What is Port Checker ?

Port Checker is a simple and free online tool for checking open ports on your computer/device, often useful in testing port forwarding settings on a router. For instance, if you're facing connection issues with a program (email, IM client etc) then it may be possible that the port required by the application is getting blocked by your router's firewall or your ISP. In such cases, this tool might help you in diagnosing any problem with firewall setup. You could also find this useful for security purpose, in case you're not sure whether a particular port is open or closed. If you host and play games like Minecraft, use this checker to make sure the server port(25565) is configured properly for port forwarding, then only your friends will be able to connect to your server.

Most Commonly Used Ports

Port numbers ranges from 1 to 65535, out of which well known ports are pre-defined as convention by IANA.

0-1023 - Well known ports (HTTP, SMTP, DHCP, FTP etc)

1024-49151 - Reserved Ports

49152-65535 - Dynamic/Private Ports

Well known ports

20 & 21 - FTP (File Transfer Protocol)

- FTP (File Transfer Protocol) 22 - SSH (Secure Shell)

- SSH (Secure Shell) 23 - Telnet, a Remote Login Service

- Telnet, a Remote Login Service 25 - SMTP (Simple Mail Transfer Protocol)

- SMTP (Simple Mail Transfer Protocol) 53 - DNS (Domain Name System)

- DNS (Domain Name System) 80 - HTTP (Hypertext Transfer Protocol)

- HTTP (Hypertext Transfer Protocol) 110 - POP3 (Post Office Protocol 3)

- POP3 (Post Office Protocol 3) 115 - SFTP (Secure File Transfer Protocol)

- SFTP (Secure File Transfer Protocol) 123 - NTP (Network Time Protocol)

- NTP (Network Time Protocol) 143 - IMAP (Internet Message Access Protocol)

- IMAP (Internet Message Access Protocol) 161 - SNMP (Simple Network Management Protocol

- SNMP (Simple Network Management Protocol 194 - IRC (Internet Relay Chat)

- IRC (Internet Relay Chat) 443 - SSL / HTTPS (Hypertext Transfer Protocol Secure)

- SSL / HTTPS (Hypertext Transfer Protocol Secure) 445 - SMB

- SMB 465 - SMTPS (Simple Mail Transfer Protocol over SSL)

- SMTPS (Simple Mail Transfer Protocol over SSL) 554 - RTSP (Real Time Stream Control Protocol)

- RTSP (Real Time Stream Control Protocol) 873 - RSYNC (RSYNC File Transfer Services)

- RSYNC (RSYNC File Transfer Services) 993 - IMAPS (Internet Message Access Protocol over SSL)

- IMAPS (Internet Message Access Protocol over SSL) 995 - POP3S (Post Office Protocol 3 over SSL)

- POP3S (Post Office Protocol 3 over SSL) 3389 - RDP (Remote Desktop Protocol)

- RDP (Remote Desktop Protocol) 5631 - PC Anywhere

- PC Anywhere 3306 - MySQL

- MySQL 5432 - PostgreSQL

- PostgreSQL 5900 - VNC

- VNC 6379 - Redis

- Redis 11211 - Memcached

- Memcached 25565- Minecraft

If you're looking for a full list of port numbers check out this wikipedia page. I've listed all the common ports above, feel free to enter any custom port number to check. By default, this site is taking your device's IP address as target ip address (the device through which you're visiting this web page), but you can change the IP input field to check for other IP addresses - remote clients and servers as well. But, please don't misuse this option otherwise, I would have to restrict the IP address to source again (as I had done earlier). Please keep in mind that if you're using a VPN or proxy server then it may not be able to get your device's IP correctly.

Understanding Port Forwarding

Port forwarding or port mapping involves translating the address (or port number to a new destination), accepting the packets and forwarding it (using routing table). It's typically used in connecting remote computers to specific programs running on computer (in a private LAN (Local Area Network)). For example : running a public server (HTTP, port 80) on a computer in a private LAN or granting SSH access to a specific computer in a private LAN etc. Read More on Wikipedia.

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