树莓派使用requests.post时出现No route to host错误求助

Hey there, let's walk through how to fix this frustrating connection error you're hitting when trying to send a POST request from your Raspberry Pi. That Errno 113: No route to host message means your Pi can't find a valid network path to the target server—here's how to diagnose and fix it step by step:

1. Verify Basic Network Connectivity #

First, rule out fundamental network issues:

• Ping the target domain: Run ping alnnovative.com on your Pi's terminal. If you get no responses or "unknown host" errors, either your DNS isn't resolving the domain, or the server is completely unreachable from your network.
• Ping the server's IP directly: Use nslookup alnnovative.com to get the server's IP address, then ping that IP. If the IP pings successfully but the domain doesn't, you have a DNS configuration problem on your Pi (try switching to public DNS like 8.8.8.8 and 8.8.4.4 in your network settings).

2. Check Firewall & Router Restrictions #

Firewalls (local or network-wide) often block outbound connections:

• Raspberry Pi local firewall: Run sudo ufw status to check if UFW is active. If it is, ensure there's a rule allowing outbound traffic on port 80 (HTTP). If not, add it with sudo ufw allow out 80/tcp.
• Router-level restrictions: Test accessing http://alnnovative.com/security.php from another device on the same WiFi network. If that device also can't reach the site, your router might be blocking the domain or port—check your router's firewall or content filtering settings.
• Target server firewall: It's possible the server's firewall is blocking your Pi's public IP address. Try accessing the site from a different network (like a mobile hotspot) to see if it works.

3. Debug the Connection with Curl #

Use curl to get more detailed connection logs, which can pinpoint exactly where the failure happens:

curl -v http://alnnovative.com/security.php

Look for lines like Could not resolve host (DNS issue) or Connection refused (server/port not open) to narrow down the problem.

4. Double-Check Your Request Code #

While the routing error is the immediate issue, your POST data format might cause problems once connectivity is fixed:
Instead of passing a raw string to data, use a dictionary to ensure the data is sent in the format most servers expect:

import requests
r = requests.post("http://alnnovative.com/security.php", data={"your_param_name": "marium"})

Replace your_param_name with the actual parameter name the security.php script is expecting.

5. Review Your Stack Trace Log #

Your uploaded log file should contain more granular details about the failure—look for entries related to DNS resolution, TCP handshake attempts, or firewall blocks. These will help confirm which step in the network path is breaking.

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