Security email alert sent to administrators

I just received this email:

There has been 2 unsuccessful attempts to log into ‘[your URL]’using 2 Employee Code ’000264′ & ’000262′. Therefore that IP address has been banned for an hour.

Details of the IP banned:
IP : 123.123.123.123
Location: CANADA – XXXXXXXX

This means that someone (and it may be the same person) has tried to log into the site with 2 different employee codes. This may be a legitimate attempt by an employee, but it could also mean a brute attack with a person or automated system trying different employee codes. To protect your site, we temporarily blocked that IP from trying to log in, and email you a warning.