are deployed in front of WAF, select Yes. This value specifies that WAF receives requests that are forwarded to WAF by a Layer 7 proxy. To ensure that WAF can obtain the actual IP addresses of clients for security analysis, configure the Obtain Actual IP Address of Client parameter.
Resource Group
Select the resource group to which you want to add the instance. If you do not select a resource group, the instance is added to the default resource group.
NoteYou can use Resource Management to create resource groups and manage resources within your Alibaba Cloud account by department or project. For more information, see Create a resource group.
Advanced Settings
Select the CLB instance that you want to add to WAF and click OK.
After you add a CLB instance to WAF, the instance automatically becomes a protected object of WAF. The name of a protected object is in the following format: Instance ID-Port-Asset type. Basic protection rules are automatically enabled for the CLB instance. You can configure protection rules for the protected object on the Protected Objects page. To go to the Protected Objects page, click the ID of the CLB instance that you added to WAF on the Cloud Native tab of the Website Configuration page. For more information, see Protection configuration overview.
Other operations
View origin servers and manage traffic redirection ports
After you add a CLB instance to WAF, you can view the protection details of the origin servers and forcibly disable traffic redirection or remove traffic redirection ports in emergency disaster recovery scenarios.
On the Website Configuration page, click the Cloud Native tab.
In the left-side cloud service list, click CLB(TCP). Find the CLB instance whose traffic redirection ports you want to view and click the icon to the left of the instance name to view the ports that are added to WAF.
View port details: Click Port Details in the Actions column to view information about the port, protocol, and certificate. Then, configure the following parameters: Whether Layer 7 Proxy, Such as Anti-DDoS Pro, Anti-DDoS Premium, or Alibaba Cloud CDN, Is Deployed in Front of WAF, Enable Traffic Mark (Advanced Settings), and Back-to-origin Keep-alive Requests (Advanced Settings).
Remove ports: Click Remove and then click OK in the Remove message.
ImportantAfter you remove a traffic redirection port, traffic on the port is no longer protected by WAF. To re-add the port to WAF, click Add. For more information, see Add traffic redirection ports.
Update the SSL certificate bound to a traffic redirection port
If the SSL certificate that is bound to a traffic redirection port is about to expire or the certificate is changed, you must update the certificate.
If the remaining validity period of the certificate is less than 30 days, is displayed in the domain name list. This indicates that your SSL certificate is about to expire. You must update the certificate at the earliest opportunity.
If you want to receive notifications when the certificate is about to expire, log on to the Certificate Management Service console. Find the certificate that is about to expire and click the icon in the Notification Reminder column. On the Notification page, enable and configure a notification policy for the certificate.
To prevent service interruptions that are caused by certificate expiration, enable the certificate hosting feature of Certificate Management Service. If you enable this feature for a certificate, the system automatically applies for a new certificate. For more information, see Certificate Management Service overview.
To update the SSL certificate that is bound to a traffic redirection port, perform the following steps:
Renew the certificate or upload a third-party certificate to Certificate Management Service. For more information, see Certificate renewal or Upload an SSL certificate.
Synchronize the certificate to WAF.
In the Certificate Management Service console, deploy the certificate to WAF. For more information, see Deploy certificates to Alibaba Cloud services.
Update the certificate in the WAF console.
On the Cloud Native tab, click CLB(TCP) in the left-side cloud service list. Find the instance for which you want to update the certificate, click the icon, and then click Modify in the Actions column.
In the Default Certificate dialog box, select Select Existing Certificate and then select the new certificate from the drop-down list.