# Enodia Sentinel Go Agent (Migration Sidecar)

This directory is the parallel Go implementation described in
`docs/SURICATA_ASSIMILATION.md`. Python remains the production agent and the
behavioral oracle until every subsystem reaches fixture and red-team parity.

Current scope:

- standard-library-only flat TOML loading for the settings used so far;
- an injectable `/proc` process/file-descriptor/memory-map snapshot plus
  fail-open `ss` socket collection;
- a cancellable sweep loop that emits JSONL `enodia.event.v1` records;
- exact `enodia.alert.v1` parity for `ld_preload` (SID `100011`),
  `deleted_exe` (`100012`), `input_snooper` (`100032`), and
  `credential_access` (`100033`), plus `reverse_shell` (`100010`), `egress`
  (`100016`), `stealth_network` (`100036`), and the `/proc/<pid>/maps`
  `memory_obfuscation` cohort (`100039`, `100048`, `100049`), and
  `first_seen` (`100074`, `100075`), `new_listener` (`100013`),
  `persistence` (`100015`), and `new_suid` (`100014`);
- an opt-in live baseline lifecycle (`--state-dir`) that builds listener/SUID
  baselines, honors the startup grace gate, scans persistence paths, and
  atomically retains `first-seen.json` using the Python-compatible schema;
- pure exec and syscall event models plus replayable rule engines: built-in
  exec SIDs `100001`–`100004`, configured `[[exec_rules]]`, and syscall SIDs
  `100060`–`100066` now emit Python-identical alert envelopes without requiring
  a kernel probe;
- typed host-event SIDs `100067`–`100073` and `100076`–`100078`, a unified
  mixed JSONL pipeline, Python-compatible `rules-list`/`rules-show` metadata,
  correlation SID `100080`, and a shared per-key cooldown gate;
- opt-in native exec (`--ebpf-exec`) and security-syscall (`--ebpf-syscall`)
  tracepoint sources built with `cilium/ebpf` v0.22.0 and CO-RE parent-process
  lookup. They feed the same rule/cooldown/envelope paths as replay and degrade
  to polling when loading, attaching, or reading is unavailable. The syscall
  probe filters its security-relevant syscall numbers in-kernel and also routes
  `setuid`/`setgid` into typed host-event SIDs `100071`/`100072`, plus
  `chmod`/`chown` variants into SID `100070`, `capset` into SID `100077`, and
  `finit_module` into SID `100078` after resolving the module FD path. Confirmed
  interpreter `write`, `writev`, `pwrite64`, `pwritev`, and `pwritev2` calls are
  enter/exit-correlated for SID `100069`.
  Successful IPv4/IPv6 `connect`, `bind`, `listen`, and `accept` calls feed SIDs
  `100067`, `100073`, `100068`, and `100076`;
- `enodia.status.v1` heartbeat records whose alert totals, severity counts, and
  last-alert time are derived from the retained Go snapshot store;
- optional bounded JSONL retention (`--event-log`) with private permissions,
  one rotated segment, and synchronous flushes for non-status records;
- optional `enodia.alert.snapshot.v1` JSON/text pairs (`--snapshot-dir`) with
  same-second alert batching, best-effort `/proc` context, and Python-compatible
  count/age pruning;
- Python-compatible `enodia.incident.v1` grouping and atomic `incidents.json`
  persistence, using process lineage first and the shared time-window fallback,
  including additive SID `100080` correlation evidence;
- a shared fixture checked against the Python detector by
  `scripts/check-go-parity.py`.

It does not yet provide Python's rich enrichment, assurance chain, notification
fan-out, or management consumers for those snapshots, and it does not replace
`enodia-sentinel`. The module requires Go 1.25 or newer; development is currently
verified with Go 1.26.5. Run a single terminal-visible stateless sweep:

```bash
cd go-agent
GOCACHE=/tmp/enodia-go-cache go run ./cmd/enodia-sentinel-go --once
```

Print the packaged agent identity with `enodia-sentinel-go --version`.

Exercise the live baseline lifecycle in an isolated directory (do not point the
migration sidecar at the production Python agent's state directory):

```bash
GOCACHE=/tmp/enodia-go-cache go run ./cmd/enodia-sentinel-go \
  --state-dir /tmp/enodia-sentinel-go-state
```

Development verification from the repository root:

```bash
make generate-go  # only after editing internal/ebpfsource/bpf/*.bpf.c
make test-go
make parity-go
```

Build and install the opt-in production validation sidecar from the repository
root:

```bash
make build-go
sudo make install-go
sudo make enable-go
make status-go
make logs-go
```

`enodia-sentinel-go-sidecar.service` writes JSONL to the system journal and
keeps baseline lifecycle files under `/var/lib/enodia-sentinel-go`. It also
retains the same envelopes in `events.jsonl`, rotating to `events.jsonl.1`
before the active file exceeds 64 MiB. Both files are mode `0600`; alert and
incident records are synchronized before emission succeeds, while routine
status records use normal kernel writeback. It never shares the Python daemon's
`/var/log/enodia-sentinel` state. Both native probes are requested by the unit;
a probe load failure is visible in status events and the polling loop remains
active. Installing the sidecar does not enable it or alter
`enodia-sentinel.service`. The unit reaches `active` only after baseline
initialization, event-log and snapshot-store preflight, and both requested probe
load attempts finish.

Alert envelopes are also batched into private
`alert-YYYYMMDD-HHMMSS.{json,log}` pairs under the same isolated directory.
The JSON side implements the required `enodia.alert.snapshot.v1` fields and the
service applies shared `max_snapshots` / `max_snapshot_age_days` limits. Status
counts are populated only from parseable retained snapshots. Each snapshot is
linked to an incident in a private atomic `incidents.json` index. Grouping uses
the configured `incident_tracking`, `incident_window`, and
`incident_lineage_depth` settings; same-second alert batches update one incident
and one snapshot name idempotently. Enrichment is currently limited to a
Go-source marker plus best-effort process detail; the Python forensic
enrichment/assurance and notification pipelines remain future parity work.

After every successfully emitted status record, the service atomically updates
`/var/lib/enodia-sentinel-go/heartbeat` with the current Unix timestamp (mode
`0600`). The file remains after shutdown so external watchdogs can identify a
stale sensor.

Check that signal with JSON output and a watchdog-friendly exit status:

```bash
enodia-sentinel-go --health
# For an isolated development run:
enodia-sentinel-go --health --state-dir /tmp/enodia-sentinel-go-state
```

The command uses `heartbeat_max_age` from the shared configuration, defaults to
the service state path when `--state-dir` is omitted, and exits nonzero for a
missing, malformed, or stale heartbeat.

For an ad-hoc retained run, set an explicit path and byte bound:

```bash
enodia-sentinel-go --state-dir /tmp/enodia-go-state \
  --event-log /tmp/enodia-go-state/events.jsonl \
  --event-log-max-bytes 8388608
```

Inspect recent retained records across both the active and rotated segments:

```bash
sudo enodia-sentinel-go --events-tail 50
# Or inspect an ad-hoc state tree:
enodia-sentinel-go --events-tail 50 --state-dir /tmp/enodia-go-state
```

The reader returns chronological JSONL, validates every source record, and
fails nonzero rather than forwarding corrupted evidence. It does not load the
agent configuration, so retained evidence remains available while a broken
configuration prevents the service from starting.

`--fixture`, `--host`, `--timestamp`, `--proc-root`, and `--suid-root` exist for
deterministic parity/testing. Fixture mode never activates the live baseline
manager. Production work should continue to use the default live `/proc`,
hostname, and local timestamp.

The kernel sources are explicitly opt-in while this remains a sidecar. They
require the privileges needed to load BPF programs and create maps. A load
failure is reported on stderr and in `enodia.status.v1`, then the poll loop
continues:

```bash
sudo go run ./cmd/enodia-sentinel-go --ebpf-exec --ebpf-syscall
```

Offline event-rule replays remain available without BPF or root:

```bash
go run ./cmd/enodia-sentinel-go --exec-events ../tests/fixtures/go/exec-events.json
go run ./cmd/enodia-sentinel-go --syscall-events ../tests/fixtures/go/syscall-events.json
go run ./cmd/enodia-sentinel-go --host-events ../tests/fixtures/go/host-events.json
go run ./cmd/enodia-sentinel-go --event-stream ../tests/fixtures/go/mixed-events.jsonl
go run ./cmd/enodia-sentinel-go --rules-list
```