Show HN: Z-Jail – A 130 KB Linux sandbox-C99 with 7 defense layers and zero deps

Z-Jail is a lightweight Linux sandbox (~81 KB) that provides seven ordered isolation layers for executing untrusted native code, including namespaces, pivot_root, capability dropping, NO_NEW_PRIVS, seccomp-BPF syscall filtering, and audit logging—all with zero external dependencies. It fills a niche between minimal tools like bwrap and heavier solutions like nsjail, targeting use cases such as CI pipelines, CTF challenges, and code evaluation where defense-in-depth is needed without container runtime overhead.