This topic is applicable to scenarios where certain port accesses are blocked for a long time.
A client fails to access the Anti-DDoS Pro IP address of a certain ISP (such as China Telecom) or a certain region (such as Lanzhou). However, the same client can access another Anti-DDoS Pro IP address of a different ISP or region.
- Make sure that the client uses the same ISP network as the destination Anti-DDoS Pro IP address.
- Collect the following basic information: client IP address, ISP information, and the port that cannot be accessed.
- Perform further inspection and acquire the following diagnostic information:
- Screenshot of the Ping test result
- Screenshot of the Port telnet test result
- Full-screen screenshot of the specific error message
- Port route trace record, and result of the Port availability test
- Link testing result (If the ports cannot be pinged, you can use TRACERT or MTR to perform link testing.)
- Once you have identified the issue based on the preceding information, contact the relevant team to solve it.
An Anti-DDoS Pro user has reported that a China Telecom user in ABC city, XYZ province has encountered an exception while accessing Port 80 of an Anti-DDoS Pro instance, but the access port 443 can be accessed normally.
- Collect the following basic information:
- This China Telecom user was in ABC city, XYZ province, and the faulty Anti-DDoS Pro port was 80. The scope of the issue is clear.
- This user can normally access Port 443, it means that the entire link is open, and the problem lies on certain ports.
- We contacted the end user to retrieve the specific IP address: x.x.x.x
- We contacted the end user to retrieve the ping/telnet error messages.
- We contacted the end user to retrieve the comparison between normal and abnormal port accesses.
- Identify the problem. Based on the comparison between normal and abnormal port accesses, the tracking route was disconnected at a network exit in that city.
- Resolve the problem. We contacted the operator to resolve the problem. The problem was caused because of the Municipal jurisdiction security regulation policy.