1. Login to AWS Console: Go to the AWS Management Console (https://aws.amazon.com/console/) and log in to your account.
2. Navigate to EC2 Dashboard: Click on the “Services” dropdown menu at the top of the page, select “EC2” under the “Compute” section.
3. Go to Load Balancers: In the EC2 Dashboard, under the “Load Balancing” section in the navigation pane, click on “Load Balancers”.
4. Select the ALB: Select the Application Load Balancer (ALB) that you want to remediate with Desync Mitigation Mode.
5. Edit Attributes: In the description tab of the selected ALB, click on the “Attributes” tab.
6. Enable Desync Mitigation Mode: Scroll down to find the “Desync Mitigation Mode” attribute and click on the “Edit” button next to it.
7. Set Desync Mitigation Mode: In the dropdown menu that appears, select the appropriate option for Desync Mitigation Mode. You can choose between “Defensive” and “Strict” mode based on your requirements.
8. Save Changes: After selecting the desired Desync Mitigation Mode, click on the “Save” button to apply the changes.
9. Review Configuration: Verify that the Desync Mitigation Mode has been successfully set for the ALB by checking the attribute settings.
10. Test the ALB: It is recommended to perform thorough testing of your ALB after making configuration changes to ensure that the Desync Mitigation Mode is functioning as expected.

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1. Open your terminal and ensure that you have the AWS CLI installed and configured with the necessary permissions to modify Elastic Load Balancers.
2. Run the following AWS CLI command to enable Desync Mitigation Mode for your Application Load Balancer (ALB):

aws elbv2 modify-load-balancer-attributes --load-balancer-arn <YOUR_ALB_ARN> --attributes Key=deletion_protection.enabled,Value=true Key=desync-mitigation-mode.enabled,Value=true

3. Verify that the Desync Mitigation Mode has been successfully enabled by describing the load balancer attributes using the following AWS CLI command:

aws elbv2 describe-load-balancer-attributes --load-balancer-arn <YOUR_ALB_ARN>

1. Install Boto3: Ensure you have Boto3 installed in your Python environment. You can install it using pip:

pip install boto3

2. Configure AWS Credentials: Make sure you have configured AWS credentials with the necessary permissions to update the ALB settings. You can do this by setting up the AWS CLI or by setting environment variables with access key and secret key.
3. Write Python Script: Create a Python script with the following code to update the ALB settings with Desync Mitigation Mode enabled:

import boto3

# Define the ALB ARN and Desync Mitigation Mode
alb_arn = 'YOUR_ALB_ARN'
desync_mode = 'monitor'  # Options: monitor | defensive | strict

# Create a Boto3 client for Elastic Load Balancing
elbv2_client = boto3.client('elbv2')

# Update the ALB settings with Desync Mitigation Mode
response = elbv2_client.modify_load_balancer_attributes(
    LoadBalancerArn=alb_arn,
    Attributes=[
        {
            'Key': 'routing.http.desyncmitigationmode',
            'Value': desync_mode
        },
    ]
)

print("ALB Desync Mitigation Mode set to:", desync_mode)

4. Replace ‘YOUR_ALB_ARN’ with the actual ARN of your ALB. You can find the ARN of your ALB in the AWS Management Console or by using the describe_load_balancers() method in Boto3.
5. Run the Script: Save the Python script and run it using Python. This will update the ALB settings with the Desync Mitigation Mode enabled.