AS31223: the EA-UK-LHR network

AS31223 is an internet Autonomous System operated by EA-UK-LHR (the United Kingdom). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS31223?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS31223 was assigned to EA-UK-LHR by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS31223 currently announces 2 IPv4 block(s), totaling about 2 thousand addresses (2,048 in all), registered in the United Kingdom. Services from EA-UK-LHR are reached through these addresses.

What it means to see AS31223 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS31223. That means the other end sits on the EA-UK-LHR network (the United Kingdom). It can be legitimate — a cloud service, an ISP, a CDN — or an unexpected connection worth checking.

How to see every connection and network your devices reach

Tracing one connection's ASN at a time is tedious. Sentinela, by PC Monitor, maps the devices on your network, shows what is exposed to the internet and helps flag suspicious connections and devices — running on your Windows. Meet Sentinela.