IPTool
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TCP port check
Check if a TCP port is open on the specified host. Multiple ports supported.
What it is
Use this tool to test if a TCP port is reachable on a host. Supports IPv4/IPv6 and multiple ports in one request.
How it works
Enter a host (domain or IP), ports separated by comma or space, and optional timeout. The checker tries to open a TCP connection to each port.
Examples
- 22/tcp: SSH
- 80,443/tcp: HTTP/HTTPS
- 25/tcp: SMTP (may be filtered by providers)
Limitations & notes
Only TCP is tested. Firewalls/NAT can filter probes; "closed" may mean filtered. Results reflect connectivity from our server, not globally.
FAQ
- UDP? UDP is connectionless: there is no handshake, many services do not reply to empty probes, and ICMP (port unreachable) is often filtered by firewalls/NAT. Therefore, no response is ambiguous — it proves neither open nor closed. Reliable UDP checks require protocol‑specific payloads and response/timeout analysis, which is out of scope for this tool.
- Is open = safe? No, it only indicates reachability.
- Why timeouts? Hosts may drop packets or throttle scans.