Network technologies and trends » Switch Tips http://itknowledgeexchange.techtarget.com/network-technologies Wed, 15 May 2013 18:52:38 +0000 en-US hourly 1 Make sure to clear ARP http://itknowledgeexchange.techtarget.com/network-technologies/make-sure-to-clear-arp/ http://itknowledgeexchange.techtarget.com/network-technologies/make-sure-to-clear-arp/#comments Tue, 20 Apr 2010 08:30:46 +0000 Yasir Irfan http://itknowledgeexchange.techtarget.com/network-technologies/make-sure-to-clear-arp/  

Most of the times I have noticed, whenever someone configures a NAT in a Cisco PIX firewall 525 or a Cisco ASA firewall, he says my NATing is not working.  This is true especially if you are configuring a NAT for a real IP (which is in use) to private IP. The moment NAT is configured in a firewall he assigns the private IP to his machine and check whether the NAT is working?  Usually it fails to work. The reason behind is the arp cache is not cleared in the firewall, switch and the router.

Next time whenever you configure a NAT for a used real IP make sure you clear the arp by “clear arp-cache” in your Cisco router and Cisco Switch. “Clear arp” in your Cisco firewall . To do so simply use the below command from the privilege mode in your Cisco device

ITKE-ROUTER#clear arp-cache

ITKE-SWITCH#clear arp-cache

ITKE-FIREWALL#clear arp

]]> http://itknowledgeexchange.techtarget.com/network-technologies/make-sure-to-clear-arp/feed/ 0 How to send message to one telnet users from a Cisco Router or Cisco Switch? http://itknowledgeexchange.techtarget.com/network-technologies/how-to-send-message-to-one-telnet-users-from-a-cisco-router-or-cisco-switch/ http://itknowledgeexchange.techtarget.com/network-technologies/how-to-send-message-to-one-telnet-users-from-a-cisco-router-or-cisco-switch/#comments Sat, 16 Jan 2010 05:44:18 +0000 Yasir Irfan http://itknowledgeexchange.techtarget.com/network-technologies/how-to-send-message-to-one-telnet-users-from-a-cisco-router-or-cisco-switch/ In my last article we know how to send a message to all telnet users in a Cisco Router or a Cisco Switch using “send” command. This command can also use to send a message any particular telnet users. It’s quite simple.

Long in to your Cisco Device and look for current telnet users, by using a “show users” command

 

ITKESW01#sho users

    Line       User       Host(s)              Idle       Location

   1 vty 0     netmgr     idle                 00:00:49 10.0.0.5

   2 vty 1     yasir      idle                 00:00:16 10.0.0.5

*  3 vty 2     yasir      idle                 00:00:00 10.0.0.7

 

  Interface      User        Mode                     Idle     Peer Address

 

ITKESW01#

 

 

If you want to send a message to vty session 1 then do as follows.

 

ITKESW01#send 1

Enter message, end with CTRL/Z; abort with CTRL/C:

Dear User netmgr please log off as we need to change your password

^Z

Send message? [confirm]^Z

ITKESW01#

 

 

[kml_flashembed movie="http://www.youtube.com/v/afd-xZ6boZo" width="425" height="350" wmode="transparent" /]

]]> http://itknowledgeexchange.techtarget.com/network-technologies/how-to-send-message-to-one-telnet-users-from-a-cisco-router-or-cisco-switch/feed/ 0 How to send a message to all telnet users from a Cisco Router or Cisco Switch? http://itknowledgeexchange.techtarget.com/network-technologies/how-to-send-message-to-all-telnet-users-from-a-cisco-router-or-cisco-switch/ http://itknowledgeexchange.techtarget.com/network-technologies/how-to-send-message-to-all-telnet-users-from-a-cisco-router-or-cisco-switch/#comments Sat, 09 Jan 2010 10:21:14 +0000 Yasir Irfan http://itknowledgeexchange.techtarget.com/network-technologies/how-to-send-message-to-all-telnet-users-from-a-cisco-router-or-cisco-switch/  

 

Imagine you need to  restart your Cisco Router or a Cisco Switch for some reason, but there are few telnet users logged into your Cisco device. There is a way to send a message to all active telnet users. By using a “send” command from your Cisco Router or a Cisco Switch you can send a message. To do so login to your Cisco Router or a Cisco Switch and type “send*”

 

ITKEAS01# send *

 

Once you enter “send*” in your Cisco Router or a Cisco Switch you will see the following prompt in your device

 

 

Enter message, end with CTRL/Z; abort with CTRL/C:

 

Then you can type your message followed by control Z to send the message to all tty lines.

 

 

This is test message

Please log out of router as we need to restart it^Z

Send message? [Confirm]

ITKEAS01# #

 

 

***

***

*** Message from tty1 to all terminals:

***

This is test message

Please log out of router as we need to restart it

 

 

ITKEAS01#

 

NOTE: When you want to send the message use the CTRL/Z key sequence

[kml_flashembed movie="http://www.youtube.com/v/a6Cg3he_6t8" width="425" height="350" wmode="transparent" /]

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