Extending a campus network with remote bubbles using IPSec

There is increasing demand for high speed remote connections (e.g. ADSL, cable, etc.) to university networks both from students and staff members. In many instances, the need is to connect not a single computer but a remote subnetwork and to be able to have not only clients but also servers on the remote subnetwork (e.g. to access files on computers on the remote network from workstations in the university). We present a solution to meet these needs through a simple dial-up-like connection to which the access provider allocates only a single temporary IP address to a single remote machine. The solution allows remote networks to be started anytime like little bubbles and be integrated dynamically into the big bubble that is the university network. It is based on the use of IPSec, DHCP and address translation. Beside providing confidentiality, this allows the dynamic allocation of IP addresses in the range of the university to computers in the remote bubble, and binding them to permanent DNS names in the domain of the university. After configuration, the computers in the remote subnetwork appear as if they were located inside the university. The solution can, of course, be applied to any organization.