Unknow issue - please help- Failed logs state failed attemps by unknown user for async??

[johngething]

Hi all,

I seem to be getting lots of failed attemps in my logs that look below.. We have checked the particular device and theirs nothing plugged into it?

Any help would be great.. i have checked this post but there was no valid answer..

https://supportforums.cisco.com/message/852985#852985

Message-Type	User-Name	Caller-ID	Authen-Failure-Code	Author-Failure-Code	Author-Data	NAS-Port
Authen failed		async	Invalid characters in username			tty0
Authen failed		async	Invalid characters in username			tty0
Authen failed		async	Invalid characters in username			tty0
Authen failed		async	Invalid characters in username			tty0
Authen failed	@@	async	Invalid characters in username			tty0
Authen failed		async	Invalid characters in username			tty0
Authen failed	Y[@	async	ACS user unknown			tty0
Authen failed	2	async	Invalid characters in username			tty0
Authen failed	$-	async	ACS user unknown			tty0
Authen failed	(XP	async	ACS user unknown			tty0
Authen failed	PB	async	ACS user unknown			tty0
Authen failed	@	async	ACS user unknown			tty0
Authen failed	%%	async	ACS user unknown			tty0
Authen failed	I	async	ACS user unknown			tty0
Authen failed	$@	async	ACS user unknown			tty0
Authen failed	#NAME?	async	ACS user unknown			tty0
Authen failed	Hm	async	ACS user unknown			tty0
Authen failed	Ii$	async	Invalid characters in username			tty0
Authen failed	%	async	Invalid characters in username			tty0
Authen failed		async	Invalid characters in username			tty0
Authen failed	!I$	async	ACS user unknown			tty0
Authen failed	HI @	async	ACS user unknown			tty0
Authen failed	[	async	ACS user unknown			tty0
Authen failed	m Hm	async	Invalid characters in username			tty0
Authen failed	@[	async	ACS user unknown			tty0
Authen failed	@ @mUL	async	ACS user unknown			tty0
Authen failed	[	async	ACS user unknown			tty0
Authen failed		async	Invalid characters in username			tty0
Authen failed	I	async	ACS user unknown			tty0

[Jagdeep Gambhir]

Hi John,

Do we have any modem or terminal server connected to this device for out of band management? In these type of issues the problem is with the modem or term ser. It echo's back exec information from the console. The console interprets these message as login requests. This is extremely common. If that is the case then we need to reconfigure modem or term server, so that it does not echo.

If it's an IOS terminal server, the "no exec" command resolves the issue.  If it is a modem, it must be reconfigured so that it no longer echoes.

Regards,

~JG

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