Caddy & CrowdSec: Fixing 403 Errors & Ban Page Issues

Hey there! If you're wrestling with CrowdSec and Caddy and scratching your head over inconsistent ban page displays and pesky 403 errors, you're in the right place. It's frustrating when some sites show the friendly CrowdSec ban page while others just give you a cold, impersonal 403. Let's dive in and unravel this mystery, helping you get your Caddy setup running smoothly with CrowdSec.

Understanding the Core Issue: Inconsistent Ban Behavior

The heart of the problem seems to be the inconsistent behavior you're observing. You've correctly identified that some sites correctly display the CrowdSec ban page when you trigger a ban (like manually banning yourself for testing), while others stubbornly throw a 403 error. This inconsistency can stem from a few different factors, mainly the order and configuration of your Caddyfile directives. Let's break down the likely culprits and how to address them.

The Role of order crowdsec first

Your use of order crowdsec first is a great starting point. This directive ensures that CrowdSec's checks happen before other handlers. This is essential because it allows CrowdSec to intercept and handle requests before they reach other parts of your configuration. Without this, a 403 might be served by another handler before CrowdSec has a chance to intervene.

Analyzing Your Caddyfile Configuration

Let's meticulously examine your Caddyfile, line by line, to see where the inconsistencies might be arising. Your setup has several key components: the (private-ips) snippet, the (private-app) snippet, and the site-specific configurations for jellyseerr.domain.com and radarr.domain.com. Each of these plays a role in how CrowdSec interacts with incoming requests.

(private-ips) {
        client_ip 192.168.1.0/24 192.168.2.0/24 192.168.39.3/32 192.168.100.0/24
}
(private-app) {
        @private {
                import private-ips
        }
        handle /caddy-security/* {
                authenticate with myportal
        }
        handle @private {
                crowdsec
                authorize with mypolicy
                reverse_proxy {args[0]}
        }
        handle {
                respond "Access denied" 403
        }
}
jellyseerr.domain.com {
        crowdsec
        handle {
                reverse_proxy 192.168.40.131:5055
        }
}
radarr.domain.com {
        import private-app 192.168.40.158:7878
}

Key Areas for Troubleshooting

• Ordering of Handlers: The order in which handlers are defined is crucial. crowdsec must be placed before any other handler that might prematurely respond with a 403.
• Scope of CrowdSec: Ensure that CrowdSec is correctly applied to the relevant routes. For instance, in jellyseerr.domain.com, crowdsec is directly applied at the top level, which is correct. The radarr.domain.com setup leverages the private-app snippet, which also includes CrowdSec. This should, in principle, ensure CrowdSec protection for both domains.
• Specificity of Routes: Pay close attention to how you're defining your routes and the order in which they're evaluated. If a more specific route (like /caddy-security/*) is evaluated before the general CrowdSec handler, it could interfere.

Deep Dive: Pinpointing the Root Cause of 403 Errors

Let's delve deeper into potential causes of the 403 errors and how to remedy them.

Handler Execution Order Matters

• Caddy's Processing Logic: Caddy processes the directives in your Caddyfile sequentially. It starts at the top and works its way down. When a request comes in, Caddy checks each directive until it finds a match. Once a match is found, Caddy usually executes the handlers associated with that match. It's the usually that matters here.
• The handle Directive: The handle directive is a crucial part of this process. It tells Caddy to execute the enclosed directives if the request matches the specified criteria (e.g., a specific path or a named matcher like @private).
• The respond Directive: The respond directive is a quick way to send a response. If a respond directive with a 403 status is encountered before CrowdSec has a chance to act, you'll get a 403 error, bypassing the CrowdSec ban page.

Analyzing the private-app Snippet

The private-app snippet is interesting. It uses a named matcher @private based on the import private-ips. This setup suggests that any request matching an IP address in private-ips will be considered "private". Let's consider the flow:

1. Request Arrives: A request hits radarr.domain.com (which imports private-app).
2. IP Check: The request's IP address is checked against private-ips.
3. Authentication (if applicable): If the IP matches, the request then proceeds to authenticate with myportal (in the /caddy-security/* handle).
4. CrowdSec and Authorization: If authenticated, the request then goes to crowdsec, and if all checks pass, it authorizes with mypolicy and then proxies to 192.168.40.158:7878.
5. The Catch-All handle: If none of the above matches succeed, the final handle (which just returns a 403) is triggered.

In this setup, the 403 will only be returned if the request doesn't match any of the above conditions. Make sure your IP is within the range defined in private-ips to avoid unexpected 403s.

Jellyseerr and the Direct crowdsec Directive

In contrast to the radarr.domain.com setup, jellyseerr.domain.com directly applies crowdsec at the top level, followed by a reverse_proxy. This is a straightforward approach. When a request hits jellyseerr.domain.com, CrowdSec will first check the request. If the request is banned, CrowdSec should serve its ban page. If the request is not banned, the reverse_proxy will forward the request. The 403 error is less likely here unless there is an issue with the CrowdSec module itself or it’s not properly configured.

Troubleshooting Steps: A Practical Guide

Here’s a structured approach to troubleshoot the 403 errors and inconsistent ban page behavior.

1. Verification of CrowdSec Configuration

• Ensure CrowdSec is Running: Confirm that the CrowdSec service itself is running correctly and receiving signals from your Caddy instance. Check CrowdSec logs for any errors related to your Caddy configuration.
• Check the CrowdSec Bouncer: Verify the CrowdSec Caddy bouncer is properly configured to communicate with your CrowdSec instance. This is typically done in the Caddyfile with the crowdsec directive. Make sure the API key and other settings are accurate.
• Inspect CrowdSec Logs: Review the logs from both Caddy and CrowdSec to understand whether bans are being triggered and why. Look for specific IP addresses and the decisions being made by CrowdSec.

2. Caddyfile Refinement

• Double-Check the Order: Ensure order crowdsec first is correctly placed in your global block. This is paramount for CrowdSec to act before other handlers.
• Simplify and Test: Temporarily simplify your configuration for testing purposes. For example, comment out the authenticate directive in private-app to eliminate any authentication conflicts. Test after each change to isolate the issue.
• Direct CrowdSec Application: For troubleshooting, consider applying crowdsec directly to all your site blocks to see if the issue persists. This will help you isolate if the problem is specific to how you’re importing configurations.

3. Log Analysis & Debugging

• Caddy Logs: Enable more verbose logging in Caddy (e.g., debug) to capture detailed information about request processing. This can help you identify which handlers are being triggered and in what order.
• Request Tracing: Use a tool like curl with the -v (verbose) option to see the full HTTP request and response headers. This can reveal which headers are being set and where the 403 errors are originating.
• CrowdSec Debugging Mode: Enable debugging mode in CrowdSec to see what decisions it's making based on your configuration and the incoming requests. This will help you know if CrowdSec is working as expected.

4. Restart vs. Reload

You mentioned that restarting Caddy sometimes fixes the issue. Caddy supports graceful reloads, which usually suffice for configuration changes. However, if the behavior is only fixed by a full restart, it might indicate a more fundamental issue, such as a problem with the CrowdSec module itself or some internal state that is not correctly reset during a reload. Try to restart the CrowdSec service after reloading your Caddy configuration. This can ensure both services are in sync.

Advanced Troubleshooting: Edge Cases and Advanced Configurations

• IP Spoofing and Proxy Issues: If you're behind a proxy or load balancer, ensure that Caddy is correctly identifying the client's IP address. This might involve configuring the X-Forwarded-For header or other proxy-specific settings.
• Custom Ban Pages: If you're using custom ban pages, make sure they are correctly configured and accessible by the Caddy server. Incorrect paths or permissions could lead to errors.
• Rate Limiting and Flood Protection: While CrowdSec handles bans, also ensure that rate-limiting and flood protection are not inadvertently interfering with the ban behavior. These could, in some configurations, preempt CrowdSec's actions.

Conclusion: Achieving Consistent CrowdSec Ban Pages

By meticulously reviewing your Caddyfile, verifying the order of your handlers, and carefully analyzing logs, you can pinpoint the source of the inconsistent behavior. Remember to test thoroughly after each change, and don't hesitate to simplify your configuration for troubleshooting. With these steps, you should be able to achieve the desired result: consistent display of the CrowdSec ban page and robust protection for your web applications.

For further reading and support, check out the official CrowdSec documentation and Caddy documentation. These resources offer a wealth of information and troubleshooting tips.

External Link:

• CrowdSec Documentation - The official CrowdSec documentation is an essential resource for understanding how CrowdSec works and configuring it. This should be your first port of call when troubleshooting any CrowdSec-related issues.