README.md

@@ -223,8 +223,14 @@ notification endpoint set, changes show only on the dashboard; see
     - Certificate CN, issuer, or SANs changed (replacement detected, reports old
       and new CN and issuer).
     - TLS connection failure to a previously-reachable IP:443 (handshake error,
-      timeout, connection refused after previously succeeding).
+      timeout, or connection refused when port 443 closed after the port check
+      that found it open).
     - TLS recovery: a previously-failing IP:443 now completes a handshake again.
+- A port check that finds port 443 closed removes the certificate entries for
+  that IP address, without a notification of its own: the port change
+  notification reports the closed port. When the port opens again, the next TLS
+  check saves the certificate as new, without a certificate change or recovery
+  notification.
 
 ### Notifications
 
@@ -294,8 +300,10 @@ clears them.
   port entry left with no name goes, so the dashboard and `/api/v1/status` no
   longer list or count it. The first check's port checks remove the port entries
   of addresses no configured name has.
-- Each port check also removes the certificate entries for an address their name
+- Each port check also removes, without a notification, the certificate entries
-  no longer resolves to, except while none of the name's nameservers answer.
+  for an address whose port 443 it found closed, and those for an address their
+  name no longer resolves to, except while none of the name's nameservers
+  answer.
 
 ### Web Dashboard
 

TODO.md

@@ -19,6 +19,8 @@ trial run of the finished image: https://git.eeqj.de/sneak/dnswatcher/issues/149
 
 # Completed Steps
 
+- 2026-10-13: a port check that finds port 443 closed removes that address's
+  certificate entries, so none is left shown as `ok` (closes #265).
 - 2026-10-13: a state file holding `{}`, or leaving out a section, loads with
   that section empty; the first check no longer crashes on it (closes #267).
 - 2026-10-13: a stop before the first scan completes sends no startup

internal/watcher/removed_test.go

@@ -3,6 +3,7 @@ package watcher_test
 import (
 	"maps"
 	"slices"
+	"strings"
 	"testing"
 
 	"sneak.berlin/go/dnswatcher/internal/state"
@@ -222,3 +223,67 @@ func TestCertificateStateForAnAddressGone(t *testing.T) {
 		})
 	}
 }
+
+// TestCertificateStateForAPortClosed runs the port checks on hostname
+// and port state built here for a configured hostname at ip1, whose
+// port 443 the previous check found open and whose certificate entry
+// is ok. The port is closed now: the certificate entry is removed, and
+// only the Port Change is notified. When the port opens again, the next
+// TLS check saves the certificate as new and notifies nothing about it.
+// Nothing is looked up.
+func TestCertificateStateForAPortClosed(t *testing.T) {
+	t.Parallel()
+
+	cfg := defaultTestConfig(t)
+	cfg.Hostnames = []string{host}
+
+	deps := newTestDeps(t, cfg)
+	w := watcher.NewForTest(
+		cfg, deps.state, nil,
+		deps.portChecker, deps.tlsChecker, deps.notifier,
+	)
+	w.SetFirstRun(false)
+
+	certKey := ip1 + ":443:" + host
+
+	deps.state.SetHostnameState(host, saved(
+		map[string]*state.NameserverRecordState{
+			nsA: answered(map[string][]string{"A": {ip1}}),
+		},
+	))
+	deps.state.SetPortState(ip1+":443", &state.PortState{
+		Open: true, Hostnames: []string{host},
+	})
+	deps.state.SetCertificateState(certKey, &state.CertificateState{
+		CommonName: host, Status: "ok",
+	})
+	deps.portChecker.closed = true
+
+	w.CheckAllPorts(t.Context())
+
+	if _, ok := deps.state.GetCertificateState(certKey); ok {
+		t.Errorf("certificate entry %s kept with port 443 closed", certKey)
+	}
+
+	sent := deps.notifier.getNotifications()
+	if title := "Port Change: " + ip1 + ":443"; len(sent) != 1 ||
+		sent[0].Title != title {
+		t.Errorf("sent %v, want one %q", sent, title)
+	}
+
+	deps.portChecker.closed = false
+
+	w.CheckAllPorts(t.Context())
+	w.RunTLSChecks(t.Context())
+
+	cert, ok := deps.state.GetCertificateState(certKey)
+	if !ok || cert.Status != "ok" {
+		t.Errorf("certificate entry %s after port 443 opened: %+v", certKey, cert)
+	}
+
+	for _, n := range deps.notifier.getNotifications() {
+		if strings.HasPrefix(n.Title, "TLS") {
+			t.Errorf("sent %v, want no TLS notification", n)
+		}
+	}
+}

internal/watcher/watcher.go

@@ -978,7 +978,8 @@ func (w *Watcher) checkAllPorts(ctx context.Context) {
 
 	// Phase 3: Remove port state entries that no longer have
 	// any hostname referencing them, and certificate entries for
-	// an address their name no longer has.
+	// an address whose port 443 is closed or that their name no
+	// longer has.
 	w.cleanupStalePorts(associations)
 	w.cleanupStaleCertificates()
 }
@@ -1065,13 +1066,21 @@ func (w *Watcher) cleanupStalePorts(
 }
 
 // cleanupStaleCertificates removes the certificate entries for an
-// address their name no longer resolves to. An entry saved for a name
+// address whose port 443 was found closed, and for an address their
-// none of whose nameservers answered is kept: that name's addresses are
+// name no longer resolves to. An entry saved for a name none of whose
-// not known, not gone.
+// nameservers answered is kept unless its port is closed: that name's
+// addresses are not known, not gone.
 func (w *Watcher) cleanupStaleCertificates() {
 	for _, key := range w.state.GetAllCertificateKeys() {
 		ip, hostname := parseCertKey(key)
 
+		ps, ok := w.state.GetPortState(fmt.Sprintf("%s:%d", ip, tlsPort))
+		if ok && !ps.Open {
+			w.state.DeleteCertificateState(key)
+
+			continue
+		}
+
 		if slices.Contains(w.collectIPs(hostname), ip) ||
 			w.noNameserverAnswered(hostname) {
 			continue