Waf

Using IP Sets and Geographic Match Rules

Overview

Domain expertise for allow and block lists in AWS WAF based on source IP range or country. Covers the IP set scope that must match the web ACL, the fact that a geographic match matches only at the country level (region-level needs a paired label-match rule), the forwarded-IP configuration needed behind a proxy, and keeping a compliance country list current without hand edits.

Does not cover rate-based rules, managed rules, bot, or fraud rule groups; those are separate references. Recovering the real client IP behind a CDN has its own reference that this one points at.

Execute commands using the AWS MCP server when connected (sandboxed execution, audit logging, observability). Fall back to the AWS CLI otherwise.

Table of Contents

• Overview

• Workflow

• IP set scope must match the web ACL

• Geographic match is country-level by default

• Reading the real client IP behind a proxy

• Keeping a compliance country list current

• Troubleshooting

• Procedure

• Security Considerations

• Additional Resources

Workflow

To add IP set or geographic match rules end to end, follow the procedure exactly. See the Procedure section below.

The procedure covers:

• Creating an IP set in the scope that matches the web ACL

• Adding an IP set match or geographic match statement with an allow or block action

• Configuring forwarded-IP reading when behind a proxy

• Confirming and surfacing the console link

IP set scope must match the web ACL

An IP set used with a CloudFront web ACL must be in the Global (CloudFront) scope; a regional web ACL needs a regional IP set in the same Region. A scope mismatch means the web ACL cannot reference the IP set.

Constraints:

• You MUST create the IP set in the scope that matches the protected resource type before referencing it

• You MUST NOT expect a regional IP set to be usable from a CloudFront web ACL or vice versa

Geographic match is country-level by default

A geographic match statement matches by itself only at the country level. Region-level (sub-country) matching requires a geo match rule followed by a label-match rule. Customers try a single rule for a region and it silently does not match.

Constraints:

• You MUST pair a geo match rule with a label-match rule when the customer asks for region-level control, rather than expecting the single statement to match a sub-country region

• You SHOULD note that the geo match adds a country label automatically that the label-match rule then keys on

Reading the real client IP behind a proxy

By default a geo match reads the country from the request origin IP, which is the proxy or load balancer rather than the real client, so the wrong sources are matched.

Constraints:

• You MUST enable forwarded-IP configuration to read the client address from a header such as X-Forwarded-For when the application sits behind a proxy

• You SHOULD trust the forwarded header only from a known upstream, and pair it with the inbound-header-stripping reference (see stripping-inbound-waf-headers-before-trusting-them)

Keeping a compliance country list current

Customers maintaining a blocked-country list for compliance edit it by hand and it drifts out of date.

Constraints:

• You SHOULD point at the automated pattern that keeps the blocked-country list current from a configuration source, rather than relying on manual edits, when the list backs a compliance requirement

Troubleshooting

The web ACL cannot reference the IP set

The IP set is in the wrong scope. Recreate it in the scope that matches the web ACL (IP set scope must match the web ACL).

A region-level geo rule does not match

A single geo match statement is country-level only. Pair it with a label-match rule (Geographic match is country-level by default).

Geo matching blocks the wrong sources

The rule reads the proxy IP. Enable forwarded-IP configuration (Reading the real client IP behind a proxy).

Procedure

Overview

This procedure creates an IP set in the right scope, adds an IP set or geographic match rule, and surfaces the console link.

Parameters

• web_acl_name, web_acl_id, scope (required): Identify the web ACL.

• match_type (required): ip_set or geo.

• addresses (required for ip_set): The IP addresses and CIDR ranges.

• country_codes (required for geo): The country codes to match.

• action (required): Allow or Block.

• forwarded_ip (optional): Whether to read the client IP from a forwarding header.

Constraints for parameter acquisition:

• You MUST ask for all required parameters upfront in a single prompt

• You MUST set the IP set scope to match the web ACL before creating it

Steps

1. Verify dependencies

Constraints:

• You MUST confirm credentials with aws sts get-caller-identity

2. Create the IP set (for an IP set rule)

Constraints:

• You MUST create the IP set in the matching scope:

  Copy

  aws wafv2 create-ip-set --name {name} --scope {scope} --ip-address-version IPV4 \
    --addresses {addresses} --region {region}

• You MUST treat update-ip-set as a full replacement; pass the complete merged list, not just new entries

3. Add the match rule

Constraints:

• You MUST add the IP set match or geographic match statement with the chosen action, fetching the current LockToken immediately before update-web-acl and passing the full rule set

• You MUST preserve the web ACL's existing DefaultAction from the get-web-acl response and pass it back as {default_action}; do not assume Allow={}, since that would silently open all unmatched traffic on a web ACL whose default action is Block

• You MUST add a paired label-match rule for region-level geo control

• You MUST enable forwarded-IP configuration when the application is behind a proxy

4. Confirm and surface the console link

Constraints:

• You MUST present the web ACL console link and tell the customer to open it and confirm the rule:

  Copy

  https://us-east-1.console.aws.amazon.com/wafv2/homev2/web-acls?region={region}

Example

Example input

{
  "web_acl_name": "example-webacl",
  "web_acl_id": "abc",
  "scope": "REGIONAL",
  "match_type": "geo",
  "country_codes": ["KP", "IR"],
  "action": "Block",
  "forwarded_ip": true
}

Example output

Added a geo-match Block rule for KP, IR, reading the client IP from X-Forwarded-For.
Open the web ACL and confirm the rule:
https://us-east-1.console.aws.amazon.com/wafv2/homev2/web-acls?region=us-east-1

Troubleshooting

The IP set cannot be referenced

Scope mismatch. Recreate the IP set in the web ACL's scope (Step 2).

A sub-country region does not match

Geo match is country-level. Add a label-match rule (Step 3).

Security Considerations

This procedure modifies a security control, so misconfiguration directly weakens the application's defenses.

• Least-privilege IAM. You MUST grant only the specific wafv2: actions a task needs (for example wafv2:GetWebACL and wafv2:UpdateWebACL) rather than wafv2:* or the AWSWAFFullAccess managed policy.

• Ephemeral credentials. You MUST use IAM roles with temporary credentials (such as an EC2 instance profile, SSO session, or aws sts assume-role) rather than long-lived IAM user access keys when running these WAF CLI commands.

• Monitor configuration changes. You SHOULD enable AWS CloudTrail on wafv2 management events and set CloudWatch alarms on critical web ACL configuration changes (such as DeleteWebACL and UpdateWebACL rule removals) and on the web ACL's BlockedRequests and CountedRequests metrics, so rule changes and sudden spikes in blocked or counted traffic are detected.

• Header-spoofing risk. Any x-amzn-waf-* signal forwarded to the origin can be forged inbound. You MUST add the inbound-header-stripping rule whenever a signal or client IP is forwarded (see stripping-inbound-waf-headers-before-trusting-them); without it the origin trusts a spoofable value.

Additional Resources

• Creating and managing an IP set in AWS WAF (AWS WAF Developer Guide)

• Geographic match rule statement (AWS WAF Developer Guide)

• How to use AWS WAF to filter incoming traffic from embargoed countries (AWS Security Blog)