A method for secure external access to a collaborative design system is provided that includes establishing a virtual private network (VPN) tunnel between an engagement virtual machine and an external computer system, wherein the external user provides a user id and password for authorization to establish the VPN tunnel, receiving the user id and password in a web interface of the collaborative design system and identifying the engagement virtual machine the external user is allowed to access based on the user id and password, prompting the external user to log into the engagement virtual machine, wherein the user id and password are again received from the external user, issuing a security ticket to the external user when the user logs into the engagement virtual machine, and using the security ticket to authenticate accesses initiated by the external user to engagement files stored in a file system in an intranet.