Microsoft has long encouraged its employees to 'RAS' into the corporate network from home or from the road to access e-mail, shared files and applications. RAS, short for Remote Access Services, is an old Microsoft term for what most people now call a client VPN. Microsoft, of course, maintains valuable intellectual property on its internal network, including the source code to all its operating systems and applications. These are constant targets for hackers, and Microsoft tries to protect its most valuable assets with defenses in depth; they are behind firewalls and on networks segmented with IPsec. In addition, the entire network is monitored for suspicious activity, scanned for malware and so on.