Firewall Blocking and Whitelisting: Troubleshooting Access Issues
If IP and User-Agent whitelisting has been applied but access is still blocked, check whether another security layer is sitting in front of the site.
Traffic may still be stopped by an upstream WAF, browser or JavaScript challenge, CDN rule, or separate server-level protection.
What has been done already?
The following actions can be used to isolate the issue:
- Whitelist the relevant IP addresses.
- Confirm the User-Agent being allowed is correct.
- Retest access after the whitelist changes are in place.
What if access is still blocked?
If whitelisting does not resolve the issue, review whether there are other blocking systems in place ahead of the firewall. A browser-check cookie may also be part of the access flow, so browser and session checks should be reviewed alongside IP and User-Agent rules.
Which security layers may still block traffic?
Potential layers include:
- An upstream WAF
- A browser or JavaScript challenge
- A CDN rule
- Separate server-level protection
- Browser-check cookies or session checks
What should be confirmed next?
Confirm whether there are any other systems in front of the site that could still block requests, and verify whether the same User-Agent can be allowed through any browser-check or cookie-based checks.