Preserving TCP Connections Across Host Address Changes

The predominance of short-lived connections in today's Internet has created the perception that it is perfectly acceptable to change a host's IP address with little regard about established connections. Indeed, the increased mobility offered by laptops with wireless network interfaces, and the aggressive use of short DHCP leases are leading the way towards an environment where IP addresses are transient and last for short time periods. However, there is still a place for long-lived connections (typically lasting hours or even days) for remote login sessions, over the network backups, etc. There is, therefore, a real need for a system that allows such connections to survive changes in the IP addresses of the hosts at either end of the connection. In this paper we present a kernel-based mechanism that recognizes address changes and recovers from them. Furthermore, we discuss the security implications of such a scheme, and show that our system provides an effective defense against both eavesdropping and man-in-the-middle attacks.