AS133405: the RETNKK-AS-AP RETN Co., Ltd. network

AS133405 is an internet Autonomous System operated by RETNKK-AS-AP RETN Co., Ltd. (Japan). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS133405?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS133405 was assigned to RETNKK-AS-AP RETN Co., Ltd. by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS133405 currently announces 1 IPv4 block(s), totaling 256 addresses (256 in all), registered in Japan. Services from RETNKK-AS-AP RETN Co., Ltd. are reached through these addresses.

What it means to see AS133405 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS133405. That means the other end sits on the RETNKK-AS-AP RETN Co., Ltd. network (Japan). 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.