diff --git a/decnet/cli.py b/decnet/cli.py
index 8cc83e6..0e503e6 100644
--- a/decnet/cli.py
+++ b/decnet/cli.py
@@ -120,8 +120,6 @@ def deploy(
     config_file: Optional[str] = typer.Option(None, "--config", "-c", help="Path to INI config file"),
     api: bool = typer.Option(False, "--api", help="Start the FastAPI backend to ingest and serve logs"),
     api_port: int = typer.Option(8000, "--api-port", help="Port for the backend API"),
-    probe_targets: Optional[str] = typer.Option(None, "--probe-targets", help="Comma-separated ip:port pairs for JARM active probing (e.g. 10.0.0.1:443,10.0.0.2:8443)"),
-    probe_interval: int = typer.Option(300, "--probe-interval", help="Seconds between JARM probe cycles (default: 300)"),
 ) -> None:
     """Deploy deckies to the LAN."""
     import os
@@ -298,18 +296,16 @@ def deploy(
         except (FileNotFoundError, subprocess.SubprocessError):
             console.print("[red]Failed to start API. Ensure 'uvicorn' is installed in the current environment.[/]")
 
-    if probe_targets and not dry_run:
+    if effective_log_file and not dry_run:
         import subprocess  # nosec B404
         import sys
-        console.print(f"[bold cyan]Starting DECNET-PROBER[/] → targets: {probe_targets}")
+        console.print("[bold cyan]Starting DECNET-PROBER[/] (auto-discovers attackers from log stream)")
         try:
             _prober_args = [
                 sys.executable, "-m", "decnet.cli", "probe",
-                "--targets", probe_targets,
-                "--interval", str(probe_interval),
+                "--daemon",
+                "--log-file", str(effective_log_file),
             ]
-            if effective_log_file:
-                _prober_args.extend(["--log-file", str(effective_log_file)])
             subprocess.Popen(  # nosec B603
                 _prober_args,
                 stdin=subprocess.DEVNULL,
@@ -323,17 +319,28 @@ def deploy(
 
 @app.command()
 def probe(
-    targets: str = typer.Option(..., "--targets", "-t", help="Comma-separated ip:port pairs to JARM fingerprint"),
-    log_file: str = typer.Option(DECNET_INGEST_LOG_FILE, "--log-file", "-f", help="Path for RFC 5424 syslog + .json output"),
+    log_file: str = typer.Option(DECNET_INGEST_LOG_FILE, "--log-file", "-f", help="Path for RFC 5424 syslog + .json output (reads attackers from .json, writes results to both)"),
     interval: int = typer.Option(300, "--interval", "-i", help="Seconds between probe cycles (default: 300)"),
     timeout: float = typer.Option(5.0, "--timeout", help="Per-probe TCP timeout in seconds"),
+    daemon: bool = typer.Option(False, "--daemon", "-d", help="Detach to background (used by deploy, no console output)"),
 ) -> None:
-    """Run JARM active fingerprinting against target hosts."""
+    """JARM-fingerprint all attackers discovered in the log stream."""
     import asyncio
     from decnet.prober import prober_worker
-    log.info("probe command invoked targets=%s interval=%d", targets, interval)
-    console.print(f"[bold cyan]DECNET-PROBER starting[/] → {targets}")
-    asyncio.run(prober_worker(log_file, targets, interval=interval, timeout=timeout))
+
+    if daemon:
+        # Suppress console output when running as background daemon
+        import os
+        log.info("probe daemon starting log_file=%s interval=%d", log_file, interval)
+        asyncio.run(prober_worker(log_file, interval=interval, timeout=timeout))
+    else:
+        log.info("probe command invoked log_file=%s interval=%d", log_file, interval)
+        console.print(f"[bold cyan]DECNET-PROBER[/] watching {log_file} for attackers (interval: {interval}s)")
+        console.print("[dim]Press Ctrl+C to stop[/]")
+        try:
+            asyncio.run(prober_worker(log_file, interval=interval, timeout=timeout))
+        except KeyboardInterrupt:
+            console.print("\n[yellow]DECNET-PROBER stopped.[/]")
 
 
 @app.command()
diff --git a/decnet/prober/worker.py b/decnet/prober/worker.py
index 74c6795..ba133cb 100644
--- a/decnet/prober/worker.py
+++ b/decnet/prober/worker.py
@@ -1,10 +1,12 @@
 """
 DECNET-PROBER standalone worker.
 
-Runs as a detached host-level process. Probes targets on a configurable
-interval and writes results as RFC 5424 syslog + JSON to the same log
-files the collector uses. The ingester tails the JSON file and extracts
-JARM bounties automatically.
+Runs as a detached host-level process. Discovers attacker IPs by tailing the
+collector's JSON log file, then JARM-probes them on common C2/TLS ports.
+Results are written as RFC 5424 syslog + JSON to the same log files.
+
+Target discovery is fully automatic — every unique attacker IP seen in the
+log stream gets probed. No manual target list required.
 
 Tech debt: writing directly to the collector's log files couples the
 prober to the collector's file format. A future refactor should introduce
@@ -21,10 +23,17 @@ from pathlib import Path
 from typing import Any
 
 from decnet.logging import get_logger
-from decnet.prober.jarm import jarm_hash
+from decnet.prober.jarm import JARM_EMPTY_HASH, jarm_hash
 
 logger = get_logger("prober")
 
+# ─── Default ports to JARM-probe on each attacker IP ─────────────────────────
+# Common C2 callback / TLS server ports (Cobalt Strike, Sliver, Metasploit, etc.)
+
+DEFAULT_PROBE_PORTS: list[int] = [
+    443, 8443, 8080, 4443, 50050, 2222, 993, 995, 8888, 9001,
+]
+
 # ─── RFC 5424 formatting (inline, mirrors templates/*/decnet_logging.py) ─────
 
 _FACILITY_LOCAL0 = 16
@@ -144,100 +153,181 @@ def _write_event(
             f.flush()
 
 
-# ─── Target parser ───────────────────────────────────────────────────────────
+# ─── Target discovery from log stream ────────────────────────────────────────
 
-def _parse_targets(raw: str) -> list[tuple[str, int]]:
-    """Parse 'ip:port,ip:port,...' into a list of (host, port) tuples."""
-    targets: list[tuple[str, int]] = []
-    for entry in raw.split(","):
-        entry = entry.strip()
-        if not entry:
-            continue
-        if ":" not in entry:
-            logger.warning("prober: skipping malformed target %r (missing port)", entry)
-            continue
-        host, _, port_str = entry.rpartition(":")
-        try:
-            port = int(port_str)
-            if not (1 <= port <= 65535):
-                raise ValueError
-            targets.append((host, port))
-        except ValueError:
-            logger.warning("prober: skipping malformed target %r (bad port)", entry)
-    return targets
+def _discover_attackers(json_path: Path, position: int) -> tuple[set[str], int]:
+    """
+    Read new JSON log lines from the given position and extract unique
+    attacker IPs. Returns (new_ips, new_position).
+
+    Only considers IPs that are not "Unknown" and come from events that
+    indicate real attacker interaction (not prober's own events).
+    """
+    new_ips: set[str] = set()
+
+    if not json_path.exists():
+        return new_ips, position
+
+    size = json_path.stat().st_size
+    if size < position:
+        position = 0  # file rotated
+
+    if size == position:
+        return new_ips, position
+
+    with open(json_path, "r", encoding="utf-8", errors="replace") as f:
+        f.seek(position)
+        while True:
+            line = f.readline()
+            if not line:
+                break
+            if not line.endswith("\n"):
+                break  # partial line
+
+            try:
+                record = json.loads(line.strip())
+            except json.JSONDecodeError:
+                position = f.tell()
+                continue
+
+            # Skip our own events
+            if record.get("service") == "prober":
+                position = f.tell()
+                continue
+
+            ip = record.get("attacker_ip", "Unknown")
+            if ip != "Unknown" and ip:
+                new_ips.add(ip)
+
+            position = f.tell()
+
+    return new_ips, position
 
 
 # ─── Probe cycle ─────────────────────────────────────────────────────────────
 
 def _probe_cycle(
-    targets: list[tuple[str, int]],
+    targets: set[str],
+    probed: dict[str, set[int]],
+    ports: list[int],
     log_path: Path,
     json_path: Path,
     timeout: float = 5.0,
 ) -> None:
-    for host, port in targets:
-        try:
-            h = jarm_hash(host, port, timeout=timeout)
-            _write_event(
-                log_path, json_path,
-                "jarm_fingerprint",
-                target_ip=host,
-                target_port=str(port),
-                jarm_hash=h,
-                msg=f"JARM {host}:{port} = {h}",
-            )
-            logger.info("prober: JARM %s:%d = %s", host, port, h)
-        except Exception as exc:
-            _write_event(
-                log_path, json_path,
-                "prober_error",
-                severity=_SEVERITY_WARNING,
-                target_ip=host,
-                target_port=str(port),
-                error=str(exc),
-                msg=f"JARM probe failed for {host}:{port}: {exc}",
-            )
-            logger.warning("prober: JARM probe failed %s:%d: %s", host, port, exc)
+    """
+    Probe all known attacker IPs on the configured ports.
+
+    Args:
+        targets: set of attacker IPs to probe
+        probed: dict mapping IP -> set of ports already successfully probed
+        ports: list of ports to probe on each IP
+        log_path: RFC 5424 log file
+        json_path: JSON log file
+        timeout: per-probe TCP timeout
+    """
+    for ip in sorted(targets):
+        already_done = probed.get(ip, set())
+        ports_to_probe = [p for p in ports if p not in already_done]
+
+        if not ports_to_probe:
+            continue
+
+        for port in ports_to_probe:
+            try:
+                h = jarm_hash(ip, port, timeout=timeout)
+                if h == JARM_EMPTY_HASH:
+                    # No TLS server on this port — don't log, don't reprobed
+                    probed.setdefault(ip, set()).add(port)
+                    continue
+
+                _write_event(
+                    log_path, json_path,
+                    "jarm_fingerprint",
+                    target_ip=ip,
+                    target_port=str(port),
+                    jarm_hash=h,
+                    msg=f"JARM {ip}:{port} = {h}",
+                )
+                logger.info("prober: JARM %s:%d = %s", ip, port, h)
+                probed.setdefault(ip, set()).add(port)
+
+            except Exception as exc:
+                _write_event(
+                    log_path, json_path,
+                    "prober_error",
+                    severity=_SEVERITY_WARNING,
+                    target_ip=ip,
+                    target_port=str(port),
+                    error=str(exc),
+                    msg=f"JARM probe failed for {ip}:{port}: {exc}",
+                )
+                logger.warning("prober: JARM probe failed %s:%d: %s", ip, port, exc)
+                # Mark as probed to avoid infinite retries
+                probed.setdefault(ip, set()).add(port)
 
 
 # ─── Main worker ─────────────────────────────────────────────────────────────
 
 async def prober_worker(
     log_file: str,
-    targets_raw: str,
     interval: int = 300,
     timeout: float = 5.0,
+    ports: list[int] | None = None,
 ) -> None:
     """
     Main entry point for the standalone prober process.
 
+    Discovers attacker IPs automatically by tailing the JSON log file,
+    then JARM-probes each IP on common C2 ports.
+
     Args:
         log_file: base path for log files (RFC 5424 to .log, JSON to .json)
-        targets_raw: comma-separated ip:port pairs
         interval: seconds between probe cycles
         timeout: per-probe TCP timeout
+        ports: list of ports to probe (defaults to DEFAULT_PROBE_PORTS)
     """
-    targets = _parse_targets(targets_raw)
-    if not targets:
-        logger.error("prober: no valid targets, exiting")
-        return
+    probe_ports = ports or DEFAULT_PROBE_PORTS
 
     log_path = Path(log_file)
     json_path = log_path.with_suffix(".json")
     log_path.parent.mkdir(parents=True, exist_ok=True)
 
-    logger.info("prober started targets=%d interval=%ds log=%s", len(targets), interval, log_path)
+    logger.info(
+        "prober started interval=%ds ports=%s log=%s",
+        interval, ",".join(str(p) for p in probe_ports), log_path,
+    )
 
     _write_event(
         log_path, json_path,
         "prober_startup",
-        target_count=str(len(targets)),
         interval=str(interval),
-        msg=f"DECNET-PROBER started with {len(targets)} targets, interval {interval}s",
+        probe_ports=",".join(str(p) for p in probe_ports),
+        msg=f"DECNET-PROBER started, interval {interval}s, "
+            f"ports {','.join(str(p) for p in probe_ports)}",
     )
 
+    known_attackers: set[str] = set()
+    probed: dict[str, set[int]] = {}  # IP -> set of ports already probed
+    log_position: int = 0
+
     while True:
-        await asyncio.to_thread(
-            _probe_cycle, targets, log_path, json_path, timeout,
+        # Discover new attacker IPs from the log stream
+        new_ips, log_position = await asyncio.to_thread(
+            _discover_attackers, json_path, log_position,
         )
+
+        if new_ips - known_attackers:
+            fresh = new_ips - known_attackers
+            known_attackers.update(fresh)
+            logger.info(
+                "prober: discovered %d new attacker(s), total=%d",
+                len(fresh), len(known_attackers),
+            )
+
+        if known_attackers:
+            await asyncio.to_thread(
+                _probe_cycle, known_attackers, probed, probe_ports,
+                log_path, json_path, timeout,
+            )
+
         await asyncio.sleep(interval)
diff --git a/tests/test_prober_jarm.py b/tests/test_prober_jarm.py
index 67bf8ed..d0f8fd1 100644
--- a/tests/test_prober_jarm.py
+++ b/tests/test_prober_jarm.py
@@ -60,15 +60,6 @@ class TestBuildClientHello:
             # supported_versions extension type = 0x002B
             assert b"\x00\x2b" in data, f"Probe {idx} missing supported_versions"
 
-    def test_non_tls13_probes_lack_supported_versions(self):
-        """Probes 0, 1, 2, 7, 8 should NOT include supported_versions."""
-        for idx in (0, 1, 2, 7, 8):
-            data = _build_client_hello(idx, host="example.com")
-            # Check that 0x002B doesn't appear as extension type
-            # We need to be more careful here — just check it's not in extensions area
-            # After session_id, ciphers, compression comes extensions
-            assert data[0] == 0x16  # sanity
-
     def test_probe_9_includes_alpn_http11(self):
         data = _build_client_hello(9, host="example.com")
         assert b"http/1.1" in data
@@ -129,7 +120,6 @@ class TestParseServerHello:
 
     def test_tls13_via_supported_versions(self):
         """When supported_versions extension says TLS 1.3, version should be tls13."""
-        # supported_versions extension: type=0x002B, length=2, version=0x0304
         ext = struct.pack("!HHH", 0x002B, 2, 0x0304)
         data = _make_server_hello(cipher=0x1301, version=0x0303, extensions=ext)
         result = _parse_server_hello(data)
@@ -153,7 +143,6 @@ class TestParseServerHello:
 
     def test_non_server_hello_returns_separator(self):
         """A Certificate message (type 0x0B) should not parse as ServerHello."""
-        # Build a record that's handshake type but has wrong hs type
         body = b"\x00" * 40
         hs = struct.pack("B", 0x0B) + struct.pack("!I", len(body))[1:] + body
         record = struct.pack("B", 0x16) + struct.pack("!H", 0x0303) + struct.pack("!H", len(hs)) + hs
diff --git a/tests/test_prober_worker.py b/tests/test_prober_worker.py
new file mode 100644
index 0000000..208907a
--- /dev/null
+++ b/tests/test_prober_worker.py
@@ -0,0 +1,207 @@
+"""
+Tests for the prober worker — target discovery from the log stream and
+probe cycle behavior.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from decnet.prober.jarm import JARM_EMPTY_HASH
+from decnet.prober.worker import (
+    DEFAULT_PROBE_PORTS,
+    _discover_attackers,
+    _probe_cycle,
+    _write_event,
+)
+
+
+# ─── _discover_attackers ─────────────────────────────────────────────────────
+
+class TestDiscoverAttackers:
+
+    def test_discovers_unique_ips(self, tmp_path: Path):
+        json_file = tmp_path / "decnet.json"
+        records = [
+            {"service": "sniffer", "event_type": "tls_client_hello", "attacker_ip": "10.0.0.1", "fields": {}},
+            {"service": "ssh", "event_type": "login_attempt", "attacker_ip": "10.0.0.2", "fields": {}},
+            {"service": "sniffer", "event_type": "tls_client_hello", "attacker_ip": "10.0.0.1", "fields": {}},  # dup
+        ]
+        json_file.write_text("\n".join(json.dumps(r) for r in records) + "\n")
+
+        ips, pos = _discover_attackers(json_file, 0)
+        assert ips == {"10.0.0.1", "10.0.0.2"}
+        assert pos > 0
+
+    def test_skips_prober_events(self, tmp_path: Path):
+        json_file = tmp_path / "decnet.json"
+        records = [
+            {"service": "prober", "event_type": "jarm_fingerprint", "attacker_ip": "10.0.0.99", "fields": {}},
+            {"service": "ssh", "event_type": "login_attempt", "attacker_ip": "10.0.0.1", "fields": {}},
+        ]
+        json_file.write_text("\n".join(json.dumps(r) for r in records) + "\n")
+
+        ips, _ = _discover_attackers(json_file, 0)
+        assert "10.0.0.99" not in ips
+        assert "10.0.0.1" in ips
+
+    def test_skips_unknown_ips(self, tmp_path: Path):
+        json_file = tmp_path / "decnet.json"
+        records = [
+            {"service": "sniffer", "event_type": "startup", "attacker_ip": "Unknown", "fields": {}},
+        ]
+        json_file.write_text("\n".join(json.dumps(r) for r in records) + "\n")
+
+        ips, _ = _discover_attackers(json_file, 0)
+        assert len(ips) == 0
+
+    def test_handles_missing_file(self, tmp_path: Path):
+        json_file = tmp_path / "nonexistent.json"
+        ips, pos = _discover_attackers(json_file, 0)
+        assert len(ips) == 0
+        assert pos == 0
+
+    def test_resumes_from_position(self, tmp_path: Path):
+        json_file = tmp_path / "decnet.json"
+        line1 = json.dumps({"service": "ssh", "attacker_ip": "10.0.0.1", "fields": {}}) + "\n"
+        json_file.write_text(line1)
+
+        _, pos1 = _discover_attackers(json_file, 0)
+
+        # Append more
+        with open(json_file, "a") as f:
+            f.write(json.dumps({"service": "ssh", "attacker_ip": "10.0.0.2", "fields": {}}) + "\n")
+
+        ips, pos2 = _discover_attackers(json_file, pos1)
+        assert ips == {"10.0.0.2"}  # only the new one
+        assert pos2 > pos1
+
+    def test_handles_file_rotation(self, tmp_path: Path):
+        json_file = tmp_path / "decnet.json"
+        # Write enough data to push position well ahead
+        lines = [json.dumps({"service": "ssh", "attacker_ip": f"10.0.0.{i}", "fields": {}}) + "\n" for i in range(10)]
+        json_file.write_text("".join(lines))
+        _, pos = _discover_attackers(json_file, 0)
+        assert pos > 0
+
+        # Simulate rotation — new file is smaller than the old position
+        json_file.write_text(json.dumps({"service": "ssh", "attacker_ip": "10.0.0.99", "fields": {}}) + "\n")
+        assert json_file.stat().st_size < pos
+
+        ips, new_pos = _discover_attackers(json_file, pos)
+        assert "10.0.0.99" in ips
+
+    def test_handles_malformed_json(self, tmp_path: Path):
+        json_file = tmp_path / "decnet.json"
+        json_file.write_text("not valid json\n" + json.dumps({"service": "ssh", "attacker_ip": "10.0.0.1", "fields": {}}) + "\n")
+
+        ips, _ = _discover_attackers(json_file, 0)
+        assert "10.0.0.1" in ips
+
+
+# ─── _probe_cycle ────────────────────────────────────────────────────────────
+
+class TestProbeCycle:
+
+    @patch("decnet.prober.worker.jarm_hash")
+    def test_probes_new_ips(self, mock_jarm: MagicMock, tmp_path: Path):
+        mock_jarm.return_value = "c0c" * 10 + "a" * 32  # fake 62-char hash
+        log_path = tmp_path / "decnet.log"
+        json_path = tmp_path / "decnet.json"
+
+        targets = {"10.0.0.1"}
+        probed: dict[str, set[int]] = {}
+
+        _probe_cycle(targets, probed, [443, 8443], log_path, json_path, timeout=1.0)
+
+        assert mock_jarm.call_count == 2  # two ports
+        assert 443 in probed["10.0.0.1"]
+        assert 8443 in probed["10.0.0.1"]
+
+    @patch("decnet.prober.worker.jarm_hash")
+    def test_skips_already_probed_ports(self, mock_jarm: MagicMock, tmp_path: Path):
+        mock_jarm.return_value = "c0c" * 10 + "a" * 32
+        log_path = tmp_path / "decnet.log"
+        json_path = tmp_path / "decnet.json"
+
+        targets = {"10.0.0.1"}
+        probed: dict[str, set[int]] = {"10.0.0.1": {443}}
+
+        _probe_cycle(targets, probed, [443, 8443], log_path, json_path, timeout=1.0)
+
+        # Should only probe 8443 (443 already done)
+        assert mock_jarm.call_count == 1
+        mock_jarm.assert_called_once_with("10.0.0.1", 8443, timeout=1.0)
+
+    @patch("decnet.prober.worker.jarm_hash")
+    def test_empty_hash_not_logged(self, mock_jarm: MagicMock, tmp_path: Path):
+        """All-zeros JARM hash (no TLS server) should not be written as a jarm_fingerprint event."""
+        mock_jarm.return_value = JARM_EMPTY_HASH
+        log_path = tmp_path / "decnet.log"
+        json_path = tmp_path / "decnet.json"
+
+        targets = {"10.0.0.1"}
+        probed: dict[str, set[int]] = {}
+
+        _probe_cycle(targets, probed, [443], log_path, json_path, timeout=1.0)
+
+        # Port should be marked as probed
+        assert 443 in probed["10.0.0.1"]
+        # But no jarm_fingerprint event should be written
+        if json_path.exists():
+            content = json_path.read_text()
+            assert "jarm_fingerprint" not in content
+
+    @patch("decnet.prober.worker.jarm_hash")
+    def test_exception_marks_port_probed(self, mock_jarm: MagicMock, tmp_path: Path):
+        mock_jarm.side_effect = OSError("Connection refused")
+        log_path = tmp_path / "decnet.log"
+        json_path = tmp_path / "decnet.json"
+
+        targets = {"10.0.0.1"}
+        probed: dict[str, set[int]] = {}
+
+        _probe_cycle(targets, probed, [443], log_path, json_path, timeout=1.0)
+
+        # Port marked as probed to avoid infinite retries
+        assert 443 in probed["10.0.0.1"]
+
+    @patch("decnet.prober.worker.jarm_hash")
+    def test_skips_ip_with_all_ports_done(self, mock_jarm: MagicMock, tmp_path: Path):
+        log_path = tmp_path / "decnet.log"
+        json_path = tmp_path / "decnet.json"
+
+        targets = {"10.0.0.1"}
+        probed: dict[str, set[int]] = {"10.0.0.1": {443, 8443}}
+
+        _probe_cycle(targets, probed, [443, 8443], log_path, json_path, timeout=1.0)
+
+        assert mock_jarm.call_count == 0
+
+
+# ─── _write_event ────────────────────────────────────────────────────────────
+
+class TestWriteEvent:
+
+    def test_writes_rfc5424_and_json(self, tmp_path: Path):
+        log_path = tmp_path / "decnet.log"
+        json_path = tmp_path / "decnet.json"
+
+        _write_event(log_path, json_path, "test_event", target_ip="10.0.0.1", msg="test")
+
+        assert log_path.exists()
+        assert json_path.exists()
+
+        log_content = log_path.read_text()
+        assert "test_event" in log_content
+        assert "decnet@55555" in log_content
+
+        json_content = json_path.read_text()
+        record = json.loads(json_content.strip())
+        assert record["event_type"] == "test_event"
+        assert record["service"] == "prober"
+        assert record["fields"]["target_ip"] == "10.0.0.1"