AS28573: the Claro NXT Telecomunicacoes Ltda network

AS28573 is an internet Autonomous System operated by Claro NXT Telecomunicacoes Ltda (Brazil). Here is what that means and why this number may show up when you investigate a connection on your network.

What is AS28573?

An Autonomous System (ASN) is a block of networks under a single control with its own routing policy on the internet. The number AS28573 was assigned to Claro NXT Telecomunicacoes Ltda by an RIR (regional internet registry). All traffic entering or leaving that network is announced under this number.

Reach on the internet

AS28573 currently announces 197 IPv4 block(s), totaling about 10 million addresses (9,963,776 in all), registered in Brazil. Services from Claro NXT Telecomunicacoes Ltda are reached through these addresses.

What it means to see AS28573 on your network

When you investigate where a connection from your computer or phone comes from (or goes to), you may find AS28573. That means the other end sits on the Claro NXT Telecomunicacoes Ltda network (Brazil). 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.