As an application developer, network admin, security admin, or anyone who is responsible for communications between one device to another it is important to know how to verify your basic ports and their access.

For instance you should have found by now that you cannot ping the specific port however in several cases you can telnet to the specific port.  Below are the basic protocols and their ports:

HTTP      – 80
FTP         – 21
TELNET – 23

Now, in order to test you will need to open a command prompt.  For this exampe we will use the FTP port:

telnet servername 21

You should see the following as a result:


If you see the above you have successfully connected.  If anything other you will want to check where the port may be blocked.  A few places you will find this blocked could be the operating systems firewall, a group policy (usually in a corporate environment), or a network setting blocking the port.