AS23581: the HYNIX-AS-KR Hynix Semiconductor Inc. network

AS23581 is an internet Autonomous System operated by HYNIX-AS-KR Hynix Semiconductor Inc. (South Korea). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS23581?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS23581 was assigned to HYNIX-AS-KR Hynix Semiconductor Inc. by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS23581 currently announces 5 IPv4 block(s), totaling about 4.1 thousand addresses (4,096 in all), registered in South Korea. Services from HYNIX-AS-KR Hynix Semiconductor Inc. are reached through these addresses.

What it means to see AS23581 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS23581. That means the other end sits on the HYNIX-AS-KR Hynix Semiconductor Inc. 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.