How to use Telnet to check connections to services

At Cloud FastPath, we move massive amounts of content into Cloud Collaboration Platforms. Cloud FastPath’s on-premises agent is how we connect Cloud FastPath’s service to file servers, on-premises SharePoint deployments, and other NAS. Many of our customers have dozens if not hundreds of different on-premises storage systems, all with unique configurations.

Since Cloud FastPath moves data out of highly secure on-premises environments, our customers and support teams need to test and configure connectivity with tools like Telnet.

In this very basic snippet/example of Telnet use, we are testing to see if a particular machine can communicate with other services, in this case, the Cloud FastPath migration infrastructure. We also use the NSLOOKUP command to see if there are any problems resolving the address

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:: Open up a command prompt:
:: Windows Key + R to open the Run window
:: Enter cmd and hit OK
 
:: Run the command:
pkgmgr /iu:"TelnetClient"
 
::This will confirm you have installed and updated telnet. Wait a few seconds and then enter:
telnet www.google.com 443
 
:: If the screen clears, and presents you with a blinking cursor, you have successfully connected.
:: Hit CTRL + ], and then enter 'quit' to return to the command prompt. 
:: It may also eventually just timeout and return you to the command prompt, but again, you will not receive any visual confirmation other than the blank screen and blinking cursor.
:: To see what a failure looks like, try something like 
 
telnet www.google.com 444
 
:: It will hang for a moment, and then present you with:
 
:: C:\Users\Ian>telnet www.cloudfastpath.com 444
:: Connecting To www.google.com...Could not open connection to the host, on port 444: Connect failed
 
:: Great, now that we know how to use telnet, we can troubleshoot connectivity issues to the Cloud FastPath service:
 
telnet www.cloudfastpath.com 443
 
telnet ctl.www.cloudfastpath.com 443
 
:: If those are working, we know we can successfully connect to the CFP services. 
 
:: We can also use NSLOOKUP to see if there is an issue resolving these addresses. With an NSLOOKUP, we want to see something like this:
 
nslookup www.cloudfastpath.com 
nslookup ctl.www.cloudfastpath.com
 
:: C:\Users\Ian>nslookup www.cloudfastpath.com
:: Server:  pioneer2.cictr.com <- Locally cached results
:: Address:  10.50.200.3
 
:: Non-authoritative answer: <- but that should still give us the actual IP of Cloud FastPath
:: Name:    www.cloudfastpath.com
:: Address:  54.197.253.183
 
:: C:\Users\Ian>nslookup ctl.www.cloudfastpath.com
:: Server:  pioneer2.cictr.com
:: Address:  10.50.200.3
 
:: Non-authoritative answer:
:: Name:    ctl.www.cloudfastpath.com
:: Address:  54.197.254.170