Yet it is common knowledge that mobile phones can be geolocated. It simply reflects the fact that ISPs have no need to allocate IP addresses by geographic area, but instead allocate them according to network demand. This is not a fault of the GeoIP service providers. So how much weight should you really put on the accuracy of a geolocated cellular IP if even the world’s leading IP geolocation companies have such low confidence of it being accurate to within 50km, let alone a single city? In the USA this accuracy level is just 12%, with 73% of IPs regarded as incorrectly resolved. In Germany the confidence that an IP address is associated to a specific city is just 16%. The more specific the location, the lower the confidence level. When we look at cellular IPs, the accuracy drops significantly. So what about IP geolocation services like Maxmind? A little digging into their own data accuracy reports will tell you that we need to be extremely cautious about how much weight you attach to the geolocation information that they provide.įor example in Germany, Maxmind state that 83% of their IP addresses are accurately linked to their location – but only to within a 50km radius, and even then only with fixed broadband lines: It’s more accurate to think of them as being grouped by ISP and service type.įor more detailed information on this subject matter I recommend reading these research papers here and also here: IP addresses aren’t organised geographically in the way that old landline numbers used to be. There is no real correlation between a physical location and a cellular IP address. Your IP address also changes very frequently on a cellular network, sometimes as often as every few seconds. Whenever you connect to a 3G or 4G network, you are probably sharing that IP address with thousands of other users at the same time. With mobile IPs the IP shortage problem is even more pronounced. The IP address you have today might be issued to someone else elsewhere in the country tomorrow. You might have the same IP address for a few hours or days, but ISPs constantly juggle and reallocate their IP addresses according to demand. Websites and services generally use IPs that are fixed, but if you’re reading this from your home internet connection then the chances are that you’ve been issued a dynamic IP address by your ISP. A reverse proxy server allows thousands of websites to share the same static IP address, for example. To deal with this shortage, ISPs have developed several workarounds over the years. This was not an issue when the technology was designed in the early 1980s, but now the demand for IP addresses far exceeds supply. The current IPv4 protocol allows for the existence of just under 4.3 billion separate IP addresses. The limitations of IP addresses as geolocation tools are grounded in the technology itself. IP addresses feature prominently in digital investigations, but how useful are they for geolocation? The truth is that while IP addresses have many investigative uses, they can be quite unreliable as a precise geolocation method. This article was written jointly with Matthias Wilson ( It is also published on his own site here. $timestamp = time() + 3600 // one hour valid Security is a secure hash generated from timestamp, path and a salt (in your case just add the ip). The URL gets two parameters - Let's call them s (security) and t (timestamp). There is a really good nginx module doing this.
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