This page will serve as a free utility for remotely verifying a port is open or closed. It will be useful for users who wish to check to see if a server is running or a firewall or ISP is blocking certain ports.
How does it work? You give it your IP address, merely by visiting the page, and the page will then probe your network using the port number selected. Most residential ISP’s block ports to combat viruses and spam. The most commonly blocked ports are port 80 and port 25.
Either it says it can see you or it times out on that port. At least you will know if your router or firewall is protecting the port. You can then decide to open or close ports depending on your purpose.
A closed, protected port will produce this message after a few seconds:
Error: I could not see your service on 184.108.40.206 on port (22)
Reason: Connection timed out
You can select from the common ports used by certain software functions:
- FTP 21
- SSH 22
- Telnet 23
- SMTP 25
- Web 80
- Pop 3 110
- IMAP 143
- Other Applications
- Remote Desktop 3389
- PC Anywhere 5631
Port 80 is the default port for http traffic. Port 25 is the default port for sending and receiving mail. ISPs block this port to reduce the amount of spam generated by worms on infected machines within their network.
A simple, effective, single-purpose utility, Open Port Check tool is a free tool provided by No-IP.com. who provide software for network management and security. AJS