Open Port Checker

IP Or Domain
Multiple ports separated by ",", with a maximum of 20 ports allowed at once.

Description

The range of port numbers is from 1 to 65535.
Ports 1 to 1024 are designated by RFC 3232 as "Well Known Ports" and are commonly used for specific services.
Ports from 1025 to 65535 are known as "Dynamic Ports" and can be used for establishing sessions with other hosts, as well as for custom user-defined purposes.
Some common port numbers and their uses are as follows:
  • 21: FTP file transfer service
  • 22: SSH port
  • 23: TELNET terminal emulation service
  • 25: SMTP simple mail transfer service
  • 53: DNS domain name resolution service
  • 80: HTTP hypertext transfer service
  • 110: Port used by POP3 (Post Office Protocol version 3)
  • 443: HTTPS encrypted hypertext transfer service
  • 1433: Default port for MS SQL Server database
  • 1521: Oracle database service
  • 1863: Port used for file transfer in MSN Messenger
  • 3306: Default port for MYSQL
  • 3389: Port used for Microsoft RDP (Remote Desktop Protocol)
  • 5631: Port used for data transfer in Symantec pcAnywhere remote control
  • 5632: Port used for scanning controlled hosts in Symantec pcAnywhere
  • 5000: Port used by MS SQL Server

If your Linux server shows applications listening on a specific port using "lsof -i:", but the online tool indicates that the port is closed, please troubleshoot the following:
1. Verify if the server's firewall allows the port. For Linux, check if iptables and firewalld are active, and temporarily disable them for testing.
2. Check if the server provider's backend has firewall settings that may be blocking the ports.
3. Confirm if the listening application uses the TCP protocol.