ReverseProxy | Simple C # reverse proxy | Proxy library

I have run in to this issue twice.

The first time was with a reverse proxy that lived inside an IPv6 only server network. Client requests come in through NAT46. The source-IP of the request becomes [fixed 96-bit prefix] + [32-bit client IPv4 address]. This means that the reverse proxy could always identify the real client IP. I couldn't find a way to set the X-Forwarded-For header to that address though. I got around it by modifying the backend server.

This time I have a reverse proxy which will run on Google App Engine. Requests hit Google's load balancer first, which adds the X-Forwarded-For header and forwards the request to my app. I want to modify the request a bit and then pass it to a backend server, which I cannot modify. The back-end needs the original client IP, and can accept it via X-Forwarded-For (it's authenticated, don't worry). In this case I want to pass the X-Forwarded-For header from Google's load balencer through unmodified.

It seems like there is no way to set X-Forwarded-For to a value that I chose when using httputil.ReverseProxy. If I set it (option 1 below) the client address from the TCP connection will be appended. If if I set it to nil (option 2 below), it is omitted like the documentation suggests, but that's not what I want either.

When messing around with Go's http/httputil.ReverseProxy, listening on a local address with a zone, making a request through it locally, including the zone, I've seen that the zone identifier ends up in the X-Forwarded-For header added by the reverse proxy. (You can see it occur around here. SplitHostPort leaves the zone intact.)

Should the zone be in the XFF IP? Does it make sense? Is it a bug?

My not-very-clear understanding of zone identifiers is that it doesn't make sense outside of the particular machine that's using it. On the other hand, maybe if you're trying to trace the path a request took, the zone is necessary to disambiguate?

I am wondering if it would be possible to cancel a web request or send an internal response to the client inside the ReverseProxy.Director function.

Suppose we do something that throws an error, or we have other reason to not forward the request.

updated:

To reproduce the issue is very simple with a few steps:

1. Install it on your Ubuntu server by running the following command:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/posthog/posthog/HEAD/bin/deploy-hobby)"

1. During the auto installation process, you will be prompted to enter the domain for your Posthog site, so enter one and wait for the process to finish.

2. Visit the domain you entered and it is accessbile.

3. Now reboot your VPS and visit the domain again it is down forever. Not accessbile even if you use your vps ip address.

I've tried this auto-installation and reboot thing three times on the same vps and ended up with the same result. I've also tried it on another vps by a new hosting provider, yet still the same issue. Fresh installation and the site will be down right after your reboot your vps!

The following is the error log I got from the Caddy container, which is generated after the vps reboot:

{"level":"error","ts":1642534398.9394724,"logger":"http.log.error","msg":"dial tcp 172.18.0.4:8000: connect: connection refused","request":{"remote_addr":"67.198.228.123:35424","proto":"HTTP/2.0","method":"GET","host":"","uri":"/preflight","headers":{"Sec-Ch-Ua":["" Not A;Brand";v="99", "Chromium";v="96", "Google Chrome";v="96""],"User-Agent":["Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36"],"Sec-Fetch-Site":["cross-site"],"Accept-Language":["en-US,en;q=0.9"],"Accept-Encoding":["gzip, deflate, br"],"Cookie":["phtoolbar=yes; csrftoken=gsVfpdF56rbYgQQdwywH45zi83i386oe5KZZef3mIE00bumaQCG3i4OM35bdJIxQ; ph_sTMFPsFhdP1Ssg_posthog=%7B%22distinct_id%22%3A%22FpLgrw74q9qcclLSJ1bOrzsiPJmZtHdKswxemTFy9LG%22%7D"],"Cache-Control":["max-age=0"],"Sec-Ch-Ua-Mobile":["?0"],"Upgrade-Insecure-Requests":["1"],"Sec-Fetch-Dest":["document"],"Sec-Ch-Ua-Platform":[""macOS""],"Accept":["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3;q=0.9"],"Sec-Fetch-Mode":["navigate"],"Sec-Fetch-User":["?1"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","proto_mutual":true,"server_name":""}},"duration":0.008754516,"status":502,"err_id":"gicbjv2m4","err_trace":"reverseproxy.statusError (reverseproxy.go:886)"} {"level":"error","ts":1642534401.5881941,"logger":"http.log.error","msg":"dial tcp 172.18.0.4:8000: connect: connection refused","request":{"remote_addr":"67.198.228.123:35424","proto":"HTTP/2.0","method":"GET","host":"","uri":"/preflight","headers":{"Cache-Control":["max-age=0"],"Sec-Ch-Ua-Mobile":["?0"],"Sec-Ch-Ua-Platform":[""macOS""],"Sec-Fetch-User":["?1"],"User-Agent":["Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36"],"Sec-Ch-Ua":["" Not A;Brand";v="99", "Chromium";v="96", "Google Chrome";v="96""],"Sec-Fetch-Mode":["navigate"],"Accept-Encoding":["gzip, deflate, br"],"Upgrade-Insecure-Requests":["1"],"Accept":["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3;q=0.9"],"Sec-Fetch-Site":["cross-site"],"Sec-Fetch-Dest":["document"],"Accept-Language":["en-US,en;q=0.9"],"Cookie":["phtoolbar=yes; csrftoken=gsVfpdF56rbYgQQdwywH45zi83i386oe5KZZef3mIE00bumaQCG3i4OM35bdJIxQ; ph_sTMFPsFhdP1Ssg_posthog=%7B%22distinct_id%22%3A%22FpLgrw74q9qcclLSJ1bOrzsiPJmZtHdKswxemTFy9LG%22%7D"]},"tls":{"resumed":false,"version":772,"cipher_suite":4865,"proto":"h2","proto_mutual":true,"server_name":""}},"duration":0.001907749,"status":502,"err_id":"27e15xwsj","err_trace":"reverseproxy.statusError (reverseproxy.go:886)"}

By the way, this is their documentaion page FYI: https://posthog.com/docs/self-host/deploy/hobby

Original question:

I've installed Posthog with their so-called hobby installation script on my vps and at first it was working fine. But right after I rebooted ubuntu and visited my self-hosted posthog site again, it would not load and just showed a blank page. It seems that something went wrong after I rebooted my vps. I've checked all the services required by Posthog with the command docker ps, and everything is up and running(check the screenshot attached).

I've been trying to figure it out for 4 days yet with no luck. I am new to docker and kubernetes so I do not know what causes the problem and what I should do. Please shed some light on this and help me :(

I am building a web application with ASP.NET Core 6.
I have:

1. Frontend.Client - a Blazor WebAssembly with the UI
2. Frontend.Server - ASP.NET Core, hosting the Blazor WebAssembly
3. Web Api - a remote REST Service
4. gRpc Service - a remote gRpc Service
5. Identity Provider - a Duende project using Duende.Bff.Yarp

My Frontend.Client is configured to call its own BFF (the Frontend.Server), while the server forwards the calls to the REST and gRpc services using Duende.Bff.YARP.
The calls to the REST service work as expected: the client passes the token automatically as by documentation.
My problem is with the calls to gRpc, which don't seem to use the correct HttpClient with the AntiForgeryToken and the Access Token as it should.
I know I'm missing some setting somewhere but I can't find any example on how to use Duende with a gRpcWebClient.

My Frontend.Client configuration contains:

I am trying to use Yarp in my gateway app for routing my applications. However as soon as it's started, I get "Route '0' requires Hosts or Path specified. Set the Path to '/{**catchall}' to match all requests."

Here is my AppSettings file:

I have a reverse proxy server using Vert.x Web Proxy, implemented with pretty standard code:

I'm implementing a simple reverse proxy in Python3 and I need to send a response with transfer-encoding chunked mode.

I've taken my cues from this post but I have some problems when sending the chunks in the format described here

If I send chunks of length <= 9 bytes the message is received correctly by the client, otherwise when sending chunks of length >= 10 bytes, it seems that some of them are not received and the message remains stuck in the client waiting indefinitely

Here is an example of non working code:

After deploying to AWS EKS I get this error

Gtihub repo: https://github.com/oussamabouchikhi/udagram-microservices

Steps to reproduce

1. Create AWS EKS cluster and node groups
2. Configure EKS cluster with kubectl
3. Deploy to EKS cluster (secrets first, then other services, then reverserproxy)
   . kubectl apply -f env-secret.yaml
   . kubectl apply -f aws-secret.yaml
   . kubectl apply -f env-configmap.yaml
   . ...
   . kubectl apply -f reverseproxy-deployment.yaml
   . kubectl apply -f reverseproxy-service.yaml

nginx-config