telnet with port

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Apr 18th, 2008
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Hi, when i m going telnet with specific port to any server from 3750 switch, in some cases its showing "Trying 192.X.X.X, 6000 ... No listener..." please can you tell me where is the problem.


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goutam_04 Fri, 04/18/2008 - 03:06
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what may be the causes, what should i do to telnet with a specific port.

hobbe Fri, 04/18/2008 - 03:12
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well first you need to install a telnet server, in your telnet server configuration you tell the telnet server to listen to a specific port.


The easiest way to do things like this just for testing purposes is to use an realy old program called Netcat.


Then we have the small problem of firewalls, if the host has a software firewall you would need to configure it to let the desired ports through.


And of course all routing and firewall/nat issues. but that is a different question.


goutam_04 Fri, 04/18/2008 - 03:21
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when i m trying with 23/80 it is ok, telnet is getting fine. but when i m trying with other ports its not happening..

goutam_04 Fri, 04/18/2008 - 03:35
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yes, some application needs to connect through different ports, so I need to check the port is open or not.

Rick Morris Fri, 04/18/2008 - 06:05
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there is a ping utility called slping.


It will ping on any port you specify. I uploaded the program once before, it is a .exe program.

Here is the link with instructions too.


http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Service%20Providers&topic=VPN%20Service%20Architectures&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40%5E1%40%40.2cbeb94e/7#selected_message


This will tell you if the device is open for any port number. If not then you will need to go to the server and do a netstat -a to see if the port is listening or established.

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