logon failed

From: Tom (sonlas@homtail.com)
Date: 02/17/03 

From: "Tom" <sonlas@homtail.com>
Date: Mon, 17 Feb 2003 14:10:55 -0800

I am using NT 4.0 server sp6a and SQL Server 7.0 sp3.
Sometiems i am getting in event view SQL log, logon failed
for users (database, sa, root, admin and so on). I have no
idea how can they try to access the SQL server and i don't
know if they gain access too. Any idea?

Thank you in advance.