Hong Kong servers can be used in mainland China, but connectivity issues may arise in certain situations, making them inaccessible. This article will provide a detailed analysis of these issues and offer corresponding solutions to help you fully utilize the advantages of server rental.

Possible Reasons for Servers Being Unusable in Mainland China

Although Hong Kong servers can be accessed normally in mainland China most of the time, occasional connection failures may occur. Here are a few common reasons:

  1. Network operator restrictions: Mainland operators may impose restrictions on certain IP ranges or ports, affecting server reachability.
  2. DNS resolution anomalies: DNS pollution or hijacking can prevent domain names from correctly resolving to server IPs, making it impossible to establish connections.
  3. Server security settings: If the server’s firewall rules or security group settings are too strict, they may also block access from mainland China.

Testing Server Connectivity

To verify whether a server can be accessed normally from mainland China, we can use some simple network tools for testing. For example, we can use the ping command to check the server’s response time and packet loss:

ping your_server_ip

Additionally, we can use the telnet command to test the connectivity of specific ports (such as port 80 for HTTP):

telnet your_server_ip 80

If the ping test shows request timeouts or high packet loss rates, or if telnet cannot establish a connection with the server, it indicates connectivity issues that need further investigation and resolution.

Solutions for Inaccessible Servers in Mainland China

Once connectivity issues are confirmed, we can try the following solutions:

1. Using VPN or Proxy Services

By using reliable VPN or proxy services, we can bypass network restrictions imposed by operators and achieve stable access. Here’s an example of using Python to implement a SOCKS5 proxy:

import socket
import socks

socks.set_default_proxy(socks.SOCKS5, "proxy_host", proxy_port)
socket.socket = socks.socksocket

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("your_server_ip", server_port))

2. Modifying DNS Resolution Settings

If the problem lies in DNS resolution, we can try modifying local DNS settings to use reliable public DNS services (such as Google DNS or OpenDNS). Here are the steps to modify DNS settings in Windows:

ipconfig /flushdns
netsh interface ip set dns "Ethernet" static 8.8.8.8
netsh interface ip add dns "Ethernet" 8.8.4.4 index=2

3. Optimizing Server Security Settings

Sometimes, connectivity issues may originate from the server’s own security settings. We need to check firewall and security group rules to ensure necessary ports (such as port 80 for web services) are open. Here’s an example of opening port 80 on a CentOS system:

sudo firewall-cmd --zone=public --add-port=80/tcp --permanent
sudo firewall-cmd --reload

In summary, although Hong Kong servers may occasionally encounter connectivity issues when used in mainland China, they can still be accessed normally in most cases. When connection failures occur, we can solve them by using VPN proxies, optimizing DNS resolution, and adjusting server security settings.