Port Checker allows you to discover which ports are open on your target host. This is Free Web-based port scanning service to test your firewall or other devices. Online Port Scanner Tool is 100% Free tool to check ports for FTP, SSH, Telnet, SMTP, DNS, HTTP, POP3, SFTP, NTP (Network Time Protocol) etc.
Online Port Scanner allows you to check a host or IP for an open or listening port, useful for checking port in your router is open or close.
Ports are virtual pathways on which information on the Internet travel. There are 65,536 ports to choose from. A good analogy is to think of ports like extensions on a phone sytstem.
Ports 0 to 1023 - Well known port numbers. Only special companies like: MS SQL services (1433), Mail services POP3(110), IMAP(143), SMTP(25), Web services HTML(80).
Ports 1024 to 49151 - Registered ports; meaning they can be registered to specific protocols by software corporations.
Ports 49152 to 65536 - Dynamic or private ports; meaning that they can be used by just about anybody.
Port Forwarding is a special function on the router, allowing transfer of data packets from the outside (from the Internet) to devices or computers on your local network (LAN). Usually the port on your router will be closed to prevent hackers on your system. But when you use the service to connect through port on the router you need to open it. For example: Yahoo! Messenger you need one of the following ports must be open: 5061, 443, 80.
| FTP Control | 21 |
| SSH | 22 |
| Telnet | 23 |
| SMTP | 25 |
| DNS | 53 |
| HTTP / Web | 80 |
| POP3 | 110 |
| IMAP | 143 |
| HTTPS | 443 |
| IMAP SSL | 993 |
| POP3 SSL | 995 |
| MSSQL | 1433 |
| REMOTE | 3389 |
| VNC | 5900 |
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