netwatch | NetWatch System Management Mode VNC Server

netwatch is a C library. netwatch has no bugs, it has no vulnerabilities and it has low support. However netwatch has a Non-SPDX License. You can download it from GitHub.

this is netwatch, a system for remote system-management-mode-based control of a machine without support from or awareness by the os. it works by taking over a second network card to provide a standard vnc server, such that a machine elsewhere on the network can see the text or graphics console of the machine and inject keystrokes as needed. system management mode, introduced with the 386sl, essentially allows system driver code to run outside of os control, caused by a special interrupt pin on the cpu. this was originally intended for applications such as laptop fan control; it is also the mechanism by which usb legacy keyboard emulation occurs. when a system management interrupt occurs, the northbridge remaps portions of memory to expose previously-hidden code, and asserts an smi# signal, causing the cpu to save all its state into system management ram and vector to a magic entry point. this is somewhat slow, and so there is a moderate performance impact caused by running netwatch, more significant when a vnc session is open. because netwatch is invisible to the os, its cpu usage is difficult to monitor; we do so by comparing the md5 throughput of the system with netwatch running versus