worker_processes	1;

events {
	worker_connections	1024;
}

http {
	default_type	application/octet-stream;

	log_format		main	'$remote_addr - $remote_user [$time_local] "$request" '
					'$status $body_bytes_sent "$http_referer" '
					'"$http_user_agent" "$http_x_forwarded_for"';

	sendfile		on;
	keepalive_timeout	65;

	server {
		listen		[::]:80 ipv6only=off default_server;
		server_name	localhost _;

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

		# You MUST set this for dual-stack setups!
		set		$client_ip_port		"$remote_addr:$remote_port";
		if ($remote_addr ~ "^.+:.+$") {
			set	$client_ip_port		"[$remote_addr]:$remote_port";
		}

		location / {
			# For UDS FastCGI (the default URI).
			# UDS FastCGI is the recommended setup, as it provides the most accuracy,
			# requires the least amount of configuration, and is the most performant.
			# Yes, Virginia, even more performant than localhost network ports.
			include		fastcgi.inc;
			fastcgi_pass	unix:/var/run/clientinfo/fcgi.sock;
			#
			# For TCP FastCGI. (See the clientinfo.env file for a corresponding URI.)
			#include		fastcgi.inc;
			#fastcgi_pass		127.0.0.1:4321;
			#
			# For HTTP. (See the clientinfo.env file for a corresponding URI.)
			# BE SURE to explicitly set (NOT add) the X-ClientInfo-RealIP header
			# if reverse-proxying, and enclose in brackets if IPv6!
			# (FastCGI via fastcgi.inc does this automatically for fastcgi_pass.)
			# Note that in dual-stack NGINX (as configured here), the $client_ip_port
			# will use IPv6-mapped IPv4 (https://www.rfc-editor.org/rfc/rfc5156.html#section-2.2)
			# for IPv4 clients, which looks like e.g. "[::ffff:<IP>]:<Port>".
			# FastCGI will use the expected "<IP>:<Port>" format for IPv4 clients.
			#proxy_set_header	X-ClientInfo-RealIP	"$client_ip_port";
			#proxy_http_version	1.1;
			#proxy_pass		http://127.0.0.1:1234;
		}

		# Alternatively, if you only wanted to return the client's IP,
		# you don't even need ClientInfo, it can be returned directly.
		# See https://nginx.org/en/docs/varindex.html
		location /ip {
			return		200	"$remote_addr";
		}
		# Likewise, ...
		location /ipport {
			return 		200	"$client_ip_port";
		}
		# And so forth.

		error_page   500 502 503 504  /50x.html;

		location = /50x.html {
			root   /usr/share/nginx/html;
		}
	}
}