How to find out or check whether a port is open ?

Hi,

I want to know that, is there an easy way to find out if a port is open on someones computer. Is their any built in command line tools for this? Maybe a freeware utility?

Hi,

You can use open port checker tool with this you can check your external IP address and detect open ports on your connection. This tool is useful for finding out if your port forwarding is setup correctly or if your server applications are being blocked by a firewall. This tool may also be used as a port scanner to scan your network for ports that are commonly forwarded. It is important to note that some ports, such as port 25, are often blocked at the ISP level in an attempt to prevent malicious activity.

Hi,

Port Detective 2.0 is a freeware that helps find out what ports are blocked by your router/firewall or ISP. Useful in testing which ports are blocked, in-use or open. Can be used with Cable or DSL connections so users can host their own photo server,website, FTP and mail server, etc. Many times the ISP or local router or firewall will block ports making self-hosting impossible.

You can also check by opening a command prompt. Go to "START" and click on "RUN" type "cmd" and type command "netstat -a" and then you will get up a list so showing you poeple who are connected to your computer.