# Using reverse proxy for Short.io custom domains

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Short.io provides a scalable infrastructure, which involves multiple IP addresses from around the world to serve your customers in a fastest way.

While we don't support running Short.io on customers' infrastructure, you can setup a simple reverse proxy between your clients and Short.io.

You need to install nginx and apply this configuration to it:

```
# Generated by nginxconfig.io
# https://www.digitalocean.com/community/tools/nginx?domains.0.server.redirectSubdomains=false&domains.0.https.http2=false&domains.0.https.forceHttps=false&domains.0.https.hsts=false&domains.0.https.certType=custom&domains.0.php.php=false&domains.0.reverseProxy.reverseProxy=true&domains.0.reverseProxy.proxyPass=http%3A%2F%2Fcname.short.io&domains.0.routing.root=false&global.tools.modularizedStructure=false

user                 www-data;
pid                  /run/nginx.pid;
worker_processes     auto;
worker_rlimit_nofile 65535;

# Load modules
include              /etc/nginx/modules-enabled/*.conf;

events {
    multi_accept       on;
    worker_connections 65535;
}

http {
    charset                utf-8;
    sendfile               on;
    tcp_nopush             on;
    tcp_nodelay            on;
    server_tokens          off;
    log_not_found          off;
    types_hash_max_size    2048;
    types_hash_bucket_size 64;
    client_max_body_size   16M;

    # MIME
    include                mime.types;
    default_type           application/octet-stream;

    # Logging
    access_log             /var/log/nginx/access.log;
    error_log              /var/log/nginx/error.log warn;

    # SSL
    ssl_session_timeout    1d;
    ssl_session_cache      shared:SSL:10m;
    ssl_session_tickets    off;

    # Diffie-Hellman parameter for DHE ciphersuites
    ssl_dhparam            /etc/nginx/dhparam.pem;

    # Mozilla Intermediate configuration
    ssl_protocols          TLSv1.2 TLSv1.3;
    ssl_ciphers            ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;

    # OCSP Stapling
    ssl_stapling           on;
    ssl_stapling_verify    on;
    resolver               1.1.1.1 1.0.0.1 8.8.8.8 8.8.4.4 208.67.222.222 208.67.220.220 valid=60s;
    resolver_timeout       2s;

    # Connection header for WebSocket reverse proxy
    map $http_upgrade $connection_upgrade {
        default upgrade;
        ""      close;
    }

    map $remote_addr $proxy_forwarded_elem {

        # IPv4 addresses can be sent as-is
        ~^[0-9.]+$        "for=$remote_addr";

        # IPv6 addresses need to be bracketed and quoted
        ~^[0-9A-Fa-f:.]+$ "for=\"[$remote_addr]\"";

        # Unix domain socket names cannot be represented in RFC 7239 syntax
        default           "for=unknown";
    }

    map $http_forwarded $proxy_add_forwarded {

        # If the incoming Forwarded header is syntactically valid, append to it
        "~^(,[ \\t]*)*([!#$%&'*+.^_`|~0-9A-Za-z-]+=([!#$%&'*+.^_`|~0-9A-Za-z-]+|\"([\\t \\x21\\x23-\\x5B\\x5D-\\x7E\\x80-\\xFF]|\\\\[\\t \\x21-\\x7E\\x80-\\xFF])*\"))?(;([!#$%&'*+.^_`|~0-9A-Za-z-]+=([!#$%&'*+.^_`|~0-9A-Za-z-]+|\"([\\t \\x21\\x23-\\x5B\\x5D-\\x7E\\x80-\\xFF]|\\\\[\\t \\x21-\\x7E\\x80-\\xFF])*\"))?)*([ \\t]*,([ \\t]*([!#$%&'*+.^_`|~0-9A-Za-z-]+=([!#$%&'*+.^_`|~0-9A-Za-z-]+|\"([\\t \\x21\\x23-\\x5B\\x5D-\\x7E\\x80-\\xFF]|\\\\[\\t \\x21-\\x7E\\x80-\\xFF])*\"))?(;([!#$%&'*+.^_`|~0-9A-Za-z-]+=([!#$%&'*+.^_`|~0-9A-Za-z-]+|\"([\\t \\x21\\x23-\\x5B\\x5D-\\x7E\\x80-\\xFF]|\\\\[\\t \\x21-\\x7E\\x80-\\xFF])*\"))?)*)?)*$" "$http_forwarded, $proxy_forwarded_elem";

        # Otherwise, replace it
        default "$proxy_forwarded_elem";
    }

    # Load configs
    include /etc/nginx/conf.d/*.conf;

    # example.com
    server {
        listen                             80;
        listen                             [::]:80;
        listen                             443 ssl;
        listen                             [::]:443 ssl;
        server_name                        example.com;

        # SSL
        ssl_certificate                    /etc/nginx/ssl/example.com.crt;
        ssl_certificate_key                /etc/nginx/ssl/example.com.key;

        # security headers
        add_header X-XSS-Protection        "1; mode=block" always;
        add_header X-Content-Type-Options  "nosniff" always;
        add_header Referrer-Policy         "no-referrer-when-downgrade" always;
        add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'; frame-ancestors 'self';" always;
        add_header Permissions-Policy      "interest-cohort=()" always;

        # . files
        location ~ /\.(?!well-known) {
            deny all;
        }

        # reverse proxy
        location / {
            proxy_pass                         http://cname.short.io;
            proxy_http_version                 1.1;
            proxy_cache_bypass                 $http_upgrade;

            # Proxy headers
            proxy_set_header Upgrade           $http_upgrade;
            proxy_set_header Connection        $connection_upgrade;
            proxy_set_header Host              $host;
            proxy_set_header X-Real-IP         $remote_addr;
            proxy_set_header Forwarded         $proxy_add_forwarded;
            proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-Forwarded-Host  $host;
            proxy_set_header X-Forwarded-Port  $server_port;

            # Proxy timeouts
            proxy_connect_timeout              60s;
            proxy_send_timeout                 60s;
            proxy_read_timeout                 60s;
        }

        # favicon.ico
        location = /favicon.ico {
            log_not_found off;
            access_log    off;
        }

        # robots.txt
        location = /robots.txt {
            log_not_found off;
            access_log    off;
        }

        # gzip
        gzip            on;
        gzip_vary       on;
        gzip_proxied    any;
        gzip_comp_level 6;
        gzip_types      text/plain text/css text/xml application/json application/javascript application/rss+xml application/atom+xml image/svg+xml;
    }
}
```