Charon/docs/plans/current_spec.md

Fresh Install Bug Investigation — Comprehensive Plan

Date: 2026-03-17 Source: Community user bug report (see docs/plans/chores.md) Confidence Score: 85% — High certainty based on code analysis; some issues require runtime reproduction to confirm edge cases.

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1. Executive Summary

A community user performed a clean start / fresh installation of Charon and reported 7 bugs. After thorough code analysis, the findings are:

#	Issue	Classification	Severity
1	Missing database values before CrowdSec enabling	LIKELY BUG	Medium
2	CrowdSec requires CLI register before enrollment	BY DESIGN (auto-handled)	Low
3	UI bugs on first enabling CrowdSec	LIKELY BUG	Medium
4	"Required value" error when enabling CrowdSec	CONFIRMED BUG	Medium
5	Monitor TCP port — UI can't add	LIKELY BUG	Medium
6	HTTP always down but HTTPS okay	CONFIRMED BUG	High
7	Security blocked local connection to private IP	BY DESIGN (with UX gap)	Medium

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2. Detailed Investigation

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Issue 1: Missing Database Values Before CrowdSec Enabling

User report: "some database missing values — i think before crowdsec enabling"

Files Examined

• backend/internal/models/security_config.go — SecurityConfig model definition
• backend/internal/models/setting.go — Setting key-value model
• backend/internal/api/routes/routes.go (L93-L120) — AutoMigrate call
• backend/internal/api/handlers/security_handler.go (L69-L215) — GetStatus handler
• backend/cmd/seed/main.go — Seed data (dev only)

Root Cause Analysis

On a fresh install:

1. SecurityConfig table is auto-migrated but has NO seed row. GORM AutoMigrate creates the table schema but does not insert default rows. The SecurityConfig model has no GORM default: tags on key fields like CrowdSecMode, WAFMode, or RateLimitMode — they start as Go zero values (empty strings for strings, false for bools, 0 for ints).

2. GetStatus handler gracefully handles missing SecurityConfig — it queries WHERE name = 'default' and if not found, falls back to static config defaults. However, the settings table is completely empty on a fresh install because no settings are seeded. The handler reads settings like feature.cerberus.enabled, security.crowdsec.enabled, etc. via raw SQL — these return empty results, so the fallback chain works but returns all-disabled state.

3. The Start handler in crowdsec_handler.go creates a SecurityConfig row on first enable (line 466-475), but only when the user toggles CrowdSec on. Before that point, the DB has no security_configs row at all.

4. Fields like WAFParanoiaLevel have gorm:"default:1" but most fields don't. On a fresh install, if any code reads SecurityConfig expecting populated defaults (e.g., crowdsec_api_url), it gets empty strings.

Key issue: The crowdsecPowerMutation in Security.tsx calls updateSetting('security.crowdsec.enabled', 'true', ...) before calling startCrowdsec(). The updateSetting call uses UpdateSettingRequest which has binding:"required" on Value. The value "true" satisfies this. However, no SecurityConfig row exists yet — the Start handler creates it. The sequence is:

1. Frontend calls updateSetting — creates/updates a setting row ✓
2. Frontend calls startCrowdsec() — backend Start handler creates SecurityConfig OR updates existing one ✓

This works, but the GetStatus handler returns stale/empty data between step 1 and step 2 because the optimistic update in the frontend doesn't account for the SecurityConfig not existing yet.

Classification: LIKELY BUG

The system functionally works but returns confusing intermediate states during the first enable sequence. The missing SecurityConfig row and absence of seeded settings means the /security/status endpoint returns an all-empty/disabled state until the user explicitly toggles something.

Proposed Fix

1. Add a database seed step to the main application startup (not just the dev seed tool) that ensures a default SecurityConfig row exists with sensible defaults:

   // In routes.go or main.go after AutoMigrate
   var cfg models.SecurityConfig
   if err := db.Where("name = ?", "default").FirstOrCreate(&cfg, models.SecurityConfig{
       UUID:           "default",
       Name:           "default",
       Enabled:        false,
       CrowdSecMode:   "disabled",
       WAFMode:        "disabled",
       RateLimitMode:  "disabled",
       CrowdSecAPIURL: "http://127.0.0.1:8085",
   }).Error; err != nil {
       log.Warn("Failed to seed default SecurityConfig")
   }
   

2. Add default setting rows for feature flags (feature.cerberus.enabled, etc.) during startup.

---

Issue 2: CrowdSec Still Needs CLI Register Before Enrollment

User report: "crowdsec still needs cli register before you can enroll"

Files Examined

• backend/internal/crowdsec/console_enroll.go (L250-L330) — ensureCAPIRegistered() and checkLAPIAvailable()
• backend/internal/api/handlers/crowdsec_handler.go (L1262-L1360) — ConsoleEnroll handler
• backend/internal/api/handlers/crowdsec_handler.go (L458-L581) — Start handler (bouncer registration)

Root Cause Analysis

The enrollment flow already handles CAPI registration automatically:

1. ConsoleEnroll handler calls h.Console.Enroll(ctx, …)
2. Enroll() calls s.checkLAPIAvailable(ctx) — verifies LAPI is running (retries 5x with exponential backoff, ~45s total)
3. Enroll() calls s.ensureCAPIRegistered(ctx) — checks for online_api_credentials.yaml and runs cscli capi register if missing
4. Then runs cscli console enroll --name <agent> <token>

The auto-registration IS implemented. However, the user may have encountered:

• Timing issue: If CrowdSec was just started, LAPI may not be ready yet. The checkLAPIAvailable retries for ~45s, but if the user triggered enrollment immediately after starting CrowdSec, the timeout may have expired.
• Feature flag: Console enrollment is behind FEATURE_CROWDSEC_CONSOLE_ENROLLMENT feature flag, which defaults to disabled (false). The isConsoleEnrollmentEnabled() method returns false unless explicitly enabled via DB setting or env var. Without this flag, the enrollment endpoint returns 404.
• Error messaging: If CAPI registration fails, the error message might be confusing, leading the user to think they need to manually run cscli capi register.

Classification: BY DESIGN (with potential UX gap)

The auto-registration logic exists and works. The feature flag being off by default means the user likely tried to enroll via the console enrollment UI (which is hidden/unavailable) and ended up using the CLI instead. If they tried via the exposed bouncer registration endpoint, that's a different flow — CAPI registration is only auto-triggered by the console enrollment path, not the bouncer registration path.

Proposed Fix

1. Improve error messaging when LAPI check times out during enrollment
2. Consider auto-running cscli capi register during the Start handler (not just during enrollment)
3. Document the enrollment flow more clearly for users

---

Issue 3: UI Bugs on First Enabling CrowdSec

User report: "ui bugs on first enabling crowdsec"

Files Examined

• frontend/src/pages/Security.tsx (L168-L229) — crowdsecPowerMutation
• frontend/src/pages/Security.tsx (L440-L452) — CrowdSec toggle Switch
• frontend/src/pages/CrowdSecConfig.tsx (L1-L100) — CrowdSec config page
• frontend/src/components/CrowdSecKeyWarning.tsx — Key warning component

Root Cause Analysis

When CrowdSec is first enabled on a fresh install, several things happen in sequence:

1. crowdsecPowerMutation calls updateSetting('security.crowdsec.enabled', 'true', ...)
2. Then calls startCrowdsec() which takes 10-60 seconds
3. Then calls statusCrowdsec() to verify
4. If LAPI ready, ensureBouncerRegistration() runs on the backend
5. onSuccess callback invalidates queries

During this ~30s window:

• The toggle should show loading state, but the Switch component reads crowdsecStatus?.running ?? status.crowdsec.enabled — if crowdsecStatus is stale (from the initial useEffect fetch), the toggle may flicker.
• The CrowdSecConfig page polls LAPI status every 5 seconds — on first enable, this will show "not running" until LAPI finishes starting.
• The CrowdSecKeyWarning component checks key status — on first enable, no bouncer key exists yet, potentially triggering warnings.
• ConfigReloadOverlay shows when isApplyingConfig is true, but the CrowdSec start operation takes significantly longer than typical config operations.

Specific bugs likely seen:

• Toggle flickering between checked/unchecked as different queries return at different times
• Stale "disabled" status shown while CrowdSec is actually starting
• Bouncer key warning appearing briefly before registration completes
• Console enrollment section showing "LAPI not ready" errors

Classification: LIKELY BUG

The async nature of CrowdSec startup (10-60s) combined with multiple independent polling queries creates a poor UX during the first-enable flow.

Proposed Fix

1. Add a dedicated "starting" state to the CrowdSec toggle — show a spinner/loading indicator for the full duration of the start operation
2. Suppress CrowdSecKeyWarning while a start operation is in progress
3. Debounce the LAPI status polling to avoid showing transient "not ready" states
4. Use the mutation's isPending state to disable all CrowdSec-related UI interactions during startup

---

Issue 4: "Required Value" Error When Enabling CrowdSec

User report: "enabling crowdsec throws ui 'required value' error but enables okay"

Files Examined

• frontend/src/pages/Security.tsx (L100-L155) — toggleServiceMutation
• frontend/src/pages/Security.tsx (L168-L182) — crowdsecPowerMutation
• backend/internal/api/handlers/settings_handler.go (L115-L120) — UpdateSettingRequest struct
• frontend/src/api/settings.ts (L27-L29) — updateSetting function

Root Cause Analysis

This is a confirmed bug caused by Gin's binding:"required" validation tag on the Value field:

type UpdateSettingRequest struct {
    Key      string `json:"key" binding:"required"`
    Value    string `json:"value" binding:"required"`
    Category string `json:"category"`
    Type     string `json:"type"`
}

The crowdsecPowerMutation calls:

await updateSetting('security.crowdsec.enabled', enabled ? 'true' : 'false', 'security', 'bool')

When enabled is true, the value "true" satisfies binding:"required". So the direct CrowdSec toggle shouldn't fail here.

The actual bug path: The crowdsecPowerMutation calls updateSetting and then startCrowdsec(). The startCrowdsec() triggers the backend Start handler which internally creates/updates settings. If there's a race condition where the frontend also calls a related updateSetting with an empty value (e.g., a cascading toggle for an uninitialized setting), Gin's binding:"required" treats empty string "" as missing for string fields, producing a validation error.

Broader problem: Any code path that calls updateSetting with an empty value (e.g., clearing an admin whitelist, resetting a configuration) triggers this validation error. This is incorrect — an empty string is a valid value for a setting.

Classification: CONFIRMED BUG

The binding:"required" tag on Value in UpdateSettingRequest means any attempt to set a setting to an empty string "" will fail with a "required" validation error. This is incorrect — empty string is a valid value.

Proposed Fix

Remove binding:"required" from the Value field:

type UpdateSettingRequest struct {
    Key      string `json:"key" binding:"required"`
    Value    string `json:"value"` // Empty string is valid
    Category string `json:"category"`
    Type     string `json:"type"`
}

If value must not be empty for specific keys, add key-specific validation in the handler logic.

Reproduction Steps

1. Fresh install of Charon
2. Navigate to Security dashboard
3. Enable Cerberus (master toggle)
4. Toggle CrowdSec ON
5. Observe toast error containing "required" or "required value"
6. Despite the error, CrowdSec still starts successfully

---

Issue 5: Monitor TCP Port — UI Can't Add

User report: "monitor tcp port ui can't add"

Files Examined

• frontend/src/pages/Uptime.tsx (L342-L500) — CreateMonitorModal
• frontend/src/api/uptime.ts (L80-L97) — createMonitor API
• backend/internal/api/handlers/uptime_handler.go (L30-L60) — CreateMonitorRequest and Create handler
• backend/internal/services/uptime_service.go (L1083-L1140) — CreateMonitor service method

Root Cause Analysis

The frontend CreateMonitorModal supports TCP:

const [type, setType] = useState<'http' | 'tcp'>('http');
// ...
<option value="tcp">{t('uptime.monitorTypeTcp')}</option>

The backend validates:

Type string `json:"type" binding:"required,oneof=http tcp https"`

And TCP format validation:

if monitorType == "tcp" {
    if _, _, err := net.SplitHostPort(urlStr); err != nil {
        return nil, fmt.Errorf("TCP URL must be in host:port format: %w", err)
    }
}

Possible issues:

1. The URL placeholder may not update when TCP is selected — user enters http://... format instead of host:port
2. No client-side format validation that changes based on type
3. The backend error message about host:port format may not surface clearly through the API error chain

Classification: LIKELY BUG

The i18n placeholder string urlPlaceholder is "https://example.com or tcp://host:port". The tcp:// scheme prefix is misleading — the backend's net.SplitHostPort() expects raw host:port (no scheme). A user following the placeholder guidance would submit tcp://192.168.1.1:8080, which fails SplitHostPort parsing because the :// syntax is not a valid host:port format. This is the likely root cause.

Proposed Fix

1. Fix the i18n translation string in frontend/src/locales/en/translation.json: change "urlPlaceholder" from "https://example.com or tcp://host:port" to "https://example.com or host:port" (removing the misleading tcp:// scheme)
2. Update URL placeholder dynamically: placeholder={type === 'tcp' ? '192.168.1.1:8080' : 'https://example.com'}
3. Add helper text below URL field explaining expected format per type
4. Add client-side format validation before submission

---

Issue 6: HTTP Always Down but HTTPS Okay

User report: "http always down but https okay"

Files Examined

• backend/internal/services/uptime_service.go (L727-L810) — checkMonitor method
• backend/internal/security/url_validator.go (L169-L300) — ValidateExternalURL
• backend/internal/network/safeclient.go (L1-L113) — IsPrivateIP, NewSafeHTTPClient

Root Cause Analysis

CONFIRMED BUG caused by SSRF protection blocking private IP addresses for HTTP monitors.

In checkMonitor, HTTP/HTTPS monitors go through:

case "http", "https":
    validatedURL, err := security.ValidateExternalURL(
        monitor.URL,
        security.WithAllowLocalhost(),
        security.WithAllowHTTP(),
        security.WithTimeout(3*time.Second),
    )

Then use:

client := network.NewSafeHTTPClient(
    network.WithTimeout(10*time.Second),
    network.WithDialTimeout(5*time.Second),
    network.WithMaxRedirects(0),
    network.WithAllowLocalhost(),
)

Critical path:

1. ValidateExternalURL resolves the monitor's hostname via DNS
2. It checks ALL resolved IPs against network.IsPrivateIP()
3. IsPrivateIP blocks RFC 1918 ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
4. WithAllowLocalhost() only allows 127.0.0.1, localhost, ::1 — does NOT allow private IPs

If the monitor URL resolves to a private IP (common for self-hosted services), ValidateExternalURL blocks the connection with: "connection to private ip addresses is blocked for security".

Why HTTPS works but HTTP doesn't: The user's HTTPS monitors likely point to public domains (via external DNS/CDN) that resolve to public IPs. HTTP monitors target private upstream IPs directly (e.g., http://192.168.1.100:8080), which fail the SSRF check.

Meanwhile, TCP monitors use raw net.DialTimeout("tcp", ...) with NO SSRF protection at all — they bypass the entire validation chain.

Note: The PR should add a code comment in uptime_service.go at the TCP net.DialTimeout call site acknowledging this deliberate SSRF bypass. TCP monitors currently only accept admin-configured host:port (no URL parsing, no redirects), so the SSRF attack surface is minimal. If SSRF validation is added to TCP in the future, it must also respect WithAllowRFC1918().

Classification: CONFIRMED BUG

Uptime monitoring for self-hosted services on private networks is fundamentally broken by SSRF protection. The WithAllowLocalhost() option is insufficient — it only allows 127.0.0.1/localhost, not the RFC 1918 ranges that self-hosted services use.

Proposed Fix

Add a WithAllowRFC1918() option for admin-configured uptime monitors that selectively unblocks only RFC 1918 private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) while keeping cloud metadata (169.254.169.254), link-local, loopback, and reserved ranges blocked.

Dual-layer fix required — both the URL validation and the safe dialer must be updated:

Layer 1: url_validator.go — Add WithAllowRFC1918() validation option:

// In checkMonitor:
validatedURL, err := security.ValidateExternalURL(
    monitor.URL,
    security.WithAllowLocalhost(),
    security.WithAllowHTTP(),
    security.WithAllowRFC1918(), // NEW: Only unblocks 10/8, 172.16/12, 192.168/16
    security.WithTimeout(3*time.Second),
)

Layer 2: safeclient.go — Add AllowRFC1918 to ClientOptions and respect it in safeDialer:

// In ClientOptions:
AllowRFC1918 bool // Permits connections to RFC 1918 private IPs only

// New option constructor:
func WithAllowRFC1918() Option {
    return func(opts *ClientOptions) {
        opts.AllowRFC1918 = true
    }
}

// In safeDialer, before IsPrivateIP check:
if opts.AllowRFC1918 && isRFC1918(ip.IP) {
    continue // Allow RFC 1918, still block link-local/metadata/reserved
}

// In NewSafeHTTPClient call in checkMonitor:
client := network.NewSafeHTTPClient(
    network.WithTimeout(10*time.Second),
    network.WithDialTimeout(5*time.Second),
    network.WithMaxRedirects(0),
    network.WithAllowLocalhost(),
    network.WithAllowRFC1918(), // NEW: Must match URL validator layer
)

Without the safeDialer fix, connections pass URL validation but are still blocked at dial time. Both layers must allow RFC 1918.

This is safe because uptime monitors are admin-configured only — they require authentication. SSRF protection's purpose is to prevent untrusted user-initiated requests to internal services, not admin-configured health checks. Cloud metadata and link-local remain blocked even with this option.

Reproduction Steps

1. Fresh install of Charon
2. Add a proxy host pointing to a local service (e.g., 192.168.1.100:8080)
3. Monitor auto-creates with http://yourdomain.local
4. Monitor status shows "down" with SSRF error
5. HTTPS monitor to a public domain succeeds

---

Issue 7: Security Blocked Local Connection to Private IP

User report: "security blocked local connection to private ip — status in db just noticed randomly"

Files Examined

• backend/internal/network/safeclient.go (L22-L55) — privateCIDRs list
• backend/internal/network/safeclient.go (L74-L113) — IsPrivateIP function
• backend/internal/security/url_validator.go (L169-L300) — ValidateExternalURL
• backend/internal/services/uptime_service.go (L727-L810) — checkMonitor

Root Cause Analysis

Direct consequence of Issue 6. The SSRF protection blocks ALL RFC 1918 private IP ranges, plus loopback, link-local, and reserved ranges. This protection is applied at:

1. URL Validation (ValidateExternalURL) — blocks at URL validation time
2. Safe Dialer (safeDialer) — blocks at DNS resolution / connection time

The user noticed in the database because:

• The uptime monitor's status field shows "down"
• The heartbeat message stores the SSRF rejection error
• This status persists in the database and is visible through the monitoring UI

Classification: BY DESIGN (with UX gap)

The SSRF protection is correctly implemented for security. However, the application needs to differentiate between:

1. External user-initiated URLs (webhooks, notification endpoints) — MUST block private IPs
2. Admin-configured monitoring targets — SHOULD allow private IPs (trusted, intentional configs)

Proposed Fix

Same as Issue 6 — introduce WithAllowRFC1918() for admin-configured monitoring (both url_validator.go and safeclient.go layers). Additionally:

1. Add a clear UI message when a monitor is down due to SSRF protection
2. Log the specific blocked IP and reason for admin debugging

---

3. Reproduction Steps Summary

Fresh Install Test Sequence

1. Deploy Charon from a clean image (no existing database)
2. Complete initial setup (create admin user)
3. Navigate to Security dashboard

Issue 1: Check Network tab → GET /api/v1/security/status — verify response has populated defaults

Issue 4: Enable Cerberus → Toggle CrowdSec ON → Watch for "required" error toast

Issue 3: During CrowdSec start (~30s), observe UI for flickering/stale states

Issue 5: Uptime → Add Monitor → Select TCP → Enter 192.168.1.1:8080 → Submit

Issues 6 & 7: Add proxy host to private IP → Wait for auto-sync → Check HTTP monitor status

---

4. Implementation Plan

Phase 1: Playwright E2E Tests

Test	File	Description
Fresh security dashboard loads	tests/security/fresh-install.spec.ts	Verify status endpoint returns valid defaults on empty DB
CrowdSec enable flow completes	tests/security/fresh-install.spec.ts	Toggle CrowdSec on, verify no validation errors
Setting update with empty value	tests/security/fresh-install.spec.ts	Verify setting can be cleared
TCP monitor creation	tests/uptime/create-monitor.spec.ts	Create TCP monitor via UI
HTTP monitor for private IP	tests/uptime/private-ip-monitor.spec.ts	Create HTTP monitor for private IP, verify it connects
TCP placeholder updates dynamically	tests/uptime/create-monitor.spec.ts	Verify placeholder changes when switching to TCP type

Phase 1b: Backend Unit Tests

Test	File	Description
UpdateSettingRequest with empty value	settings_handler_test.go	Verify empty string "" is accepted for Value field (Issue 4)
TCP monitor with private IP	uptime_service_test.go	Regression: if SSRF is added to TCP later, private IPs must still work
Cloud metadata blocked with RFC 1918 allowed	safeclient_test.go	169.254.169.254 remains blocked even when AllowRFC1918 = true
safeDialer with RFC 1918 allowance	safeclient_test.go	Dial to 10.x.x.x succeeds with AllowRFC1918, dial to 169.254.x.x fails
ValidateExternalURL with RFC 1918	url_validator_test.go	RFC 1918 IPs pass validation; link-local/metadata still rejected

Phase 2: Backend Fixes

PR-1: Fix binding:"required" on Setting Value (Issue 4)

• Files: settings_handler.go, tests
• Validation: go test ./backend/internal/api/handlers/... -run TestUpdateSetting

PR-2: Seed Default SecurityConfig on Startup (Issue 1)

• Files: routes.go or main.go, tests
• Validation: Fresh start → /security/status returns valid defaults

PR-3: Allow RFC 1918 Private IPs for Uptime Monitors (Issues 6 & 7)

• Files: url_validator.go, safeclient.go, uptime_service.go, tests
• Scope: Add WithAllowRFC1918() option to both ValidateExternalURL and NewSafeHTTPClient/safeDialer. Add isRFC1918() helper. Add code comment at TCP net.DialTimeout call site noting deliberate SSRF bypass.
• Validation: HTTP monitor to 192.168.x.x shows "up"; cloud metadata 169.254.169.254 remains blocked

Phase 3: Frontend Fixes

PR-4: CrowdSec Enable UX (Issues 3 & 4)

• Files: Security.tsx, CrowdSecConfig.tsx, CrowdSecKeyWarning.tsx
• Validation: Playwright: CrowdSec toggle smooth, no error toasts

PR-5: Monitor Creation UX for TCP (Issue 5)

• Files: Uptime.tsx, frontend/src/locales/en/translation.json
• Scope: Fix misleading tcp://host:port in i18n placeholder to host:port, add dynamic placeholder per monitor type
• Validation: Playwright: TCP monitor created via UI

Phase 4: Documentation & Integration Testing

• Update Getting Started docs with fresh install notes
• Run full Playwright suite against fresh install

---

5. Commit Slicing Strategy

Decision: Multiple PRs (5 PRs) for safer and faster review.

Trigger reasons:

• Cross-domain changes (backend security, backend settings, frontend)
• Multiple independent fixes with no inter-dependencies
• Each fix is individually testable and rollbackable

Ordered PR Slices

PR	Scope	Files	Dependencies	Validation Gate
PR-1	Fix binding:"required" on Setting Value	settings_handler.go, tests	None	Unit tests pass
PR-2	Seed default SecurityConfig on startup	routes.go/main.go, tests	None	Fresh start returns valid defaults
PR-3	Allow RFC 1918 IPs for uptime monitors (dual-layer)	url_validator.go, safeclient.go, uptime_service.go, tests	None	HTTP monitor to RFC 1918 IP works; cloud metadata still blocked
PR-4	CrowdSec enable UX improvements	Security.tsx, CrowdSecConfig.tsx, CrowdSecKeyWarning.tsx	PR-1	Playwright: smooth toggle
PR-5	Monitor creation UX for TCP + i18n fix	Uptime.tsx, translation.json	None	Playwright: TCP creation works

Rollback: Each PR is independently revertable. No DB migrations or schema changes.

---

6. E2E Test Gaps

Test Suite	Covers Fresh Install?	Gap
tests/security/security-dashboard.spec.ts	No	Needs fresh-db variant
tests/security/crowdsec-config.spec.ts	No	Needs first-enable test
tests/uptime/*.spec.ts	Unknown	Needs TCP + private IP tests

---

7. Ancillary File Review

• .gitignore — No changes needed
• codecov.yml — No changes needed
• .dockerignore — No changes needed
• Dockerfile — No changes needed

---

8. Acceptance Criteria

1. Issue 1: /api/v1/security/status returns populated defaults on a fresh database
2. Issue 2: Documented as by-design; enrollment auto-registers CAPI when needed
3. Issue 3: No toggle flickering or transient error states during first CrowdSec enable
4. Issue 4: No "required value" error toast when enabling/disabling modules
5. Issue 5: TCP monitor creation succeeds with host:port format; i18n placeholder no longer includes misleading tcp:// scheme; dynamic placeholder guides user
6. Issue 6: HTTP monitors to private IPs succeed for admin-configured uptime monitors
7. Issue 7: Uptime heartbeat messages do not contain "private IP blocked" errors for admin monitors

---

PR-3 Implementation Plan

Title: Allow RFC 1918 IPs for admin-configured uptime monitors (dual-layer SSRF fix) Issues Resolved: Issue 6 (CONFIRMED BUG) + Issue 7 (BY DESIGN / UX gap) Status: APPROVED (all blocking concerns resolved) Dependencies: None (independent of PR-1 and PR-2)

---

Overview

HTTP/HTTPS uptime monitors targeting LAN addresses permanently report "down" on fresh installs. The root cause is a dual-layer SSRF guard: Layer 1 (url_validator.go) rejects private IPs during hostname resolution, and Layer 2 (safeclient.go) re-checks every IP at TCP dial time to defeat DNS rebinding. Because both layers enforce IsPrivateIP, patching only one would produce a monitor that passes URL validation but is silently killed at dial time—the bug would appear fixed in logs but remain broken in practice.

The fix threads a single AllowRFC1918 signal through both layers, visible as the WithAllowRFC1918() functional option. It only unblocks the three RFC 1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16). All other restricted ranges—cloud metadata (169.254.0.0/16 including 169.254.169.254), loopback (127.0.0.0/8, ::1), IPv6 link-local (fe80::/10), IPv6 unique-local (fc00::/7), and all reserved blocks—remain fully blocked regardless of the option.

Authentication posture is verified: Uptime monitor routes (POST /uptime/monitors/:id/check, etc.) live inside the management route group in backend/internal/api/routes/routes.go. That group is nested under protected, which enforces authMiddleware (JWT), and then applies middleware.RequireManagementAccess(). The RFC 1918 bypass is therefore exclusively accessible to authenticated, management-tier users—never to passthrough users or unauthenticated callers.

---

A. File-by-File Change Plan

---

File 1: backend/internal/network/safeclient.go

Package: network

Change 1 — Add RFC 1918 block set

Below the privateBlocks and initOnce declarations, introduce a parallel set of sync.Once-guarded CIDR blocks containing only the three RFC 1918 ranges. These are stored separately so the IsRFC1918 check can remain a cheap, focused predicate without reopening the full IsPrivateIP logic.

New package-level variables (insert after initOnce sync.Once):

var (
    rfc1918Blocks []*net.IPNet
    rfc1918Once   sync.Once
)

var rfc1918CIDRs = []string{
    "10.0.0.0/8",
    "172.16.0.0/12",
    "192.168.0.0/16",
}

New init function (insert after initPrivateBlocks):

func initRFC1918Blocks() {
    rfc1918Once.Do(func() {
        rfc1918Blocks = make([]*net.IPNet, 0, len(rfc1918CIDRs))
        for _, cidr := range rfc1918CIDRs {
            _, block, err := net.ParseCIDR(cidr)
            if err != nil {
                continue
            }
            rfc1918Blocks = append(rfc1918Blocks, block)
        }
    })
}

Change 2 — Add IsRFC1918 exported predicate

Insert after the IsPrivateIP function. This function is exported so url_validator.go (in the security package) can call it via network.IsRFC1918(ip), eliminating duplicated CIDR definitions.

// IsRFC1918 reports whether ip falls within one of the three RFC 1918 private ranges:
// 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16.
//
// Unlike IsPrivateIP, this function does NOT cover loopback, link-local, cloud metadata,
// or any reserved ranges. Use it only to selectively unblock LAN addresses for
// admin-configured features (e.g., uptime monitors) while preserving all other SSRF guards.
func IsRFC1918(ip net.IP) bool {
    if ip == nil {
        return false
    }
    initRFC1918Blocks()
    if ip4 := ip.To4(); ip4 != nil {
        ip = ip4
    }
    for _, block := range rfc1918Blocks {
        if block.Contains(ip) {
            return true
        }
    }
    return false
}

Change 3 — Add AllowRFC1918 to ClientOptions struct

Insert after the DialTimeout field:

// AllowRFC1918 permits connections to RFC 1918 private IP ranges:
// 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16.
//
// SECURITY NOTE: Enable only for admin-configured features (e.g., uptime monitors).
// All other restricted ranges (loopback, link-local, cloud metadata, reserved) remain
// blocked regardless of this flag.
AllowRFC1918 bool

defaultOptions() returns AllowRFC1918: false — no change needed there.

Change 4 — Add WithAllowRFC1918 functional option

Insert after WithDialTimeout:

// WithAllowRFC1918 permits connections to RFC 1918 private addresses.
// Use exclusively for admin-configured outbound calls such as uptime monitors;
// never for user-supplied URLs.
func WithAllowRFC1918() Option {
    return func(opts *ClientOptions) {
        opts.AllowRFC1918 = true
    }
}

Change 5 — Update safeDialer validation loop

Locate the loop inside safeDialer that reads:

for _, ip := range ips {
    if opts.AllowLocalhost && ip.IP.IsLoopback() {
        continue
    }
    if IsPrivateIP(ip.IP) {
        return nil, fmt.Errorf("connection to private IP blocked: %s resolved to %s", host, ip.IP)
    }
}

Replace with:

for _, ip := range ips {
    if opts.AllowLocalhost && ip.IP.IsLoopback() {
        continue
    }
    // Admin-configured monitors may legitimately target LAN services.
    // Allow RFC 1918 ranges only; all other restricted ranges (link-local,
    // cloud metadata 169.254.169.254, loopback, reserved) remain blocked.
    if opts.AllowRFC1918 && IsRFC1918(ip.IP) {
        continue
    }
    if IsPrivateIP(ip.IP) {
        return nil, fmt.Errorf("connection to private IP blocked: %s resolved to %s", host, ip.IP)
    }
}

Change 6 — Update safeDialer IP selection loop

Locate the loop that selects selectedIP:

for _, ip := range ips {
    if opts.AllowLocalhost && ip.IP.IsLoopback() {
        selectedIP = ip.IP
        break
    }
    if !IsPrivateIP(ip.IP) {
        selectedIP = ip.IP
        break
    }
}

Replace with:

for _, ip := range ips {
    if opts.AllowLocalhost && ip.IP.IsLoopback() {
        selectedIP = ip.IP
        break
    }
    if opts.AllowRFC1918 && IsRFC1918(ip.IP) {
        selectedIP = ip.IP
        break
    }
    if !IsPrivateIP(ip.IP) {
        selectedIP = ip.IP
        break
    }
}

Change 7 — validateRedirectTarget (removed from PR-3 scope)

checkMonitor passes network.WithMaxRedirects(0). In NewSafeHTTPClient's CheckRedirect handler, MaxRedirects == 0 causes an immediate return via http.ErrUseLastResponse — meaning validateRedirectTarget is never called for any uptime monitor request. Adding RFC 1918 logic here would ship dead code with no test coverage.

Instead, add the following TODO comment at the top of validateRedirectTarget in safeclient.go:

// TODO: if MaxRedirects > 0 is ever added to uptime monitor checks, also pass
// WithAllowRFC1918() into validateRedirectTarget so that redirect targets to
// RFC 1918 addresses are permitted for admin-configured monitor call sites.

No other functions in safeclient.go require changes.

---

File 2: backend/internal/security/url_validator.go

Package: security

Change 1 — Add AllowRFC1918 field to ValidationConfig

Locate the ValidationConfig struct:

type ValidationConfig struct {
    AllowLocalhost  bool
    AllowHTTP       bool
    MaxRedirects    int
    Timeout         time.Duration
    BlockPrivateIPs bool
}

Add the new field after BlockPrivateIPs:

// AllowRFC1918 permits URLs that resolve to RFC 1918 private addresses.
// Does not disable blocking of loopback, link-local, cloud metadata, or reserved ranges.
AllowRFC1918 bool

Change 2 — Add WithAllowRFC1918 functional option

Insert after the WithMaxRedirects function:

// WithAllowRFC1918 permits hostnames that resolve to RFC 1918 private IP ranges
// (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).
//
// SECURITY NOTE: Use only for admin-controlled call sites such as uptime monitors.
// Cloud metadata (169.254.169.254), link-local, loopback, and all reserved ranges
// are still blocked when this option is active.
func WithAllowRFC1918() ValidationOption {
    return func(c *ValidationConfig) { c.AllowRFC1918 = true }
}

ValidateExternalURL initializer — ensure the default ValidationConfig sets AllowRFC1918: false explicitly. The current initialization block already defaults unlisted bools to false, so no line change is required here.

Change 3 — Update Phase 4 private IP blocking loop in ValidateExternalURL

This is the critical logic change. Locate the IPv4-mapped IPv6 check block and the IsPrivateIP call inside the if config.BlockPrivateIPs block:

if config.BlockPrivateIPs {
    for _, ip := range ips {
        if ip.To4() != nil && ip.To16() != nil && isIPv4MappedIPv6(ip) {
            ipv4 := ip.To4()
            if network.IsPrivateIP(ipv4) {
                return "", fmt.Errorf("connection to private ip addresses is blocked for security (detected IPv4-mapped IPv6: %s)", ip.String())
            }
        }

        if network.IsPrivateIP(ip) {
            sanitizedIP := sanitizeIPForError(ip.String())
            if ip.String() == "169.254.169.254" {
                return "", fmt.Errorf("access to cloud metadata endpoints is blocked for security (detected: %s)", sanitizedIP)
            }
            return "", fmt.Errorf("connection to private ip addresses is blocked for security (detected: %s)", sanitizedIP)
        }
    }
}

Replace with:

if config.BlockPrivateIPs {
    for _, ip := range ips {
        // Handle IPv4-mapped IPv6 form (::ffff:a.b.c.d) to prevent SSRF bypass.
        if ip.To4() != nil && ip.To16() != nil && isIPv4MappedIPv6(ip) {
            ipv4 := ip.To4()
            // RFC 1918 bypass applies even in IPv4-mapped IPv6 form.
            if config.AllowRFC1918 && network.IsRFC1918(ipv4) {
                continue
            }
            if network.IsPrivateIP(ipv4) {
                return "", fmt.Errorf("connection to private ip addresses is blocked for security (detected IPv4-mapped IPv6: %s)", ip.String())
            }
        }

        // Admin-configured monitors may target LAN services; allow RFC 1918 only.
        // Link-local (169.254.x.x), loopback, cloud metadata, and reserved ranges
        // remain blocked unconditionally even when AllowRFC1918 is set.
        if config.AllowRFC1918 && network.IsRFC1918(ip) {
            continue
        }

        if network.IsPrivateIP(ip) {
            sanitizedIP := sanitizeIPForError(ip.String())
            if ip.String() == "169.254.169.254" {
                return "", fmt.Errorf("access to cloud metadata endpoints is blocked for security (detected: %s)", sanitizedIP)
            }
            return "", fmt.Errorf("connection to private ip addresses is blocked for security (detected: %s)", sanitizedIP)
        }
    }
}

No other functions in url_validator.go require changes.

---

File 3: backend/internal/services/uptime_service.go

Package: services

Change 1 — checkMonitor: add WithAllowRFC1918() to URL validation

Locate the security.ValidateExternalURL call inside the case "http", "https": branch:

validatedURL, err := security.ValidateExternalURL(
    monitor.URL,
    // Uptime monitors are an explicit admin-configured feature and commonly
    // target loopback in local/dev setups (and in unit tests).
    security.WithAllowLocalhost(),
    security.WithAllowHTTP(),
    security.WithTimeout(3*time.Second),
)

Replace with:

validatedURL, err := security.ValidateExternalURL(
    monitor.URL,
    // Uptime monitors are admin-configured; LAN targets are a legitimate use-case.
    security.WithAllowLocalhost(),
    security.WithAllowHTTP(),
    // Allow RFC 1918 private ranges for LAN service monitoring. Cloud metadata
    // (169.254.169.254), link-local, and loopback remain blocked.
    security.WithAllowRFC1918(),
    security.WithTimeout(3*time.Second),
)

Change 2 — checkMonitor: add WithAllowRFC1918() to HTTP client

Locate the network.NewSafeHTTPClient call immediately below the URL validation block:

client := network.NewSafeHTTPClient(
    network.WithTimeout(10*time.Second),
    network.WithDialTimeout(5*time.Second),
    // Explicit redirect policy per call site: disable.
    network.WithMaxRedirects(0),
    // Uptime monitors are an explicit admin-configured feature and commonly
    // target loopback in local/dev setups (and in unit tests).
    network.WithAllowLocalhost(),
)

Replace with:

client := network.NewSafeHTTPClient(
    network.WithTimeout(10*time.Second),
    network.WithDialTimeout(5*time.Second),
    // Explicit redirect policy per call site: disable.
    network.WithMaxRedirects(0),
    // Uptime monitors are admin-configured; LAN targets are a legitimate use-case.
    network.WithAllowLocalhost(),
    // Must mirror the WithAllowRFC1918() passed to ValidateExternalURL above.
    // Both the URL validator (DNS resolution) and the safe dialer (TCP connect)
    // enforce SSRF rules independently; both must be relaxed or the fix is partial.
    network.WithAllowRFC1918(),
)

Change 3 — checkMonitor: annotate the TCP bypass

Locate the TCP case:

case "tcp":
    conn, err := net.DialTimeout("tcp", monitor.URL, 10*time.Second)

Add a comment above the dial line:

case "tcp":
    // TCP monitors use net.DialTimeout directly, bypassing the URL validator and
    // safe dialer entirely. This is a deliberate design choice: TCP monitors accept
    // only admin-configured host:port strings (no URL parsing, no redirects, no DNS
    // rebinding surface), so the SSRF attack vector is minimal. If SSRF validation
    // is ever added to TCP monitors, it must also receive WithAllowRFC1918() so that
    // LAN services continue to be reachable.
    conn, err := net.DialTimeout("tcp", monitor.URL, 10*time.Second)

No other functions in uptime_service.go require changes.

---

B. Option Pattern Design

The implementation uses two parallel functional-option systems that must be kept in sync at the call site. They share identical semantics but live in different packages for separation of concerns.

ValidationConfig and ValidationOption (in security package)

The existing struct gains one field:

type ValidationConfig struct {
    AllowLocalhost  bool
    AllowHTTP       bool
    MaxRedirects    int
    Timeout         time.Duration
    BlockPrivateIPs bool
    AllowRFC1918    bool  // NEW: permits 10/8, 172.16/12, 192.168/16
}

New option constructor:

func WithAllowRFC1918() ValidationOption {
    return func(c *ValidationConfig) { c.AllowRFC1918 = true }
}

ClientOptions and Option (in network package)

The existing struct gains one field:

type ClientOptions struct {
    Timeout        time.Duration
    AllowLocalhost bool
    AllowedDomains []string
    MaxRedirects   int
    DialTimeout    time.Duration
    AllowRFC1918   bool  // NEW: permits 10/8, 172.16/12, 192.168/16
}

New option constructor and new exported predicate:

func WithAllowRFC1918() Option {
    return func(opts *ClientOptions) { opts.AllowRFC1918 = true }
}

func IsRFC1918(ip net.IP) bool { /* see File 1, Change 2 above */ }

Coordination in uptime_service.go

The two options are always activated together. The ordering at the call site makes this explicit:

security.ValidateExternalURL(
    monitor.URL,
    security.WithAllowLocalhost(),
    security.WithAllowHTTP(),
    security.WithAllowRFC1918(),   // ← Layer 1 relaxed
    security.WithTimeout(3*time.Second),
)

network.NewSafeHTTPClient(
    network.WithTimeout(10*time.Second),
    network.WithDialTimeout(5*time.Second),
    network.WithMaxRedirects(0),
    network.WithAllowLocalhost(),
    network.WithAllowRFC1918(),    // ← Layer 2 relaxed (must mirror Layer 1)
)

Invariant: Any future call site that enables WithAllowRFC1918() at Layer 1 MUST also enable it at Layer 2 (and vice-versa), or the fix will only partially work. The comments at the call site in uptime_service.go make this constraint explicit.

---

C. Test Plan

All test changes are additive — no existing tests are modified.

backend/internal/network/safeclient_test.go

#	Test Function	Scenario	Expected Result
1	TestIsRFC1918_RFC1918Addresses	Table-driven: 10.0.0.1, 10.255.255.255, 172.16.0.1, 172.31.255.255, 192.168.0.1, 192.168.255.255	IsRFC1918 returns true for all
2	TestIsRFC1918_NonRFC1918Addresses	Table-driven: 169.254.169.254, 127.0.0.1, ::1, 8.8.8.8, 0.0.0.1, 240.0.0.1, fe80::1, fc00::1	IsRFC1918 returns false for all
3	TestIsRFC1918_NilIP	nil IP	Returns false (nil is not RFC 1918; IsPrivateIP handles nil → block)
4	TestIsRFC1918_BoundaryAddresses	172.15.255.255 (just outside range), 172.32.0.0 (just outside), 192.167.255.255 (just outside), 192.169.0.0 (just outside)	IsRFC1918 returns false for all
5	TestSafeDialer_AllowRFC1918_ValidationLoopSkipsRFC1918	ClientOptions{AllowRFC1918: true, DialTimeout: 1s} (no AllowLocalhost), call safeDialer against a host that resolves to 192.168.1.1; the TCP connect will fail (nothing listening), but the returned error must NOT contain "connection to private IP blocked" — absence of that string confirms the RFC 1918 bypass path was taken. White-box test in package network (safeclient_test.go).	Error does not contain "connection to private IP blocked"; confirms if opts.AllowRFC1918 && IsRFC1918(ip.IP) { continue } was executed.
6	TestSafeDialer_AllowRFC1918_BlocksLinkLocal	ClientOptions{AllowRFC1918: true, DialTimeout: 1s}, dial to 169.254.169.254:80	Returns error containing "private IP blocked"
7	TestSafeDialer_AllowRFC1918_BlocksLoopbackWithoutAllowLocalhost	ClientOptions{AllowRFC1918: true, AllowLocalhost: false, DialTimeout: 1s}, dial to 127.0.0.1:80	Returns error; loopback not covered by AllowRFC1918
8	TestNewSafeHTTPClient_AllowRFC1918_BlocksSSRFMetadata	Create client with WithAllowRFC1918(), attempt GET to http://169.254.169.254/	Error; cloud metadata endpoint not accessible
9	TestNewSafeHTTPClient_WithAllowRFC1918_OptionApplied	Create client with WithAllowRFC1918(), verify ClientOptions.AllowRFC1918 is true	Structural test — option propagates to config
10	TestIsRFC1918_IPv4MappedAddresses	Table-driven: IsRFC1918(net.ParseIP("::ffff:192.168.1.1")) → true; IsRFC1918(net.ParseIP("::ffff:169.254.169.254")) → false. White-box test in package network (safeclient_test.go).	true for IPv4-mapped RFC 1918; false for IPv4-mapped link-local/non-RFC-1918. Validates To4() normalization in IsRFC1918.

Implementation note for tests 5–9: Test 5 (TestSafeDialer_AllowRFC1918_ValidationLoopSkipsRFC1918) dials a host resolving to 192.168.1.1 with no AllowLocalhost; the expected outcome is that the error does NOT match "connection to private IP blocked" (a TCP connection-refused error from nothing listening is acceptable — it means the validation loop passed the IP). For tests 6–9, real TCP connections to RFC 1918 addresses are unavailable in the CI environment. Those tests should use httptest.NewServer (which binds to loopback) combined with AllowLocalhost: true and AllowRFC1918: true to verify no validation error occurs. For tests that must confirm a block (e.g., 169.254.169.254), the dialer is called directly with a short DialTimeout — the expected error is the SSRF block error, not a connection-refused error.

backend/internal/security/url_validator_test.go

#	Test Function	Scenario	Expected Result
11	TestValidateExternalURL_WithAllowRFC1918_Permits10x	http://10.0.0.1 with WithAllowHTTP() + WithAllowRFC1918()	Passes URL validation phase (may fail DNS in test env — accept dns resolution failed as OK since that means validation passed)
12	TestValidateExternalURL_WithAllowRFC1918_Permits172_16x	http://172.16.0.1 with WithAllowHTTP() + WithAllowRFC1918()	Same as above
13	TestValidateExternalURL_WithAllowRFC1918_Permits192_168x	http://192.168.1.100 with WithAllowHTTP() + WithAllowRFC1918()	Same as above
14	TestValidateExternalURL_WithAllowRFC1918_BlocksMetadata	http://169.254.169.254 with WithAllowHTTP() + WithAllowRFC1918()	Returns error containing "cloud metadata endpoints is blocked"
15	TestValidateExternalURL_WithAllowRFC1918_BlocksLinkLocal	http://169.254.10.1 with WithAllowHTTP() + WithAllowRFC1918()	Returns error containing "private ip addresses is blocked"
16	TestValidateExternalURL_WithAllowRFC1918_BlocksLoopback	http://127.0.0.1 with WithAllowHTTP() + WithAllowRFC1918() (no WithAllowLocalhost)	Returns error; loopback not covered
17	TestValidateExternalURL_RFC1918BlockedByDefault	http://192.168.1.1 with WithAllowHTTP() only (no RFC 1918 option)	Returns error containing "private ip addresses is blocked" — regression guard
18	TestValidateExternalURL_WithAllowRFC1918_IPv4MappedIPv6Allowed	http://[::ffff:192.168.1.1] with WithAllowHTTP() + WithAllowRFC1918()	Permit (RFC 1918 bypass applies to IPv4-mapped form too)
19	TestValidateExternalURL_WithAllowRFC1918_IPv4MappedMetadataBlocked	http://[::ffff:169.254.169.254] with WithAllowHTTP() + WithAllowRFC1918()	Blocked; cloud metadata remains rejected in mapped form

Implementation note for tests 11–13: ValidateExternalURL calls net.Resolver.LookupIP on literal IP strings. In Go, LookupIP on a literal IP (e.g., "192.168.1.1") returns that IP immediately without a real DNS query. So tests 11–13 should succeed at validation and return either a normalized URL (success) or a DNS timeout error if the test environment's resolver behaves unexpectedly. Both outcomes are acceptable; the important invariant is that the returned error must NOT contain "private ip addresses is blocked".

backend/internal/services/uptime_service_test.go

#	Test Function	Scenario	Expected Result
20	TestCheckMonitor_HTTP_LocalhostSucceedsWithPrivateIPBypass	Start an httptest.NewServer on loopback, create HTTP monitor pointing to its URL, call checkMonitor — verifies that WithAllowLocalhost + WithAllowRFC1918 together produce a "up" result	Monitor status "up", heartbeat message "HTTP 200"
21	TestCheckMonitor_TCP_AcceptsRFC1918Address	TCP monitor with host:port format pointing to a server listening on 127.0.0.1, call checkMonitor	Success (TCP uses net.DialTimeout, no SSRF layer to relax)

---

D. Security Review Checklist

Every item below is a security property that the implementation must satisfy. Each entry names the property, which code enforces it, and how to verify it.

#	Property	Enforced By	Verification Method
1	Cloud metadata remains blocked. 169.254.169.254 (AWS/GCP/Azure metadata service) is never reachable, even with AllowRFC1918 active.	IsRFC1918 returns false for 169.254.x.x (link-local, not RFC 1918). Both ValidateExternalURL and safeDialer will still call IsPrivateIP which blocks 169.254.0.0/16.	Test 8 + Test 14.
2	Full link-local range blocked. Not just 169.254.169.254 but the entire 169.254.0.0/16 range is blocked.	Same as #1. IsPrivateIP covers 169.254.0.0/16. IsRFC1918 excludes this range.	Test 6 + Test 15.
3	Loopback does not gain blanket bypass. 127.0.0.0/8 and ::1 are not unblocked by AllowRFC1918. Only AllowLocalhost can bypass loopback, and it is not added unexpectedly.	IsRFC1918 only covers the three RFC 1918 ranges. Loopback is handled independently by AllowLocalhost.	Test 7 + Test 16.
4	IPv6 unique-local and link-local remain blocked. fc00::/7 and fe80::/10 are not unblocked. RFC 1918 is IPv4-only.	IsRFC1918 converts to IPv4 via To4(); it returns false for all IPv6 addresses.	Test 2 (fe80::1, fc00::1 in TestIsRFC1918_NonRFC1918Addresses).
5	Reserved ranges remain blocked. 0.0.0.0/8, 240.0.0.0/4, 255.255.255.255/32 are not unblocked.	Same as above — not in rfc1918CIDRs.	Test 2 (0.0.0.1, 240.0.0.1 in TestIsRFC1918_NonRFC1918Addresses).
6	RFC 1918 bypass is bounded precisely. Addresses just outside the three RFC 1918 ranges (e.g., 172.15.255.255, 172.32.0.0) are not treated as RFC 1918.	net.ParseCIDR + block.Contains provide exact CIDR boundary enforcement.	Test 4 (TestIsRFC1918_BoundaryAddresses).
7	IPv4-mapped IPv6 addresses are handled. ::ffff:192.168.1.1 is permitted with AllowRFC1918; ::ffff:169.254.169.254 is not.	IsRFC1918 normalizes to IPv4 via To4() before CIDR check. The URL validator's IPv4-mapped branch also checks IsRFC1918 before IsPrivateIP. Unit-level coverage provided by Test 10 (TestIsRFC1918_IPv4MappedAddresses).	Test 10 + Test 18 + Test 19.
8	Option is not accessible to unauthenticated users. The uptime monitor check routes are behind authMiddleware + middleware.RequireManagementAccess().	routes.go nests uptime routes inside management group which is protected.Group("/") with RequireManagementAccess().	Code review of backend/internal/api/routes/routes.go (confirmed: management.POST("/uptime/monitors/:id/check", ...) at line 461).
9	Option is not applied to user-facing URL validation. Webhook URLs, notification URLs, and other user-supplied inputs use ValidateExternalURL without WithAllowRFC1918().	WithAllowRFC1918() is only added in checkMonitor in uptime_service.go. No other ValidateExternalURL call site is modified.	Grep all ValidateExternalURL call sites; verify only uptime_service.go carries WithAllowRFC1918().
10	Both layers are consistently relaxed. If WithAllowRFC1918() is at Layer 1 (URL validator), it is also at Layer 2 (safe dialer). Partial bypass is not possible.	Comment in uptime_service.go creates a code-review anchor.	Cross-reference Layer 1 and Layer 2 call sites in checkMonitor.
11	DNS rebinding is still defeated. The safe dialer re-resolves the hostname at connect time and re-applies the same RFC 1918 policy. A hostname that resolves to a public IP during validation cannot be swapped for a private non-RFC-1918 IP at connect time.	safeDialer validates ALL resolved IPs against the same logic as the URL validator. IsPrivateIP is still called for non-RFC-1918 addresses.	Existing TestSafeDialer_BlocksPrivateIPs remains unchanged and continues to pass.
12	IsRFC1918(nil) returns false, not true. IsPrivateIP(nil) returns true (block-by-default safety). IsRFC1918(nil) should return false because nil is not an RFC 1918 address — it would fall through to IsPrivateIP which handles the nil case.	Early nil check in IsRFC1918: if ip == nil { return false }.	Test 3 (TestIsRFC1918_NilIP).
13	CheckMonitor exported wrapper propagates the fix automatically. The exported CheckMonitor method delegates directly to the unexported checkMonitor. All RFC 1918 option changes applied inside checkMonitor take effect for both entry points without separate configuration.	uptime_service.go: CheckMonitor calls checkMonitor without re-creating the HTTP client or invoking ValidateExternalURL independently.	Code review: verify CheckMonitor does not construct its own HTTP client or URL validation path outside of checkMonitor.
14	Coordination invariant is comment-enforced; integration test can assert the contract. The requirement that Layer 1 (WithAllowRFC1918() in ValidateExternalURL) and Layer 2 (WithAllowRFC1918() in NewSafeHTTPClient) are always relaxed together is documented via the inline comment at the NewSafeHTTPClient call site in checkMonitor. Partial bypass — relaxing only one layer — is not possible silently because the code-review anchor makes the intent explicit. A TestCheckMonitor integration test (Test 20) can additionally assert the "up" outcome to confirm both layers cooperate.	Comment in uptime_service.go: "Must mirror the WithAllowRFC1918() passed to ValidateExternalURL above."	Cross-reference both WithAllowRFC1918() call sites in checkMonitor; any future call site adding only one of the two options is a mis-use detectable at code review.

---

E. Commit Message

fix(uptime): allow RFC 1918 IPs for admin-configured monitors

HTTP/HTTPS uptime monitors targeting LAN addresses (e.g., 192.168.x.x,
10.x.x.x, 172.16.x.x) permanently reported "down" on fresh installs.
The SSRF protection layer silently blocked private IPs at two independent
checkpoints — URL validation and TCP dial time — causing monitors that
pointed to self-hosted LAN services to always fail.

Introduce WithAllowRFC1918() as a functional option in both the
url_validator (security package) and NewSafeHTTPClient / safeDialer
(network package). A new IsRFC1918() exported predicate in the network
package covers exactly the three RFC 1918 ranges without touching the
broader IsPrivateIP logic.

Apply WithAllowRFC1918() exclusively in checkMonitor() (uptime_service.go)
for the http/https case. Both layers are relaxed in concert; relaxing only
one produces a partial fix where URL validation passes but the TCP dialer
still blocks the connection.

Security properties preserved:
- 169.254.169.254 and the full 169.254.0.0/16 link-local range remain
  blocked unconditionally (not RFC 1918)
- Loopback (127.0.0.0/8, ::1) is not affected by this option
- IPv6 unique-local (fc00::/7) and link-local (fe80::/10) remain blocked
- Reserved ranges (0.0.0.0/8, 240.0.0.0/4, broadcast) remain blocked
- The bypass is only reachable by authenticated management-tier users
- No user-facing URL validation call site is modified

Add an explanatory comment at the TCP net.DialTimeout call site in
checkMonitor documenting the deliberate SSRF bypass for TCP monitors.

Fixes issues 6 and 7 from the fresh-install bug report.