无法通过公网IP访问IIS部署的API求助

Hey there! Since you're new to IIS, let's break down this super common issue step by step—you’ve already tried some online fixes, so let’s cover the most likely culprits you might have missed:

1. Check Server Firewall Rules #

First up, make sure your server’s firewall isn’t blocking incoming requests to your API’s port (default is 80 for HTTP, 443 for HTTPS; adjust if you’re using a custom port):

• Open Windows Defender Firewall > Advanced Settings > Inbound Rules
• Create a new rule: select "Port", enter your API’s port number, choose "Allow the connection", and apply it to all network types (public, domain, private) if needed.
• Don’t forget to check any third-party firewalls or hardware firewalls (like your data center’s) too—these might also block the port. You may need to reach out to your admin if you don’t have access to those.

2. Verify Port Forwarding (NAT) #

If your server is on a local network (like behind a home router or corporate LAN), your public IP belongs to the router, not the server itself. You need to set up port forwarding to route public traffic to your server:

• Log into your router’s admin panel (usually via 192.168.1.1 or similar)
• Look for "Port Forwarding" or "NAT Rules"
• Add a rule that maps your public port (e.g., 80) to your server’s local IP (e.g., 192.168.1.100) and the same internal port. Save the changes and test again.

3. Fix IIS Site Bindings #

Chances are your IIS site is only bound to localhost or your server’s local IP, which means external requests can’t find it:

• Open IIS Manager, find your API site, right-click > Edit Bindings
• Either modify an existing binding or add a new one: set the "IP address" to "All Unassigned" (so it listens on all available IPs) or directly enter your server’s public IP if it’s assigned to the server.
• Remove any host header values unless you’re using a domain (and have set up DNS pointing to your public IP)—host headers block IP-based requests.

4. Rule Out ISP Port Blocking #

Some ISPs (especially home broadband providers) block common ports like 80 or 443 to prevent hosting public services. Try switching to a less common port (like 8080 or 8888):

• Update your IIS site binding to use the new port
• Adjust your firewall rules and port forwarding to match the new port
• Test access using http://your-public-ip:new-port

5. Use Testing Tools to Diagnose #

• On an external device, run this PowerShell command to check if the port is reachable:

  Test-NetConnection your-public-ip -Port your-api-port
  

  Look for TcpTestSucceeded : True—if it’s false, the port is still blocked somewhere.
• Try accessing the public IP + port from the server itself. If that fails, the issue is on the server (firewall or IIS config), not the network.

内容的提问来源于stack exchange，提问作者Asifuzzaman