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Cloudflare Developers•4mo ago

Getting error 521 stating web server is down; it's definitely not.

If I edit my hosts file to point to my server's IP address when I type the hostname, it loads just fine. Worked for about an hour earlier when I first enabled CloudFlare, before ceasing to work and giving that error. I am using a Docker application that runs a web server on port 9000, and then a nginx reverse proxy with LetsEncrypt certificate to enable the https:// page. SSL settings in CloudFlare are set to Flexible. Can anybody assist? I just created an account and am trying to get the CDN function to work

53 Replies

drfsupercenterOP•4mo ago

If you are the owner of this website: Contact your hosting provider letting them know your web server is not responding.

lol. I am the host, it's my VPS and I configured it all myself. I am going to set it back to "DNS only" for now since it renders my site completely useless to my visitors, any help would be appreciated

Idle•4mo ago

no response is no response. your server is not responding to the cloudflare proxy.

I configured it all by myself

then you should know how to fix it as well

drfsupercenterOP•4mo ago

What port(s) does the proxy listen on? It responds to me if I turn off CloudFlare proxy. And no, I clearly don't know how to fix it or I wouldn't be asking for help. I'm just saying CloudFlare's comment about "ask your host" doesn't help because I AM the host.

Hard@Work•4mo ago

https://developers.cloudflare.com/fundamentals/reference/network-ports/#network-ports-compatible-with-cloudflares-proxy

Cloudflare Docs

Network ports · Cloudflare Fundamentals docs

Learn which network ports Cloudflare proxies by default and how to enable Cloudflare’s proxy for additional ports.

drfsupercenterOP•4mo ago

my server is using 443 let me paste the nginx reverse proxy config

Idle•4mo ago

http on port 80, https on port 443 it might help to look at logs of your reverse proxy or docker container...

drfsupercenterOP•4mo ago

hm

Idle•4mo ago

or run a trace from your cloudflare dashboard

drfsupercenterOP•4mo ago

wait, how do I do that I'm literally new to this whole thing, just signed up yesterday the HTTP is running on port 9000, not 80. But the reverse proxy makes it HTTPS on 443 which should be fine?

Idle•4mo ago

No description

Idle•4mo ago

this is ok if your server responds to https traffic

drfsupercenterOP•4mo ago

yes that's why I'm confused at the 521 error like it works fine if I turn the proxy off and use it as straight DNS

Idle•4mo ago

time to start debugging make sure you are not being served a cached response

drfsupercenterOP•4mo ago

🤔

server {
         listen 88;
         server_name   scanner.drfsupercenter.info;
         location / {
                proxy_pass              http://127.0.0.1:9000/;
                proxy_set_header        Host $host;
                proxy_set_header        X-Real-IP $remote_addr;
                proxy_request_buffering off;
                proxy_buffering         off;
                proxy_set_header        Connection keep-alive;
        }

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/scanner.drfsupercenter.info/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/scanner.drfsupercenter.info/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot







}

server {
         listen 88;
         server_name   scanner.drfsupercenter.info;
         location / {
                proxy_pass              http://127.0.0.1:9000/;
                proxy_set_header        Host $host;
                proxy_set_header        X-Real-IP $remote_addr;
                proxy_request_buffering off;
                proxy_buffering         off;
                proxy_set_header        Connection keep-alive;
        }

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/scanner.drfsupercenter.info/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/scanner.drfsupercenter.info/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot







}

So here is my nginx config No idea why that says 88, it works on 443 but it's literally just doing proxy_pass from 9000

drfsupercenterOP•4mo ago

No description

drfsupercenterOP•4mo ago

nginx access logs not showing anything past 10:31 🤔 rebooting it so it forces it to make new logfiles Yeah uh, there's nothing in the nginx access log at all once I turn the cloudflare proxy on It's like cloudflare isn't even trying. If I bypass DNS, page loads just fine and I see my requests in the log. you guys got any ideas @Hard@Work | R2 @Idle ? The web server is totally responsive on 443, like I said if I use my hostsfile to bypass DNS it loads just fine. But somehow CloudFlare is just not trying at all, it gives the error 521 and doesn't even attempt to load any content from the page, hence nothing showing up in the access logs

Idle•4mo ago

what's your hosting provider

drfsupercenterOP•4mo ago

Contabo It's a VPS, running Debian 12 yeah this is so weird https://scanner.drfsupercenter.info/static/favicons/navbar.png

Idle•4mo ago

what does your cloudflare trace look like

drfsupercenterOP•4mo ago

this is just a picture works fine if I bypass proxy

Idle•4mo ago

check the ray id

drfsupercenterOP•4mo ago

???? how

Idle•4mo ago

go to security

drfsupercenterOP•4mo ago

all I saw was this btw

No description

drfsupercenterOP•4mo ago

tells me nothing

Idle•4mo ago

events search by Ray id

Idle•4mo ago

No description

drfsupercenterOP•4mo ago

all I see is the blocks

No description

drfsupercenterOP•4mo ago

I set it to block people not in the US

Idle•4mo ago

💀 look at the service header as well every block is from a custom rule Maybe check those...

drfsupercenterOP•4mo ago

where is that? I turned my rules off just to make sure it's not an issue, but I still get the 521 🦗 is 172.58.120.13 one of the CloudFlare proxy IPs?

172.58.120.13 - - [18/Jul/2024:12:10:09 -0400] "POST /api/get_data HTTP/1.1" 200

172.58.120.13 - - [18/Jul/2024:12:10:09 -0400] "POST /api/get_data HTTP/1.1" 200

I see a bunch of these in the nginx logs

Hard@Work•4mo ago

Nope:

No description

drfsupercenterOP•4mo ago

How the frick is somebody getting my site to load???? I still get the 521 cloudflare page. Do you have any ideas? This is bugging me and I'm close to just turning proxy off and abandoning the whole thing If there's an issue with my nginx config, lmk and I'll fix it

Hard@Work•4mo ago

What if you disable SSL on your origin?

drfsupercenterOP•4mo ago

hmm ok, so it proxies to port 88 (HTTP) and 443 (HTTPS). If I turn CloudFlare proxy off, both work. If I turn CloudFlare proxy on, the :88 doesn't work if I set SSL/TLS to "flexible" I don't think it works when I turn it off either, it just says "error too many redirects" are you saying I should do port 80 binding? actually I might try that, hold on I can't figure out how to make it not auto redirect to HTTPS 😐 hey ok, so I finally figured out how to disable SSL. Bad news, still isn't working. When I use hostfile trick, works just fine using http:// but on every other machine it still tries to redirect to https:// and then gives a browser error for "too many redirects"

drfsupercenterOP•4mo ago

I don't even get why...

No description

drfsupercenterOP•4mo ago

Tried on a different IP, it's not redirecting to https but still gives ERR_TOO_MANY_REDIRECTS OH! I think I figured it out. Flexible "Enable encryption only between your visitors and Cloudflare. This avoids browser security warnings, but all connections between Cloudflare and your origin are made through HTTP." Since the origin server wasn't doing HTTP, and only HTTPS, that explains it

Hard@Work•4mo ago

Yeah, I meant leave Cloudflare on Flexible, but completely remove SSL from your origin

drfsupercenterOP•4mo ago

Yeah, I got it Do you know how I can make other ports work? With CloudFlare proxy on, only 80 and 443 work, if I try to load my-domain:9001 for example it doesn't load.

Hard@Work•4mo ago

https://developers.cloudflare.com/fundamentals/reference/network-ports/#how-to-enable-cloudflares-proxy-for-additional-ports

Cloudflare Docs

Network ports · Cloudflare Fundamentals docs

Learn which network ports Cloudflare proxies by default and how to enable Cloudflare’s proxy for additional ports.

drfsupercenterOP•4mo ago

Configure a Spectrum application for the hostname running the server. Spectrum supports all ports. Spectrum for all TCP and UDP ports is only available on the Enterprise plan. If you would like to know more about Cloudflare plans, please reach out to your Cloudflare account team.

so basically no? I'm not paying for enterprise I don't get why it can't just "grey cloud" stuff outside the standard ports

Hard@Work•4mo ago

Because you either use Cloudflare for everything on a given subdomain, or you use it for nothing You can't tell a client to use Cloudflare for these ports, and your server for these other ports

drfsupercenterOP•4mo ago

I get that, but why can't it just point straight to my server (bypassing the cloud cache) for ports it doesn't support? Instead of just blocking traffic

Hard@Work•4mo ago

Because the IPs that Cloudflare uses to serve your traffic are shared by many other customers. You can sort which customer should receive which request with HTTP, but you can't do that with arbitrary TCP/UDP services Which means you need to dedicate an IP to each customer that wants this service(which is what Spectrum does)

drfsupercenterOP•4mo ago

what? I thought the whole point of CloudFlare was to cache content on multiple servers. You should be able to bypass it and just connect directly to the host server, like what I did by modifying the hosts file

Hard@Work•4mo ago

You can selectively bypass the cache, but you can't selectively bypass the proxy. This is the same as with nginx

drfsupercenterOP•4mo ago

ok but with nginx you can just tell it to listen on more ports...

Hello, I’m Allie!•4mo ago

Yes, but if 2k customers all share the same IP address, and I receive a connection on port 9000, how do I know how to route it to your server?

drfsupercenterOP•4mo ago

the same way it knows to load assets directly from my server when they aren't cached 🤔

Idle•4mo ago

🍎 == :orange: ?

Upioti•4mo ago

You can do SRV records to redirect all ports used to another subdomain Is what you normally do on mc to run the website protected but have joinable mc server without spectrum

drfsupercenterOP•4mo ago

mc?

Idle•4mo ago

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