How IP Addresses Reveal Geographic Locations and Their Privacy Implications

Source: Authorized repost from public account "Chen Shuyi"

Author: Chen Shuyi

To further standardize domestic online public opinion, the state requires all internet platforms to display IP location information. Platforms such as Weibo, Douyin, and public accounts have launched IP location features, marking a step toward tighter regulation of online speech. But how do these platforms locate a user's region from an IP address, what is the underlying principle, and what practical applications does IP geolocation have? This article explores the technical foundations behind IP location.

How to Find an Address Using an IP?

We all know that an IP address can be used to locate a person, yet the IP address is not directly tied to a geographic location. The mapping is achieved through Autonomous Systems (AS).

The Internet consists of many networks; an Autonomous System is a large network that connects to the Internet. Every device connected to the Internet belongs to an AS, each identified by an Autonomous System Number (ASN).

Think of an AS as a town's post office. Mail moves from one post office to another until it reaches the correct town, where the local post office distributes it to all addresses within that town. Each AS controls a specific block of IP addresses, similar to how a town's post office handles mail for its area. Typically, an AS is operated by a single large organization such as an ISP, a major tech company, a university, or a government agency.

The logical chain can be expressed as: IP address → address block → Autonomous System Number (ASN) → organization → country Through this chain, an IP can be mapped to a rough location, e.g., Beijing Chaoyang District or Shenzhen Nanshan District. For example, my current IP belongs to the ASN AS4xxx , which indicates the organization China Telecom and a location in Shenzhen, China.

While an ASN can pinpoint a location only to the county or district level, finer granularity is not directly available. However, because ISPs keep detailed allocation records for each IP block, law enforcement with proper authorization can retrieve the exact subscriber information, enabling precise location tracking. Such queries are restricted to authorized personnel and require legal procedures.

Privacy Issues of IP Addresses

Is it only the ISP that can discover a person's address? In the era of big data, many internet services collect extensive data and can infer a user's approximate location from IP information. For instance, Baidu Maps records IP‑location associations via its SDKs and web interfaces, allowing reverse lookup with accuracy potentially within a few hundred meters.

Foreign companies also perform similar practices; for example, Google provides location services based on IP, though they disclose data usage policies more transparently and offer users options to disable such features.

Using a VPN to change your IP does not guarantee anonymity, because nearby devices (Wi‑Fi, Bluetooth) can betray your real location. If a neighboring device shares similar network characteristics, services may infer that you are close to that neighbor, even if your IP is masked.

When applications request permission to scan local devices, users should be cautious. Unless the request is for a legitimate local NAS or screen‑casting scenario, granting it can expose personal information. Malicious apps may scan the LAN, collect IP addresses, device identifiers, Wi‑Fi details, and then combine this data for targeted advertising—for example, showing real‑estate ads after you search for housing on a computer.

In summary, the "find and connect to local network devices" feature simplifies cross‑platform advertising but raises significant privacy and security concerns for users.

References

What is an Autonomous System? What is an ASN? – Cloudflare

How precise can an IP address be, and how to protect privacy? – Luv Letter (Zhihu)

How precise can an IP address be, and how to protect privacy? – Happy Ending (Zhihu)