Port 23 is used by Telnet Protocol (Telnet). Unencrypted remote access — the predecessor to SSH. Should never be used on modern systems.
What Does an Open Port 23 Mean?
An unencrypted remote access service is running. Telnet transmits all data including passwords in plain text. Any open Telnet port on the internet is a critical vulnerability.
This port should NOT be open to the public internet on typical systems. If you see it open, investigate immediately.
Security Risk Level
Critical Risk
How to Check if Port 23 Is Open
Use the ExamineIP Port Scanner to check if port 23 is open on any IP address from the public internet. Enter the target IP and select the relevant port preset.
How to Close Port 23
- Stop the service using port 23 if you no longer need it
- Add a firewall rule blocking inbound connections on port 23
- Check your router for port forwarding rules that expose this port
- Run
netstat -ano | findstr :23(Windows) to see which process is using it
Related Ports
Telnet is related to: {implode(‘, ‘, Array)}
Protect Your Open Ports
If you need services like remote access, use a VPN to create a private encrypted tunnel instead of exposing ports directly to the internet. A VPN also hides your real IP address so port scanners cannot identify your device. Try PureVPN or IPVanish.