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Cisco Bug: CSCte23816 - Telnet NOOP command sent to ASA cause next character to be dropped

Last Modified

Nov 09, 2016

Products (1)

  • Cisco ASA 5500-X Series Firewalls

Known Affected Releases

7.2(4) 8.0(4) 8.2(1)

Description (partial)

Administrators connecting to the Security Appliance via a Telnet client may see
times where when they type a character on the command line, 
it is not echoed back - additionally the character is not accepted by the 
Security Appliance.  This occurs if the client is configured to send
a keepalive packet (or anti-idle packet), and the client sends a Telnet NO OP
(No Operation) command to accomplish this.  The Security Appliance will
acknowledge the receipt of the NO OP, but will ignore the next character 
sent after the NO OP.

Customers would observe seeing the following:
--> Admin types "show version"
--> Admin sees "how version" echoed back  (Note the missing 's').

A keepalive or anti-idle feature is enabled on the Telnet client.
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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