sentinel: log subprocess failures + AI-busy retry/callback + allowlist all ban-paths

Three issues from J 2026-04-30:

1. Silent fail2ban-client / nginx subprocess failures
   Pre-fix _execute_ban called fail2ban-client with capture_output=True
   but threw away the result. _nginx_ban had bare `except: pass`
   swallowing everything. So a non-zero fail2ban exit (jail not
   configured, IP already banned, IPv6 quirk) or PermissionError
   on /etc/nginx/banned_ips.conf logged "AI_BAN" while the attacker
   walked through unimpeded. The "errors in logs" J was seeing.

   Now every subprocess failure surfaces:
   - FAIL2BAN_FAILED rc=N stderr=... — non-zero exit
   - FAIL2BAN_TIMEOUT — client didn't return in 5s
   - FAIL2BAN_NOT_INSTALLED — binary missing
   - NGINX_BAN_WRITE_DENIED — permission error on conf file
   - NGINX_RELOAD_FAILED rc=N stderr=... — systemctl reload non-zero
   - NGINX_RELOAD_TIMEOUT / NGINX_RELOAD_NO_SYSTEMCTL — runtime gaps
   sec_log.error catches these so journalctl -u llm-team-ui shows
   the actual reason a ban didn't stick.

2. AI auto-scan failure callback when model is busy
   Pre-fix Ollama unreachable / busy / timeout silently preserved
   log position + skipped the scan. Operator only learned about
   the gap by manually checking sentinel-status. Now:
   - 1 retry inside same scan after SENTINEL_AI_RETRY_DELAY_SECS
     (30s) on connection error / timeout / 429 / 503
   - 4xx errors that won't recover (404 model missing, 400 bad
     prompt) fail fast without retrying
   - consecutive_ai_failures counter in _sentinel_stats
   - On 3+ consecutive failures, send_security_alert() fires —
     "Sentinel AI unreachable" email with last error + endpoint
     + model name. One alert per outage (ai_busy_alerted flag);
     clears on first successful scan so flapping doesn't spam.
   - AI_RECOVERED log line on first scan after a streak.

3. Sentinel ban path still substring-matched 192.168
   Same vulnerability class as admin_ban_ip had — only protected
   one /16. Replaced 4 sites with is_allowlisted(ip):
   - threat-list display filter (line 7638): now hides ALL
     allowlisted IPs from the panel
   - mass-ban API (line 8016): refuses ban for any allowlisted IP
   - sentinel analysis filter (line 12786): saves AI tokens by
     never sending allowlisted-IP traffic to the judge
   - sentinel ban verdict gate (line 12949): defense in depth —
     even if the AI says "ban" on an allowlisted IP, this catches it

   Combined with the layered defenses in b09b73c (track_violation,
   _auto_escalate, _nginx_ban, admin_ban_ip), there is now no
   code path that can ban an allowlisted IP. Operator self-ban
   is structurally impossible.

Privilege note: the systemd unit at /root/llm-team-ui/llm-team-ui.service
runs as User=root, so subprocess.run(["fail2ban-client", ...]) and
systemctl reload nginx have permission. The "errors in logs" J was
seeing weren't permission-denied; they were silent non-zero exits.
The new subprocess wrappers surface those.

If the operator later splits the app into a non-root tier
(Opus OB-3 architectural recommendation, deferred), this same
infrastructure still works — the wrappers will then surface
"PermissionError" with full path + uid context, telling the
operator exactly which command needs sudo NOPASSWD or
PolicyKit rule.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

llm_team_ui.py

@@ -7635,7 +7635,10 @@ def admin_security_data():
     sort_by = request.args.get("sort", "hits")
     result = []
     for ip, d in ips.items():
-        if ip.startswith("192.168."):
+        # 2026-04-30: was substring "192.168." — replaced with the
+        # canonical allowlist so 10.x, IPv6 ::1, and operator-added
+        # entries also stay out of the threat panel.
+        if is_allowlisted(ip):
             continue
         result.append({
             "ip": ip, "hits": d["hits"], "exploit_scans": d["exploit_scans"],
@@ -7685,19 +7688,41 @@ def _nginx_ban(ip):
         sec_log.info("NGINX_BAN_BLOCKED ip=%s — allowlisted, refused to write deny rule", ip)
         return
     import subprocess
-    try:
     line = f"deny {ip};\n"
+    # Each step has its own try/except so we know WHICH step failed.
+    # Pre-2026-04-30 a single bare `except: pass` swallowed every
+    # error including PermissionError on the conf file write and
+    # CalledProcessError from systemctl. Sentinel + auto-escalate
+    # logged "BAN" but the request actually never landed in nginx.
+    # Now each failure mode hits sec_log so the operator sees why.
+    try:
         try:
             with open(_NGINX_BAN_FILE) as f:
                 if line in f.read():
                     return
         except FileNotFoundError:
             pass
+    except PermissionError as e:
+        sec_log.warning("NGINX_BAN_READ_DENIED file=%s err=%s — won't dedup, attempting append anyway", _NGINX_BAN_FILE, e)
+    try:
         with open(_NGINX_BAN_FILE, "a") as f:
             f.write(line)
-        subprocess.run(["systemctl", "reload", "nginx"], capture_output=True, timeout=5)
+    except PermissionError as e:
-    except Exception:
+        sec_log.error("NGINX_BAN_WRITE_DENIED ip=%s file=%s err=%s — ban NOT effective at nginx layer", ip, _NGINX_BAN_FILE, e)
-        pass
+        return
+    except Exception as e:
+        sec_log.error("NGINX_BAN_WRITE_ERROR ip=%s err=%s", ip, e)
+        return
+    try:
+        result = subprocess.run(["systemctl", "reload", "nginx"], capture_output=True, text=True, timeout=5)
+        if result.returncode != 0:
+            sec_log.error("NGINX_RELOAD_FAILED ip=%s rc=%d stderr=%s", ip, result.returncode, result.stderr.strip())
+    except subprocess.TimeoutExpired:
+        sec_log.error("NGINX_RELOAD_TIMEOUT ip=%s — systemctl reload nginx didn't finish in 5s", ip)
+    except FileNotFoundError:
+        sec_log.error("NGINX_RELOAD_NO_SYSTEMCTL ip=%s — systemctl not in PATH for service user", ip)
+    except Exception as e:
+        sec_log.error("NGINX_RELOAD_ERROR ip=%s err=%s", ip, e)
 
 def _nginx_unban(ip):
     """Remove IP from nginx deny list and reload."""
@@ -7991,7 +8016,10 @@ def admin_mass_ban():
     results = {"success": 0, "failed": 0, "skipped": 0}
     for ip in ip_list:
         ip = ip.strip()
-        if not ip or ip.startswith("192.168."):
+        # 2026-04-30: substring "192.168." → is_allowlisted so all
+        # trusted networks (LAN gateways, IPv6 loopback, custom
+        # entries) are skipped, not just one /16.
+        if not ip or is_allowlisted(ip):
             results["skipped"] += 1
             continue
         try:
@@ -12713,7 +12741,17 @@ SENTINEL_MODEL = "qwen2.5:latest"
 SENTINEL_INTERVAL = 300  # 5 minutes
 _sentinel_last_pos = 0
 _sentinel_results = []  # last 50 analyses
-_sentinel_stats = {"scans": 0, "bans": 0, "last_run": None, "last_error": None, "next_scan_ts": 0}
+_sentinel_stats = {
+    "scans": 0, "bans": 0, "last_run": None, "last_error": None, "next_scan_ts": 0,
+    # 2026-04-30 J: track consecutive AI-query failures so we can
+    # fire a callback (email alert) when Ollama is sustainedly busy
+    # or unreachable. Pre-fix a model-busy state preserved log
+    # position + skipped the scan with no operator notification.
+    "consecutive_ai_failures": 0,
+    "ai_busy_alerted": False,  # one alert per outage; clears on first success
+}
+SENTINEL_AI_FAILURE_ALERT_THRESHOLD = 3  # consecutive failures before email
+SENTINEL_AI_RETRY_DELAY_SECS = 30        # wait before retry inside same scan
 
 def _sentinel_log_entry(msg):
     """Write to sentinel log file."""
@@ -12761,7 +12799,10 @@ def _sentinel_scan():
             if token.startswith("ip="):
                 ip = token[3:]
                 break
-        if ip and not ip.startswith("192.168."):
+        # 2026-04-30: was substring "192.168." — sentinel now skips
+        # ALL allowlisted IPs from analysis (saves tokens + prevents
+        # the AI judge from getting confused by legitimate admin traffic).
+        if ip and not is_allowlisted(ip):
             ip_activity[ip].append(line)
 
     if not ip_activity:
@@ -12826,21 +12867,85 @@ def _sentinel_scan():
     for ip, summary, _ in analysis_items[:15]:  # max 15 IPs per scan
         prompt += summary + "\n"
 
-    # Query local AI
+    # Query local AI. 2026-04-30 J fix: retry once on model-busy /
-    try:
+    # connection / timeout, and fire an operator callback when the
+    # AI is sustainedly unreachable. Pre-fix a single Ollama hiccup
+    # silently dropped the scan with no notification — operator only
+    # discovered the gap by checking sentinel-status manually.
     cfg = load_config()
     base = cfg["providers"]["ollama"].get("base_url", "http://localhost:11434")
-        resp = requests.post(f"{base}/api/generate", json={
+    body = {
         "model": SENTINEL_MODEL, "prompt": prompt, "stream": False,
-            "options": {"num_ctx": 4096, "temperature": 0.1}
+        "options": {"num_ctx": 4096, "temperature": 0.1},
-        }, timeout=60)
+    }
+    ai_response = None
+    last_err = None
+    for attempt in range(2):  # original try + 1 retry
+        try:
+            resp = requests.post(f"{base}/api/generate", json=body, timeout=60)
             resp.raise_for_status()
             ai_response = resp.json()["response"]
+            break
+        except (requests.exceptions.ConnectionError,
+                requests.exceptions.Timeout,
+                requests.exceptions.ReadTimeout) as e:
+            last_err = f"connection/timeout: {e}"
+            if attempt == 0:
+                _sentinel_log_entry(f"AI_BUSY_RETRY attempt=1 err={str(e)[:80]} sleeping={SENTINEL_AI_RETRY_DELAY_SECS}s")
+                time.sleep(SENTINEL_AI_RETRY_DELAY_SECS)
+                continue
+        except requests.exceptions.HTTPError as e:
+            # 503 Service Unavailable + 429 Too Many = busy; retry.
+            # Other HTTP errors (404 model missing, 400 bad prompt) won't
+            # recover from a retry, so fail fast.
+            sc = getattr(e.response, "status_code", 0)
+            last_err = f"HTTP {sc}: {e}"
+            if sc in (429, 503) and attempt == 0:
+                _sentinel_log_entry(f"AI_BUSY_RETRY attempt=1 status={sc} sleeping={SENTINEL_AI_RETRY_DELAY_SECS}s")
+                time.sleep(SENTINEL_AI_RETRY_DELAY_SECS)
+                continue
+            break
         except Exception as e:
-        _sentinel_stats["last_error"] = f"AI query failed: {e}"
+            last_err = f"unexpected: {e}"
-        _sentinel_log_entry(f"AI_ERROR error={e}")
+            break
+
+    if ai_response is None:
+        _sentinel_stats["consecutive_ai_failures"] += 1
+        _sentinel_stats["last_error"] = f"AI query failed: {last_err}"
+        _sentinel_log_entry(
+            f"AI_ERROR error={last_err} consecutive={_sentinel_stats['consecutive_ai_failures']}"
+        )
+        # Operator callback: fire a security alert email when the AI
+        # has been down for ≥N consecutive scans. One alert per outage —
+        # cleared on next successful scan so a flapping AI doesn't
+        # spam the inbox.
+        if (_sentinel_stats["consecutive_ai_failures"] >= SENTINEL_AI_FAILURE_ALERT_THRESHOLD
+                and not _sentinel_stats["ai_busy_alerted"]):
+            _sentinel_stats["ai_busy_alerted"] = True
+            try:
+                send_security_alert(
+                    f"Sentinel AI unreachable ({_sentinel_stats['consecutive_ai_failures']} consecutive failures)",
+                    f"The sentinel auto-scanner has been unable to reach the LLM judge for "
+                    f"{_sentinel_stats['consecutive_ai_failures']} consecutive scans.\n\n"
+                    f"Last error: {last_err}\n"
+                    f"Model: {SENTINEL_MODEL}\n"
+                    f"Endpoint: {base}\n\n"
+                    f"Threats are being logged and surfaced in the threat-intel UI but "
+                    f"NOT auto-banned during this outage. Manual review recommended.",
+                )
+            except Exception as alert_err:
+                sec_log.error("SENTINEL_ALERT_SEND_FAILED err=%s", alert_err)
         return
 
+    # AI succeeded. Reset the failure counter + clear the alerted flag
+    # so the next outage gets its own notification.
+    if _sentinel_stats["consecutive_ai_failures"] > 0:
+        _sentinel_log_entry(
+            f"AI_RECOVERED after_failures={_sentinel_stats['consecutive_ai_failures']}"
+        )
+    _sentinel_stats["consecutive_ai_failures"] = 0
+    _sentinel_stats["ai_busy_alerted"] = False
+
     # Parse AI response
     try:
         # Extract JSON from response (handle markdown code blocks)
@@ -12866,9 +12971,41 @@ def _sentinel_scan():
     ban_futures = []
 
     def _execute_ban(ip, threat, reason, attack_type):
-        """Execute a single ban — fail2ban + nginx + kill connections."""
+        """Execute a single ban — fail2ban + nginx + kill connections.
-        subprocess.run(["fail2ban-client", "set", "llm-team-exploit", "banip", ip],
+
-                       capture_output=True, text=True, timeout=5)
+        2026-04-30 J fix: actually examine the fail2ban-client result.
+        Pre-fix capture_output=True was set but the result thrown away,
+        so a non-zero exit (jail not configured, IP already banned, IPv6
+        format quirk) silently said "AI_BAN" in the log while the
+        attacker walked through unimpeded. Now logs returncode + stderr
+        on failure so the operator sees WHY the ban didn't stick."""
+        try:
+            result = subprocess.run(
+                ["fail2ban-client", "set", "llm-team-exploit", "banip", ip],
+                capture_output=True, text=True, timeout=5,
+            )
+            if result.returncode != 0:
+                sec_log.error(
+                    "FAIL2BAN_BAN_FAILED ip=%s rc=%d stdout=%s stderr=%s",
+                    ip, result.returncode,
+                    result.stdout.strip()[:200],
+                    result.stderr.strip()[:200],
+                )
+                _sentinel_log_entry(
+                    f"FAIL2BAN_FAILED ip={ip} rc={result.returncode} "
+                    f"err={result.stderr.strip()[:120]}"
+                )
+                # Continue anyway — nginx layer is independent and may
+                # still take effect.
+        except subprocess.TimeoutExpired:
+            sec_log.error("FAIL2BAN_TIMEOUT ip=%s — client didn't return in 5s", ip)
+            _sentinel_log_entry(f"FAIL2BAN_TIMEOUT ip={ip}")
+        except FileNotFoundError:
+            sec_log.error("FAIL2BAN_NOT_INSTALLED ip=%s — fail2ban-client not in PATH", ip)
+            _sentinel_log_entry(f"FAIL2BAN_NOT_INSTALLED ip={ip}")
+        except Exception as e:
+            sec_log.error("FAIL2BAN_ERROR ip=%s err=%s", ip, e)
+            _sentinel_log_entry(f"FAIL2BAN_ERROR ip={ip} err={e}")
         _nginx_ban(ip)
         _kill_connections(ip)
         sec_log.warning("AI_BAN ip=%s threat=%s reason=%s attack=%s", ip, threat, reason, attack_type)
@@ -12892,7 +13029,11 @@ def _sentinel_scan():
             if len(_sentinel_results) > 50:
                 _sentinel_results.pop(0)
 
-            if action == "ban" and ip and not ip.startswith("192.168."):
+            # 2026-04-30: was substring "192.168." — replaced with
+            # canonical is_allowlisted so the sentinel's AI verdict
+            # can't accidentally ban any allowlisted IP that slipped
+            # past the analysis filter (defense in depth).
+            if action == "ban" and ip and not is_allowlisted(ip):
                 ban_futures.append(executor.submit(_execute_ban, ip, threat, reason, attack_type))
             else:
                 _sentinel_log_entry(f"AI_VERDICT ip={ip} threat={threat} action={action} reason={reason} attack_type={attack_type}")