Force All Web Server Traffic Through CloudFlare

I would like to restrict all web traffic 80 and 443 through Cloudflare

I am able to do this by only allowing traffic outbound to their Proxy Blocks listed here:

With this in mind:
I need a way to push LetsEncrypt to validate certificates through Cloudflare OR to allow LetsEncrypt through my Firewall rules.

I have seen previous posts in which you stated you don’t want to provide a public list of IP blocks that LetsEncrypt will utilize. But I believe that we should atleast be able to get LetsEncrypt to work through an allowed method at least to provide additional layers of security.



ACME HTTP-01 validation works by making requests to your website. If you want a certificate for, Let’s Encrypt’s validation servers make requests to

It’s fine if is using Cloudflare, as long as the requests succeed.

TLS-ALPN-01 validation won’t work through Cloudflare’s web proxy.

DNS-01 validation uses DNS queries. It doesn’t make HTTP requests at all.

In other words, Cloudflare should not pose any obstacles, unless you’re using TLS-ALPN-01 validation, or set it to block everything.

If there are configuration issues, they can be fixed.

For proxied (sub)domains, you can also use Cloudflare’s Origin CA instead of Let’s Encrypt.

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you’d better use Cloudflare origin certificate for talk to cloudflare.

client’s won’t see your lets encrypt cert unless you are using at least business plan from them.

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