TCP port 21
You have to have a program that is actually using this port for it to be "open." As long as the program is not blocked by Windows Firewall, the port will be open.
This depends on the OS in use. In Windows, you can open a port by entering its port number through the 'Add port' function of Windows Firewall.
go to your firewall and open port 3074.
Remote assistance port 3389 should be opened.
Port 80.
I can think of two possibilities. I assume since you are asking specifically about Port 1050, that you have a software firewall or a NAT based firewall. Taking a leap into the darkness, is your router by any chance the Netcomm NB5Plus4W as that has a manufacturing defect that causes the port to be open. See the guide guide for port forwarding to close your port if this is your router. http://randompastime.blogspot.com/2010/01/netcomm-nb5plus4w-router-port-1050-open.html It could be malware opening up your port or it could be your firewall.
Port 80 (So your can check your e-mail)
While any unassigned and high level port could be used for SSH it is typically assigned to port 22 on a standard setup. You would need to set up forwarding on that port on your router to the internal IP address in question.
a hidden port is a port that is covered by a firewall
Port 123456 does not exist. To open port 50001 you need to change settings for your port routing tables. Without knowing the exact model of your router it's virtually impossible to help you.
sho port-security int fa0/6
You can check and see like what or you could go to control pannel and then add or remove hardware and check and look at the stuff that's downloaded on your computer. Answer 2: This is caused by "some software" on your computer opening (or mapping) that particular port for communications, or the firewall preventing the opening of that port (software does not always know why it cannot map that port). You would need to find the software that is blocking that port and shut it down, or open the port in the firewall. There is software available that explores what open ports you have, and what it is mapped to. Rather than recommend one over another please search for "port Explorer" at you favorite download or search site. Select the best software for your requirements, and use it to find what is killing that port. Please remember that opening a firewall block on a port could lead to security problems so take caution in your actions.