Is there a tool that would let me test connectivity to various servers over various ports?

Question

Recently I've gotten a lot of new servers set up by our networking team for me to develop/test with. The problem is the firewall access I have to the servers is inconsistent, so I need to figure out what ports on what servers I have access to.

Is there an existing tool that could do this?

For example:

• Connect to Server A over port 80 and report success/failure
• Connect to Server A over port 3389 and report success/failure
• Connect to Server A over port 1433 and report success/failure

Ideally I could give it a list of servers and ports to check, and it could give me a list of what failed so I can request the ports to be opened.

Answer 1

 telnet host port

or

 nmap host -p portnum

or

 nmap host -p 1-65535

Answer 2

nmap is the thing you are looking for.

If it is necessary for you to this over Windows, then there is Windows version of the program called zenmap. You'll additionally need to install winpcap for (advanced) port probing with it.

If Linux, a simple bash script would do or just outputing it to file, depends on how will you do it.

Answer 3

Easiest way I can think of is to create a .bat file with a list of paping commands. (As ping does not support port numbers)

paping server1 -p 80 -c 4
paping server1 -p 3389 -c 4  
paping www.google.com -p 80 -c 4
etc.

By looking at the results, you can see which servers you have access to at the moment.