No Egress, No Shell, No Problem

This report introduces a lightweight C-based daemon, shellnot, designed to maintain a persistent pseudo-interactive shell using forkpty and a UNIX domain socket to send input and retrieve buffered output, enabling practical interaction on hosts where only RCE is available and outbound connectivity is restricted; it outlines base64-based file transfer, compilation and background execution steps, session handling by ID, and demonstrates usage, with a link to the project repository.