Deno Get Client IP Address: Remote User IP 🫱🏾‍🫲🏼 # Deno Get Client IP Address: Remote User IP 🫱🏾‍🫲🏼 #

📹 Video #

🖥 Deno Get Client IP Address: Code #

    
1 import { healthCheck } from "@/routes/health_check.ts";
2 import { logRequest } from "@/utilities/logging.ts";
3 import { load } from "@std/dotenv";
4 
5 await load({ export: true });
6 
7 const PORT = 8080;
8 
9 function remoteAddress(
10   connectionInfo: Deno.ServeHandlerInfo
11 ): string | undefined {
12   const { remoteAddr } = connectionInfo;
13   if (!("hostname" in remoteAddr)) {
14     return undefined;
15   }
16 
17   const { hostname } = remoteAddr;
18   return hostname;
19 }
20 
21 const handler: Deno.ServeHandler = (request, connectionInfo) => {
22   const { method, url } = request;
23   const { pathname } = new URL(url);
24   logRequest(request);
25 
26   switch (pathname) {
27     case "/health_check": {
28       if (method === "GET") {
29         const response = healthCheck();
30         return response;
31       }
32       const response = new Response("Method Not Allowed, {status: 405}");
33       return response;
34     }
35     case "/v0/ip-example": {
36       if (method === "GET") {
37         const { headers } = request;
38 
39         const denoIP = remoteAddress(connectionInfo);
40         const xForwardedIP = headers.get("X-Forwarded-For") ?? undefined;
41         const cloudflareIP = headers.get("CF-Connecting-IP") ?? undefined;
42 
43         console.log({ denoIP, xForwardedIP, cloudflareIP });
44 
45         const finalAnswer = cloudflareIP ?? xForwardedIP ?? denoIP;
46 
47         console.log({ finalAnswer });
48 
49         const response = new Response("OK");
50         return response;
51       }
52 
53       const response = new Response("Method Not Allowed, {status: 405}");
54       return response;
55     }
56     default: {
57       const response = new Response("Not Found", { status: 404 });
58       return response;
59     }
60   }
61 };
62 
63 Deno.serve({ port: PORT }, handler);

  

🔗 Links #

• Deno Fresh testing article
• Cloudflare HTTP request headers docs 
• GitHub repo with full code 
• Element chat: #Rodney matrix chat 
• Twitter handle: @askRodney 

🏁 Deno Get Client IP Address: Summary #

How can you access remote user IP address in Deno? #

The Deno HTTP server provides connection information metadata. You can access this meta from the parameters on the server handler function. The first parameter is the request, and the second, is the connInfo object. From connInfo, destructure remoteAddr.hostname. Typically, that hostname will be the connecting IP address as a string. This might not be the remote client IP address, though. For example, if the DNS for your Deno server is proxied through Cloudflare, the hostname will be a Cloudflare IP, instead. In this case, consider using the X-Forwarded-For HTTP header or a Cloudflare CF-Connecting-IP header.

How can you get remote client IP address on a Deno server behind a Cloudflare proxy? #

If your server is behind a Cloudflare (or other proxy), the Deno APIs will probably give you the proxy address, rather than the remote client IP address as the remote address hostname. As an alternative, look for the CF-Connecting-IP HTTP header on the incoming request.

What is the X-Forwarded-For HTTP header? #

When a client connects to your server via a proxy, the remote IP address, seen from your server, will appear to be the proxy IP address and not the remoter user’s IP. However, some proxies (Cloudflare, for example) will normally add the X-Forwarded-For HTTP header. The header value will be the remote user’s IP address; and this header makes the remove client IP address available to your server. When the request passes through multiple proxies, each will add their (adjacent) connecting IP to the header value. The header value can, therefore, be a comma separated list of IP addresses, which the request passed through. The remote client IP will be the first. Be sure to comply with appropriate privacy regulations when using the client IP address.

🙏🏽 Feedback #

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Rodney

@askRodney

Just dropped a new video on how you can access remote client IP address form your 🦕 Deno server. Handy when running spam/bot detection.

Hope you find it useful!

#learndenohttps://t.co/Fak0uehRMI

— Rodney (@askRodney) July 14, 2023

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