I want to log all failed and successfull login attempts to my Router.

I have already done a
   logging host <my syslog Server>

And it logs some information (like when a config is changed).

I have tried a
   logging trap informational

I did a logging trap debug and did a debug ALL - but it was WAY too much
information.

Is there any way to log telnet authentication attemps (success and failures)

James Roper