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Edge Security Acceleration:Overview of WAF

Last Updated:Jun 16, 2026

DCDN integrates Web Application Firewall (WAF) capabilities at DCDN points of presence (POPs) to identify malicious traffic and intercept malicious requests.

Important

Alibaba Cloud DCDN will stop offering the WAF protection feature to new users starting at 00:00 (UTC+8) on May 1, 2025. Users who have already enabled the service are not affected.

If you need this feature, we recommend that you upgrade to ESA Edge Security Acceleration service. The WAF protection of ESA provides better protection than the WAF of DCDN.

Benefits

WAF deeply integrates the core WAF engine into DCDN points of presence (POPs). The redesigned console workflow improves security O&M efficiency, streamlines the user experience, and expands website protection options.

Compared to previous WAF versions, the new WAF offers the following advantages:

  • New cloud-native architecture:

    The WAF engine is deeply integrated into DCDN POPs. All traffic to your domain names passes through WAF, ensuring that features such as the web regular expression engine and custom rules are enforced at the edge for comprehensive protection.

  • New protection configuration model:

    WAF uses a flexible policy configuration model. You can apply protection policies and rules to multiple domain names in batches, significantly improving configuration efficiency.

    Note
    • A protected domain name is a domain name with the WAF feature enabled.

    • A protection policy is a collection of protection rules. You can configure a default policy to apply a predefined set of rules to all newly protected domain names. You can also customize protection policies to meet specific requirements.

    • A protection rule is a specific rule defined within a protection policy. Examples include the medium-level rule group for web regular expression protection and access control rules within a custom policy.

  • New pay-as-you-go billing model:

    WAF uses a pay-as-you-go billing model with the Security Capacity Unit (SeCU) as the standard unit of measurement. All billable items are converted into SeCUs, lowering the billing threshold and simplifying billing. Bills are generated hourly based on SeCU usage.

WAF features

The following table lists the protection features that WAF supports.

Feature

Sub-feature

WAF support

Domain name management

Configuration management

Supported

Whitelist

Whitelist for precise access control

Supported

Web security

Regular expression protection

Zero-day rule updates

Supported

Warning and block modes

Anti-obfuscation decoding

Supported

Custom regular expression protection rule groups

Supported

Access control/throttling

IP blacklist

Supported

Region blacklist

Supported

Custom protection policies

Supported

Scan protection

Supported

Monitoring and reports

Overview and reports

Supported

Log service

Real-time log

Supported

Bot management

Allowed bots

Supported

Bot threat intelligence

Supported

Intelligent bot algorithm

Supported

App protection

Supported

Response actions

CAPTCHA and custom responses

Supported

Billing

WAF uses the Security Capacity Unit (SeCU) as its billing unit and supports both a pay-as-you-go model and payment via a resource plan. For more information, see Billing of WAF.

Note

To purchase a WAF resource plan, click here.

Edge WAF parameter injection

When Edge WAF rules take effect, DCDN injects parameters into client requests for JavaScript verification, CAPTCHA challenges, and enhanced protection. The following table lists the injected parameters by protection type and injection location.

Protection type

Injected parameters

Injection location

All WAF rules

acw_tcb, cdn_sec_tc

Cookie

JavaScript verification

acw_sc__v2

Cookie, query string

Dynamic token challenge

timestamp__, md5__, type__, alichlgref

Query string

Slider CAPTCHA

u_atoken, u_asession, u_asig, u_aref, acw_sc__v3

u_atoken, u_asession, u_asig, u_aref to query string; acw_sc__v3 to cookie

Bot management: web page/browser protection

ssxmod_itna, ssxmod_itna2

Cookie, query string

Bot management: mini program protection

ssxmod_itna3

Cookie

Bot management: app protection

wtoken, ali_sign_whash

wtoken to header; ali_sign_whash to query string, header, and cookie