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pepito's avatar
pepito
Icon for Altocumulus rankAltocumulus
Oct 28, 2022

How to tell nginx to use a forward proxy to reach a specific destination

Hello. I accidentally closed my previous post, so I recreate this discussion because of the following problem I'm encountering. Here is the situation : I have multiple servers which are in a secu...
application delivery
devops
security
  • Kevin_Davies's avatar
    Kevin_Davies
    Nov 09, 2022

    Seems I have also made a mistake. In setting a proxy setting for git it treats the NGINX as a forward proxy. The issue with this is NGINX is a reverse proxy. In effect it acts as an endpoint for the forward proxy you are trying to reach.

    The error is due to NGINX  trying to interpret a forward proxy request. So I figure we need to tell it to not do any processing on the traffic and we do that with the stream command which passes the TCP stream directly to the destination.

    stream {
    upstream web_server {
        # Our web server, listening for SSL traffic
        # Note the web server will expect traffic
        # at this xip.io "domain", just for our
        # example here
        server PROXYIP:PROXYPORT;
    }

    server {
        listen 443;
        proxy_pass web_server;
    }
}

    The issue with this is it intercepts ALL traffic on 443. If you dont want that then have it listen on a different port and adjust the .gitconfig to specify its proxy on the new port. You cannot tell it to match a name because at the TCP layer there is no server name. 


pepito's avatar
pepito
Icon for Altocumulus rankAltocumulus

Hello !

Thank you for your answer.

Here is NGINX configuration :

 

server {
  listen 443 ssl;
  server_name <GITLAB-HOST>;

  ssl_certificate /etc/nginx/certs/mycert.crt;
  ssl_certificate_key /etc/nginx/certs/mykey.key;
  ssl_session_cache shared:SSL:1m;
  ssl_prefer_server_ciphers   on;

  access_log /var/log/nginx/access.log;
  error_log  /var/log/nginx/error.log debug;

  location / {
    proxy_set_header Host $http_host;
    proxy_connect_timeout 60;
    proxy_read_timeout 60;
    proxy_send_timeout 60;
    proxy_intercept_errors off;
    proxy_http_version 1.1;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_pass https://<PROXY-IP>:<PROXY-PORT>;
  }
}

 

 

And here is the .gitconfig file from a client :

 

[http]
        sslCAInfo = <path-to-truststore>
[http "https://<GITLAB-HOST>"]
        proxy = https://<NGINX-HOST-IP>:443
        sslCAInfo = <path-to-truststore>

 

 

Here is the git command that I perform on the client and the result :

 

git clone https://<LOGIN>@<GITLAB-HOST>/myrepo.git
Cloning into 'myrepo'...
fatal: unable to access 'https://<GITLAB-HOST>/myrepo.git/': Failed connect to <GITLAB-HOST>:443; Connection timed out

 

 

Here is the version of git CLI on the client :

 

git-1.8.3.1-23.el7_8.x86_64

 

 

And my version of NGINX on the nginx host :

 

# nginx -v
nginx version: nginx/1.20.2

 

 

I tried something else in my ~/.gitconfig file. I kept only one http section :

 

[http]
  sslCAInfo = <truststore-path>
  proxy = https://<NGINX-HOST-IP>:443

 

But now, I have a 400 http error when I execute the git command :

 

git clone https://<LOGIN>@<GITLAB-HOST>/myrepo.git
Cloning into 'myrepo'...
fatal: unable to access 'https://<GITLAB-HOST>/myrepo.git/': Received HTTP code 400 from proxy after CONNECT

 

And I can see this in NGINX logs :

 

2022/11/08 10:25:09 [info] 24032#24032: *1 client sent invalid request while reading client request line, client: <CLIENT-IP>, server: <GITLAB-HOST>, request: "CONNECT <GITLAB-HOST>:443 HTTP/1.1"

 

Thank you in advance !

Kevin_Davies's avatar
Kevin_Davies
Icon for MVP rankMVP
Nov 09, 2022

Seems I have also made a mistake. In setting a proxy setting for git it treats the NGINX as a forward proxy. The issue with this is NGINX is a reverse proxy. In effect it acts as an endpoint for the forward proxy you are trying to reach.

The error is due to NGINX  trying to interpret a forward proxy request. So I figure we need to tell it to not do any processing on the traffic and we do that with the stream command which passes the TCP stream directly to the destination.

stream {
    upstream web_server {
        # Our web server, listening for SSL traffic
        # Note the web server will expect traffic
        # at this xip.io "domain", just for our
        # example here
        server PROXYIP:PROXYPORT;
    }

    server {
        listen 443;
        proxy_pass web_server;
    }
}

The issue with this is it intercepts ALL traffic on 443. If you dont want that then have it listen on a different port and adjust the .gitconfig to specify its proxy on the new port. You cannot tell it to match a name because at the TCP layer there is no server name. 


  • pepito's avatar
    pepito
    Icon for Altocumulus rankAltocumulus
    Nov 10, 2022

    Hello Kevin.

    I tried your solution and it works fine, thanks for your help !

    Best regards.