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# AWS::WAFv2::WebACL ForwardedIPConfiguration
<a name="aws-properties-wafv2-webacl-forwardedipconfiguration"></a>

The configuration for inspecting IP addresses in an HTTP header that you specify, instead of using the IP address that's reported by the web request origin. Commonly, this is the X-Forwarded-For (XFF) header, but you can specify any header name. 

**Note**  
If the specified header isn't present in the request, Amazon WAF doesn't apply the rule to the web request at all.

This configuration is used for [GeoMatchStatement](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/aws-properties-wafv2-webacl-statement.html#cfn-wafv2-webacl-statement-geomatchstatement), [AsnMatchStatement](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/aws-properties-wafv2-webacl-statement.html#cfn-wafv2-webacl-statement-asnmatchstatement), and [RateBasedStatement](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/aws-properties-wafv2-webacl-statement.html#cfn-wafv2-webacl-statement-ratebasedstatement). For [IPSetReferenceStatement](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/aws-properties-wafv2-webacl-statement.html#cfn-wafv2-webacl-statement-ipsetreferencestatement), use [IPSetForwardedIPConfig](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/aws-properties-wafv2-rulegroup-ipsetreferencestatement.html#cfn-wafv2-rulegroup-ipsetreferencestatement-ipsetforwardedipconfig) instead. 

Amazon WAF only evaluates the first IP address found in the specified HTTP header. 

## Syntax
<a name="aws-properties-wafv2-webacl-forwardedipconfiguration-syntax"></a>

To declare this entity in your Amazon CloudFormation template, use the following syntax:

### JSON
<a name="aws-properties-wafv2-webacl-forwardedipconfiguration-syntax.json"></a>

```
{
  "[FallbackBehavior](#cfn-wafv2-webacl-forwardedipconfiguration-fallbackbehavior)" : String,
  "[HeaderName](#cfn-wafv2-webacl-forwardedipconfiguration-headername)" : String
}
```

### YAML
<a name="aws-properties-wafv2-webacl-forwardedipconfiguration-syntax.yaml"></a>

```
  [FallbackBehavior](#cfn-wafv2-webacl-forwardedipconfiguration-fallbackbehavior): String
  [HeaderName](#cfn-wafv2-webacl-forwardedipconfiguration-headername): String
```

## Properties
<a name="aws-properties-wafv2-webacl-forwardedipconfiguration-properties"></a>

`FallbackBehavior`  <a name="cfn-wafv2-webacl-forwardedipconfiguration-fallbackbehavior"></a>
The match status to assign to the web request if the request doesn't have a valid IP address in the specified position.  
If the specified header isn't present in the request, Amazon WAF doesn't apply the rule to the web request at all.
You can specify the following fallback behaviors:  
+ `MATCH` - Treat the web request as matching the rule statement. Amazon WAF applies the rule action to the request.
+ `NO_MATCH` - Treat the web request as not matching the rule statement.
*Required*: Yes  
*Type*: String  
*Allowed values*: `MATCH | NO_MATCH`  
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`HeaderName`  <a name="cfn-wafv2-webacl-forwardedipconfiguration-headername"></a>
The name of the HTTP header to use for the IP address. For example, to use the X-Forwarded-For (XFF) header, set this to `X-Forwarded-For`.  
If the specified header isn't present in the request, Amazon WAF doesn't apply the rule to the web request at all.
*Required*: Yes  
*Type*: String  
*Pattern*: `^[a-zA-Z0-9-]+{1,255}$`  
*Update requires*: [No interruption](https://docs.amazonaws.cn/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)