How Does Your IP Reveal Your Location? The Tech Behind IP Geolocation

How is an IP address mapped to a location?

Although an IP address does not directly encode geographic coordinates, it can be traced to a location by following the hierarchy of address blocks, Autonomous System Numbers (ASNs), and the organizations that own them.

An Autonomous System (AS) is a large network or collection of IP prefixes operated by a single entity such as an ISP, a university, or a government agency. Each AS is assigned a unique ASN, which functions like a postal hub routing traffic between networks.

By looking up the ASN associated with an IP address, one can determine the organization that controls the address block and, consequently, the country or region where the address is allocated.

The logical flow can be expressed as:

IP地址 -> 地址块 -> 自治网络编码（ASN） -> 组织 -> 国家

For example, an IP belonging to ASN AS4xxx is known to be allocated to China Telecom in Shenzhen, China. This method typically resolves locations only to the city or district level; finer granularity (street or house) is not achievable through ASN alone.

Law enforcement agencies can obtain more precise location data because ISPs keep detailed records of which customer was assigned a particular IP at a given time. Access to these records requires proper legal authorization.

Privacy concerns of IP addresses

Beyond ISPs, many internet services collect IP‑to‑location mappings to enhance user experience or serve targeted ads. Services like Baidu Maps and Google can reverse‑lookup an IP to an approximate position, sometimes within a few hundred meters.

Even if a user changes their IP via a VPN, nearby devices (e.g., Wi‑Fi, Bluetooth) can still leak location clues, and apps may infer proximity based on network characteristics.

When applications request permission to scan local network devices, users should be cautious. Granting such access can allow the app to enumerate devices, collect MAC addresses, Wi‑Fi SSIDs, and other identifiers, which can then be combined with IP data to build detailed user profiles for commercial purposes.

References

什么是自治系统？| 什么是 ASN？| Cloudflare

IP 地址能精确到什么地步，如何保护隐私？- Luv Letter 的回答 - 知乎

IP 地址能精确到什么地步，如何保护隐私？- Happy Ennding 的回答 - 知乎