CIRCUITO
CARIOCA TI · DOCUMENTATION
♙
Network diagnostics

Port Check

Test TCP connectivity to a port on a validated public IPv4 or IPv6 target from the portal server.

TCPPortIPv4IPv6Connectivity

TCP port test

Attempts one TCP connection from the Circuito Carioca TI server to one validated public IP and port.

Examples: example.com, 1.1.1.1 or 2606:4700:4700::1111
TCP

What an open result proves

An open result means this server completed the TCP connection establishment to the selected IP and port. It confirms transport-level reachability from the portal server, but it does not verify that the expected application protocol is healthy, authenticated or correctly configured.

FAILURE

Closed, filtered and unreachable are not identical states

A TCP refusal is different from a timeout. A refusal is commonly associated with an active rejection, while a timeout can be caused by filtering, packet loss, routing or an unresponsive destination. Because this tool performs only a normal TCP connect attempt, it reports what the server observed without claiming a complete firewall diagnosis.

DNS / SSRF

The socket never reconnects using the submitted hostname

For hostnames, all resolved IPv4 A and IPv6 AAAA addresses must be public. The tool then selects one validated address and opens the TCP socket directly to that literal IP. This avoids a second DNS resolution during the connection and reduces DNS rebinding or pinning risk.

ORIGIN

The result represents the hosting server

The connection originates from the Circuito Carioca TI hosting environment. Firewalls, routes, carrier policies and geographic paths can differ completely from those seen by the visitor.

FAQ

Frequently asked questions

What does an open port result mean?+

It means the Circuito Carioca TI server successfully established a TCP connection to the selected public IP and port.

Does an open TCP port mean the application is working?+

Not necessarily. The TCP connection can succeed while the application protocol, authentication or service behind the port is unhealthy.

What does connection refused mean?+

It generally means the destination actively rejected the TCP connection, commonly because no service is accepting connections on that port. Network devices can still influence the result.

Does a timeout prove that a firewall is filtering the port?+

No. Filtering is one possibility, but packet loss, routing problems and an unresponsive destination can also cause a timeout.

Does the tool support IPv6?+

Yes. Public IPv6 literals and IPv6-only hostnames are supported when the hosting server has IPv6 connectivity.

Can I test private or localhost addresses?+

No. Private, loopback, link-local, reserved and other non-public destinations are intentionally blocked.

Why does the tool resolve a hostname before connecting?+

It validates every returned A and AAAA address and then connects directly to one validated literal IP, avoiding a second DNS resolution during the socket connection.