Apica has several locations inside of China which enable customers to perform monitoring to simulate the user experience from within the country
This page is intended to outline some of the issues that can occur when using the internet from within China.
The Great Firewall of China
Chinese law requires all traffic entering or leaving China to be filtered through a state controlled firewall. China defines and implements rules to determine whether or not certain content / traffic is permitted.
Occasionally, there are connectivity issues to our agents in China caused by the firewall, which may result in an interruption of monitoring service from those locations. Apica does not receive any advance notification from China if our traffic is impacted.
Should you experience a service degradation to one of our China based locations, Apica support can investigate the issue to determine if there are other causes, or if the location can be changed to improve service. Please contact email@example.com for more information.
You can use this tool to check if a site is blocked in China.
When the firewall finds data that should be prevented, it applies different methods to stop the sender & receiver from communicating.
These methods are applied in different stages of the communication.
Here are some of the common actions, which the firewall is using to block traffic:
- DNS - A sent query from the client returns empty records from the target OR the DNS query is timed out
- Connection - The connection request is either canceled OR timed out
- HTTP Receive - The request from the web browser is sent over HTTP and no response is received which causes a time out
There are certainly more methods used by the firewall to prevent traffic, but these are the most common
When the firewall is preventing certain traffic from passing, the end result will affect end users.
- User navigates to a website with a target url www.xyz.com using a web browser
- The browser starts loading www.xyz.com
- First url completes - from there the browser finds a redirect to URL #2
- The browser requests the the URL #2 www.abc.com/home/index.html
- The request starts loading in the browser - but after 23 seconds its clear that something is wrong
- As URL #2 is not returning - it blocks any other resources from loading which results in a blank screen for the end user in the web browser
- URL #2 loads so long that the web browser finally stop trying which results in an error message to the end user showing that the website timed out.
This is just one example where the time out from the firewall was applied on the HTTP level when sending and waiting to receive a response.
The end game will however be similar, an error page displayed to the end user OR certain components on the website not displayed correctly