How can I test whether a port is open on a firewall?

[Carl Galt]

I travel a lot and use wifi in a lot of different places (hotels, airports, etc.)

My apps don't always work and I suspect that in some instances the broadband provider is blocking some of the ports I need.

I don't need a port scanner like NMAP since that scans a target IP for listening ports. What I need is a way to figure out whether some firewall between my PC and the Internet is blocking specific UDP or TCP port ranges.

 

[ProtocolGeek]

I travel a lot and use wifi in a lot of different places (hotels, airports, etc.)

My apps don't always work and I suspect that in some instances the broadband provider is blocking some of the ports I need.

I don't need a port scanner like NMAP since that scans a target IP for listening ports. What I need is a way to figure out whether some firewall between my PC and the Internet is blocking specific UDP or TCP port ranges.

Firebind is a site that was designed for this purpose. They have a java app that can test any of the 65535 TCP or UDP ports to see whether there is a firewall blocking them.

You can test a single port or a range of ports. They also have some canned tests.

www.firebind.com

 

[Carl Galt]

Best answer selected by Carl Galt.