AS17931: the NETFOREST Netforest,Inc. network

AS17931 is an internet Autonomous System operated by NETFOREST Netforest,Inc. (Japan). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS17931?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS17931 was assigned to NETFOREST Netforest,Inc. by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS17931 currently announces 7 IPv4 block(s), totaling about 20.5 thousand addresses (20,480 in all), registered in Japan. Services from NETFOREST Netforest,Inc. are reached through these addresses.

What it means to see AS17931 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS17931. That means the other end sits on the NETFOREST Netforest,Inc. 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.