telnet SMIS on port 5988

[Tejas Saner]

I tried to telnet SMIS on port 5988 or 5989 but I had no answer, is it because the port uses UDP protocol?

Can any one help me regarding this?

Thank you
Tejas

[Paul von Behren]

First – SMI-S/CIM does *not* use UDP, it uses TCP (FYI “HTTP over anything” implies TCP).  SMI-S also uses SLP which uses UDP and TCP, but the SLP agents are at port 427.

 

I assume you realize you can’t do full-fledge telnet (i.e. invoke a shell) through telnet to a CIMOM, but telnet does help test whether anything is listening.   Unfortunately the way you determine whether something is listening is to differentiate error messages from the client (your telnet tool) and the server.  Best way to see what your telnet client reports when nothing is listening is to pick a port you are pretty sure is not being used.  You should see a message quickly along the lines of “could not open connection”.  If that is what you are seeing at 5988 or 5989, then it seems like no CIMOM is listening. 

 

If you connect to an SSL/TLS port (5989) and there is a listener, you will probably lock up your client since telnet expects text and the SSL traffic is encrypted.  In this case, CTL-] is a common escape character, will bring up and out-of-band prompt and you can type ‘quit’.    With Windows built-in telnet and Pegasus, the screen clear at 4989 and I can hit enter and the cursor moves down.  But that’s about it.  Then it’s time to escape J  One note – if you telnet to a shell on one system, then use telnet to test the connection, then  escape/quit, you lose the shell session.  Another good reason to use SSH for remote shell access. 

 

If you connect to a non-SSL/TLS port (5988), the screen should clear and you should be able to hit retuen and see the cursor move down.  After a couple of these you may see an HTTP error.  If you can type a well-formed HTTP request, you might see a response.  I personally am not a good enough typist to get a CIM over XML over HTTP request typed in correctly.  You can exit here without the escape (I think the commend is ‘quit’). 

 

Since CIM is based on HTTP, you can also diagnose with a web browser.  CIM does not do HTML, so you won’t see pretty web pages. When I point Firefox to my Pegasus server at 5989, it tells me the server has an invalid certificate (I don’t have a certificate installed).    Then I hit “back” knowing that there is an SSL/TLS listener on 5989.

 

So my diagnostic arsenal is to use telnet for non-encrypted CIM and Firefox for encrypted CIM. 

 

Hope this helps!

 

Paul