AS18305: the POSNET POSCO DX network

AS18305 is an internet Autonomous System operated by POSNET POSCO DX (South Korea). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS18305?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS18305 was assigned to POSNET POSCO DX by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS18305 currently announces 35 IPv4 block(s), totaling about 75.3 thousand addresses (75,264 in all), registered in South Korea. Services from POSNET POSCO DX are reached through these addresses.

What it means to see AS18305 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS18305. That means the other end sits on the POSNET POSCO DX network (South Korea). 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.