vRealize Orchestrator – using Telnet to test port connectvitiy

vRealize Orchestrator has a TelnetClient scripting class that you can use to test port connectivity. This is far easier to use than dropping to a telnet client on a cli and test connectivity that way. Together with using the TelnetClient scripting class and a workflow that would loop and wait for the port to be open, fail gracefully or continue the workflow but notify that connectivity wasn’t available, the options the TelnetClient scripting class gives you are very handy.

Here a screenshot of what the scripting class looks like in the API browser:

Screen Shot 2015-03-08 at 11.19.18

The constructor looks like this:

var telnet = new TelnetClient(string)

The parameter is a string and takes a terminal type, which be default is VT100. Other terminal types would be ANSI, VT52, VT102, VTNT and so on. VVT stands for video terminal so mostly you can use the default value of VT100.

Here is some simple code to test telnet connectivity:

var port = 22; // number
var target = "localhost"; // string

try {

// testing for port connectivity on target host
System.log("Trying to connect to port " + port + " on host  " + target);
var telnet = new TelnetClient("vt100") ;
telnet.connect(target, port);
connectionSuccess = telnet.isConnected();
System.log("Connectivity to target host " + target + " is successful")

} catch (e) {

connectionSuccess = telnet.isConnected();
System.log("Connection failed: " + e)

} finally {



The isConnected() method returns a boolean of true or false, depending on the connection result, so together with this block of code and a loop workflow, you can test connectivity to a telnet port or wait for a socket to be up. Using a try / cath / finally statement, you catch any errors and disconnect appropriately, although strictly speaking disconnec() can go in the try statement as you’ll only ever connect in the try block so you can only ever disconnect there as well. Skin a cat in several ways on that one. Up to you 🙂

Here’s a screenshot of a workflow that puts it all together. The decision just checks for true or false which is set depending on the connection response.

Screen Shot 2015-03-08 at 11.27.05

Obviously in the sample code above, you should configure the inputs appropriately for the target and the port. This is also a good way to check if a service is available, for example check for SMTP or a REST API service by using telnet.

Happy telnetting!






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