Backdoors is a novel system architecture that enables remote monitoring and recovery/repair of the software state of a computer system without using its processors or relying on its OS resources. We have implemented a Backdoors prototype in the FreeBSD kernel using Myrinet NICs for remote access to the target machine. In a previous paper, we have shown how Backdoors can be used for recovery of "good" OS and application state from a failed system on other healthy systems.

In this paper, we describe how Backdoors can be used to detect and repair damage to the OS state of a computer system. We present two case studies of remote repair of an OS subject to resource depletion (fork bomb and memory hog) to the point where it cannot perform useful work and local repair is impossible. We show that our prototype detects OS resource exhaustion ef.ciently and it successfully repairs the affected system.