Scan Interpretation
Decoding the "Closed" state: What your Nmap results are actually saying.
What "Closed" Means
When Nmap labels a port as Closed, it means the target received your packet and sent back a RST (Reset) packet. This is actually a very informative response for an analyst:
- The Host is Up: You cannot receive a "Closed" response from a dead machine.
- No Firewall Blocking: If a firewall (like Windows Firewall or a hardware appliance) were blocking you, the state would be Filtered, not Closed.
- No Active Service: There is no "listening" application (like a Web Server or FTP server) bound to that port.
Security+ Perspective: The Audit Results
Looking at your specific list (FTP, Telnet, SMTP, etc.), this is a Good Security Result. Here is why:
| Port | Status | Security Implication |
|---|---|---|
| 21, 23, 80 | Closed | Insecure legacy "cleartext" entry points are disabled. |
| 25, 110, 143 | Closed | The host is not acting as an unencrypted mail relay. |
| 161, 389 | Closed | Network management and Directory data are not exposed. |
Your Next Move
Since these insecure ports are closed, you should now check for their Secure Counterparts to see how the machine is actually managed:
nmap -p 22,443,636,993,995 [Target_IP]
If port 22 (SSH) and 443 (HTTPS) are open while the others remain closed, the system is following modern security best practices.
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