Enodia Sentinel v0.1 — bash host-IDS prototype

Poll-based host intrusion-detection daemon modeled on freeze-watcher's
sample→trigger→snapshot→classify loop, with security signatures instead
of performance ones:

- reverse_shell  (interpreter with a network socket on stdio)
- ld_preload     (/etc/ld.so.preload or LD_PRELOAD in writable dirs)
- deleted_exe    (process running from a deleted/memfd binary)
- new_listener   (listening port absent from startup baseline)
- new_suid       (new SUID/SGID binary; critical in writable dirs)
- persistence    (cron/systemd/authorized_keys/rc-file changes)
- suspicious_egress (interpreter holding an outbound public connection)

Each capture writes a forensic snapshot with per-signature incident-
response guidance. Includes a safe, self-cleaning red-team harness
(sentinel-redteam), hardened systemd unit, config, Makefile, and Arch
packaging.

Tested on Arch: detectors fire on drills, no false positives on a clean
sweep, sweep cost optimized from ~15s to ~1s via batched syscalls and a
gated filesystem-wide SUID scan.

This bash implementation is retained as the regression oracle for the
forthcoming Python rewrite.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packaging/PKGBUILD

@@ -0,0 +1,24 @@
+# Maintainer: Enodia
+pkgname=enodia-sentinel
+pkgver=0.1.0
+pkgrel=1
+pkgdesc="Host intrusion-detection daemon — signature-based detection of reverse shells, LD_PRELOAD rootkits, fileless malware, and persistence tampering"
+arch=('any')
+url="https://github.com/Enodia/enodia-sentinel"
+license=('MIT')
+depends=('bash' 'iproute2' 'procps-ng')
+optdepends=('bpftrace: execve tracing of short-lived processes in snapshots'
+            'libnotify: desktop notifications on alert')
+backup=('etc/enodia-sentinel.conf')
+source=()
+sha256sums=()
+
+package() {
+    cd "$startdir/.."
+    install -Dm755 src/sentinel.sh      "$pkgdir/usr/bin/sentinel.sh"
+    install -Dm755 src/sentinel-redteam "$pkgdir/usr/bin/sentinel-redteam"
+    install -Dm644 systemd/enodia-sentinel.service "$pkgdir/usr/lib/systemd/system/enodia-sentinel.service"
+    install -Dm644 config/enodia-sentinel.conf "$pkgdir/etc/enodia-sentinel.conf"
+    install -Dm644 LICENSE "$pkgdir/usr/share/licenses/$pkgname/LICENSE"
+    install -dm750 "$pkgdir/var/log/enodia-sentinel"
+}