Health card: public addresses up top, checks as tiles

The public IPv4 and IPv6 addresses, with their uplink, lead the card.
Every other check is a tile with a plain-word status, the raw setting
and, when it fails, what is wrong. The header counts passing or failing
checks.

README.md

@@ -40,19 +40,6 @@ dependencies on the server: the binary installs, updates and removes itself.
 - **HTTPS built in:** Let's Encrypt, a self-signed certificate, your own
   certificate files, or plain HTTP behind a reverse proxy.
 
-## Screenshots
-
-| | |
-|---|---|
-| ![Peers list with status, endpoint, latency sparklines and 30-day traffic](screenshots/peers.png) | ![Peer page with traffic and latency charts, connection details and history](screenshots/peer.png) |
-| **Peers:** status, endpoint, latency and traffic at a glance | **Peer:** traffic, latency, connection history and settings |
-| ![Server page with health checks, interface, endpoint, client defaults and firewall](screenshots/server.png) | ![Settings with users, web interface and API tokens](screenshots/settings.png) |
-| **Server:** health, address plan, client defaults and firewall | **Settings:** users, web interface and API tokens |
-| ![My account page with profile, password and own app tokens](screenshots/account.png) | ![Sign-in page](screenshots/login.png) |
-| **My account:** profile, password and your app tokens | **Sign-in** |
-
-The screenshots show sample data from the built-in simulator.
-
 ## Security
 
 - **Client private keys are never stored.** A config is shown once, as a
@@ -65,7 +52,8 @@ The screenshots show sample data from the built-in simulator.
   `CAP_NET_ADMIN` and `CAP_NET_BIND_SERVICE`, and can write only to
   `/opt/ghostwire`.
 - **Sign-in:** one or more users, all admins. Passwords are stored as argon2id hashes.
-  After 5 failed attempts, sign-in is locked for 15 minutes. Sessions use an
+  After 5 failed attempts from one IP address, sign-in from it is locked for 15
+  minutes; wrong two-step codes count too. Sessions use an
   HttpOnly, SameSite=Strict cookie and last 12 hours by default.
 - **Two-step sign-in:** each user can add an authenticator app (TOTP) and
   passkeys under My account. A passkey signs in on its own, without username
@@ -229,7 +217,7 @@ After editing `config.json` by hand, run `sudo systemctl reload ghostwire`.
 | File | Content |
 |---|---|
 | `GHOSTWIRE` | the program |
-| `config.json` | all settings, server key, peers, token hashes (0600) |
+| `config.json` | all settings, server key, peers, pending setup links with their PINs, user password hashes, authenticator app secrets, passkeys, recovery code and token hashes (0600) |
 | `stats.json` | traffic and connection history per peer |
 | `geo-country.mmdb`, `geo-asn.mmdb` | DB-IP Lite databases for country and network lookups |
 | `GHOSTWIRE.jsonl` | log, one JSON object per line. Changes carry `"audit":true` |
@@ -241,24 +229,26 @@ Base path `/api/v1`. The web interface signs in with a session cookie; every
 user is an admin. Apps and scripts use `Authorization: Bearer <token>`; create
 the token under Settings → Pair iOS app. A token belongs to the user who made
 it and is revoked when that user is deleted. A read-only token may only use
-GET. Full-access tokens can do everything the web interface does except backup
+GET. Full-access tokens can do everything the web interface does except the
-and restore. Users, passwords and API tokens need a full-access token even for
+endpoints marked "signed in": users, passwords, API tokens, the sign-in rules,
-reading.
+backup and restore.
 
 For a user with two-step sign-in, `POST /auth/login` answers
 `{"mfa": true, "ticket": "…", "methods": ["key", "totp", "recovery"]}`
 instead of starting a session; the ticket is good for 5 minutes, and one of
 the `/auth/login/…` steps turns it into the session. `PATCH /settings`
-`{"signin": {"requireMfa": true}}` requires two-step sign-in for every user.
+`{"signin": {"requireMfa": true}}` requires two-step sign-in for every user;
+only a signed-in user can change it.
 
 `POST /users` and `POST /users/{id}/reset-password` take
 `{"password": "…", "mustChangePassword": true}`; with `true` (the default) the
 user can do nothing but choose a new password at the next sign-in.
 
 ```
-POST   /auth/login · /auth/logout        GET /auth/me        POST /auth/password (own password)
+POST   /auth/login · /auth/logout        GET /auth/me
-GET    /users      POST /users           PATCH /users/{id}   DELETE /users/{id}
+signed in: POST /auth/password (own password)
-POST   /users/{id}/reset-password    POST /users/{id}/reset-mfa
+signed in: GET|POST /users · PATCH|DELETE /users/{id}
+signed in: POST /users/{id}/reset-password · /users/{id}/reset-mfa
 GET    /auth/options (public: is passkey sign-in offered here)
 POST   /auth/login/totp · /auth/login/recovery {"ticket", "code"}
 POST   /auth/login/key/begin {"ticket"} · /auth/login/key/finish?ticket=  (body: the WebAuthn credential)
@@ -276,8 +266,7 @@ GET    /peers/{id}/latency               (24 h, one point per 5 minutes)
 GET    /peers/{id}/setup (not read-only) DELETE /peers/{id}/setup
 GET    /settings       PATCH /settings   POST /restart
 GET    /logs?level=&limit=&audit=1       GET /logs/download
-GET    /tokens     POST /tokens          DELETE /tokens/{id}
+signed in: GET|POST /tokens · DELETE /tokens/{id} · GET /backup · POST /restore
-signed in: GET /backup · POST /restore
 public: GET /setup/{token} · POST /setup/{token} {"pin"}   (what a setup link opens)
 ```
 
@@ -307,8 +296,9 @@ override a drop in another table, so if ufw or firewalld is active, allow UDP
 ## iOS app
 
 The native iPhone app (SwiftUI, iOS 17+) lives in its own project,
-GHOSTWIRE-Companion. It does everything the web interface does except
+GHOSTWIRE-Companion. It manages peers, the server and the app settings and
-password, API tokens and backups. Pair it in the web interface under
+shows stats and logs. Users, passwords, API tokens, two-step sign-in, backup
+and restore stay in the web interface. Pair it in the web interface under
 Settings → Pair iOS app: scan the QR code, or tap "Copy pairing code" and paste
 it into the app's "Enter manually". Self-signed certificates are pinned during
 pairing.

api.go

@@ -97,17 +97,6 @@ func (a *App) guard(adminOnly bool, h http.HandlerFunc) http.HandlerFunc {
 	}
 }
 
-// fullAccess refuses read-only tokens, also for GET.
-func fullAccess(h http.HandlerFunc) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		if who(r).Scope == "ro" {
-			writeJSON(w, http.StatusForbidden, map[string]string{"error": "this token is read-only"})
-			return
-		}
-		h(w, r)
-	}
-}
-
 // applyResult saves-then-applies: the config is already stored, so a kernel
 // error is reported but does not undo the change.
 func (a *App) apply() string {
@@ -121,8 +110,6 @@ func (a *App) routes() http.Handler {
 	mux := http.NewServeMux()
 	g := func(pattern string, h http.HandlerFunc) { mux.HandleFunc(pattern, a.guard(false, h)) }
 	adm := func(pattern string, h http.HandlerFunc) { mux.HandleFunc(pattern, a.guard(true, h)) }
-	// full is for signed-in users and full-access tokens, even for reading.
-	full := func(pattern string, h http.HandlerFunc) { mux.HandleFunc(pattern, a.guard(false, fullAccess(h))) }
 
 	mux.HandleFunc("POST /api/v1/auth/login", a.login)
 	mux.HandleFunc("POST /api/v1/auth/logout", a.logout)
@@ -146,13 +133,13 @@ func (a *App) routes() http.Handler {
 	adm("DELETE /api/v1/auth/mfa/keys/{id}", a.keyRemove)
 	adm("POST /api/v1/auth/mfa/recovery-codes", a.newRecoveryCodesHandler)
 	g("GET /api/v1/auth/me", a.me)
-	full("POST /api/v1/auth/password", a.changePassword)
+	adm("POST /api/v1/auth/password", a.changePassword)
-	full("GET /api/v1/users", a.listUsers)
+	adm("GET /api/v1/users", a.listUsers)
-	full("POST /api/v1/users", a.createUser)
+	adm("POST /api/v1/users", a.createUser)
-	full("PATCH /api/v1/users/{id}", a.patchUser)
+	adm("PATCH /api/v1/users/{id}", a.patchUser)
-	full("POST /api/v1/users/{id}/reset-password", a.resetPassword)
+	adm("POST /api/v1/users/{id}/reset-password", a.resetPassword)
-	full("DELETE /api/v1/users/{id}", a.deleteUser)
+	adm("DELETE /api/v1/users/{id}", a.deleteUser)
-	full("POST /api/v1/users/{id}/reset-mfa", a.resetMFA)
+	adm("POST /api/v1/users/{id}/reset-mfa", a.resetMFA)
 
 	g("GET /api/v1/status", a.status)
 	g("GET /api/v1/stats", a.allStats)
@@ -182,13 +169,14 @@ func (a *App) routes() http.Handler {
 	mux.HandleFunc("POST /api/v1/setup/{token}", a.setupRedeem)
 
 	// Full-access tokens (the iOS app) may change app settings, read logs and
-	// manage users and tokens. Backups need a signed-in user.
+	// restart. Users, passwords, API tokens, the sign-in rules and backups
+	// need a signed-in user.
 	g("GET /api/v1/settings", a.getSettings)
 	g("PATCH /api/v1/settings", a.patchSettings)
 	g("POST /api/v1/restart", a.restart)
-	full("GET /api/v1/tokens", a.listTokens)
+	adm("GET /api/v1/tokens", a.listTokens)
-	full("POST /api/v1/tokens", a.createToken)
+	adm("POST /api/v1/tokens", a.createToken)
-	full("DELETE /api/v1/tokens/{id}", a.deleteToken)
+	adm("DELETE /api/v1/tokens/{id}", a.deleteToken)
 	g("GET /api/v1/logs", a.logs)
 	g("GET /api/v1/logs/download", a.downloadLog)
 	adm("GET /api/v1/backup", a.backup)
@@ -232,7 +220,7 @@ func (a *App) login(w http.ResponseWriter, r *http.Request) {
 	if err != nil {
 		slog.Warn("login failed", "user", in.Username, "remote", ip, "reason", err.Error())
 		code := http.StatusUnauthorized
-		if errors.Is(err, errLocked) {
+		if errors.Is(err, errLocked) || errors.Is(err, errBusy) {
 			code = http.StatusTooManyRequests
 		}
 		writeJSON(w, code, map[string]string{"error": err.Error()})
@@ -270,9 +258,6 @@ func (a *App) me(w http.ResponseWriter, r *http.Request) {
 		"id": p.UserID, "name": p.Name, "isAdmin": p.IsAdmin, "scope": p.Scope,
 		"mustChangePassword": p.MustChangePassword, "mfaSetupRequired": p.MFASetupRequired, "version": version, "session": p.Session,
 	}
-	if p.TokenID != "" {
-		out["tokenId"] = p.TokenID // lets an app find its own token in /tokens
-	}
 	if _, u := a.store.Get().userByID(p.UserID); u != nil {
 		out["username"], out["note"], out["created"] = u.Username, u.Note, u.Created
 	}
@@ -1008,15 +993,14 @@ func (a *App) issueConfig(w http.ResponseWriter, r *http.Request) {
 func (a *App) getSettings(w http.ResponseWriter, r *http.Request) {
 	cfg := a.store.Get()
 	writeJSON(w, http.StatusOK, map[string]any{
-		"web":           cfg.Web,
+		"web":         cfg.Web,
-		"log":           cfg.Log,
+		"log":         cfg.Log,
-		"stats":         cfg.Stats,
+		"stats":       cfg.Stats,
-		"decoy":         cfg.Decoy,
+		"decoy":       cfg.Decoy,
-		"signin":        cfg.SignIn,
+		"signin":      cfg.SignIn,
-		"geo":           a.geoStatus(),
+		"geo":         a.geoStatus(),
-		"adminUsername": a.username(cfg, who(r).UserID), // kept for older iOS app versions
+		"fingerprint": a.tls.Fingerprint(),
-		"fingerprint":   a.tls.Fingerprint(),
+		"logPath":     a.logPath,
-		"logPath":       a.logPath,
 	})
 }
 
@@ -1026,8 +1010,8 @@ func (a *App) patchSettings(w http.ResponseWriter, r *http.Request) {
 		writeErr(w, err)
 		return
 	}
-	if _, ok := m["adminUsername"]; ok {
+	if _, ok := m["signin"]; ok && !who(r).IsAdmin {
-		writeErr(w, badRequest("usernames are changed under /users"))
+		writeJSON(w, http.StatusForbidden, map[string]string{"error": "API tokens cannot change the sign-in rules; sign in to the web interface"})
 		return
 	}
 	var restart bool

app.css

@@ -144,6 +144,8 @@ td { padding: 12px; border-bottom: 1px solid var(--line-2); vertical-align: midd
 tr:last-child td { border-bottom: 0; }
 .num { text-align: right; font-variant-numeric: tabular-nums; white-space: nowrap; }
 td .note { font-size: 12px; color: var(--ink-3); }
+a.pname { color: var(--ink); font-weight: 600; text-decoration: none; }
+a.pname:hover, a.pname:focus-visible { color: var(--ink); text-decoration: underline; text-underline-offset: 3px; }
 .empty { padding: 24px 12px; margin: 0; text-align: center; color: var(--ink-3); }
 
 /* forms */
@@ -171,10 +173,28 @@ fieldset { border: 0; margin: 0; padding: 0; min-width: 0; display: flex; flex-d
 .kv dt { color: var(--ink-2); }
 .kv dd { margin: 0; min-width: 0; overflow-wrap: anywhere; }
 
-/* checks */
+/* health: public addresses, then one tile per check */
-.chk { display: flex; gap: 10px; align-items: center; padding: 10px 0; border-bottom: 1px solid var(--line-2); font-size: 13px; }
+.hchead { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; }
-.chk:last-child { border-bottom: 0; }
+.hchead > span { font-size: 13px; color: var(--ink-2); }
-.chk b { font-weight: 500; min-width: 160px; }
+.hchead > span.bad { color: var(--bad-ink); font-weight: 500; }
+.hcaddrs { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 12px; margin-top: 16px; }
+.hcaddr { background: var(--ground); border-radius: 10px; padding: 14px 16px; min-width: 0; }
+.hcaddr .l { display: flex; align-items: center; gap: 8px; font-size: 12px; color: var(--ink-2); }
+.hcaddr .v { margin-top: 4px; font-size: 15px; font-weight: 500; overflow-wrap: anywhere; }
+.hcaddr .v.mono { font-size: 20px; }
+.hcaddr .n { font-family: var(--sans); font-size: 12px; font-weight: 400; color: var(--ink-2); }
+.hcaddr.bad { background: #fdf6f5; box-shadow: inset 0 0 0 1px #e6b3b0; }
+.hcaddr.bad .v { color: var(--bad-ink); }
+.hctiles { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 12px; margin-top: 12px; }
+.hctile { border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; display: flex; flex-direction: column; gap: 4px; min-width: 0; }
+.hctile .l { display: flex; align-items: center; gap: 8px; font-size: 12px; color: var(--ink-2); }
+.hctile .l > span:first-child { flex: 1; min-width: 0; }
+.hctile .s { font-size: 15px; font-weight: 500; }
+.hctile .r { font-size: 11.5px; color: var(--ink-3); overflow-wrap: anywhere; }
+.hctile .p { font-size: 12.5px; color: var(--bad-ink); overflow-wrap: anywhere; }
+.hctile.bad { border-color: #e6b3b0; background: #fdf6f5; }
+.hctile.bad .s { color: var(--bad-ink); }
+@media (max-width: 640px) { .hctiles { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
 
 /* activity */
 .ev { display: flex; gap: 12px; padding: 10px 0; border-bottom: 1px solid var(--line-2); font-size: 13px; }

app.js

@@ -257,13 +257,26 @@
     else if (okMsg) toast(okMsg);
   }
 
+  // dialog shows a modal dialog. Extensions such as Bitwarden move elements
+  // around in <body>; a moved dialog stays open but drops out of the top
+  // layer to the bottom of the page, so it is shown as a modal again. That
+  // goes through close(), whose close event arrives after the dialog is open
+  // again and is kept from the listeners added by callers.
   function dialog(build) {
     const d = h('dialog');
     const close = () => d.close();
-    d.addEventListener('close', () => d.remove());
+    const moved = new MutationObserver(() => {
+      if (d.open && d.isConnected && !d.matches(':modal')) { d.close(); d.showModal(); }
+    });
+    d.addEventListener('close', (e) => {
+      if (d.open) { e.stopImmediatePropagation(); return; }
+      moved.disconnect();
+      d.remove();
+    });
     d.append(build(close));
     document.body.append(d);
     d.showModal();
+    moved.observe(document.body, { childList: true, subtree: true });
     return d;
   }
 
@@ -1111,7 +1124,7 @@
         return hit && keep;
       });
       tbody.replaceChildren(...sorted(rows).map((p) => h('tr', null,
-        h('td', null, h('a', { href: '#/peers/' + p.id }, h('strong', null, p.name)), p.note ? h('div', { class: 'note' }, p.note) : null),
+        h('td', null, h('a', { class: 'pname', href: '#/peers/' + p.id }, p.name), p.note ? h('div', { class: 'note' }, p.note) : null),
         h('td', { class: 'mono' }, p.ipv4),
         h('td', null, badge(peerState(p))),
         h('td', { class: 'mono muted' }, p.stats.endpoint || '–',
@@ -1497,6 +1510,69 @@
 
   const DNS_PRESETS = [['Quad9', '9.9.9.9, 149.112.112.112']];
 
+  // healthParts turns the server's checks into the Health card: the public
+  // address per IP family (from its uplink and public address checks), then
+  // one tile per other check with a plain-word status, the raw setting and,
+  // when it fails, what is wrong.
+  function healthParts(checks) {
+    const by = Object.fromEntries(checks.map((c) => [c.name, c]));
+    const addrs = [];
+    for (const fam of ['IPv4', 'IPv6']) {
+      const up = by[fam + ' uplink'], pub = by['Public ' + fam];
+      if (!up) continue;
+      const m = pub && pub.ok ? /^(\S+) \((.+)\)$/.exec(pub.detail) : null;
+      addrs.push({
+        label: 'Public ' + fam + (up.ok ? ' · ' + up.detail : ''),
+        ok: up.ok && (!pub || pub.ok),
+        value: m ? m[1] : (pub ? pub.detail : up.detail),
+        note: m ? m[2] : null,
+        mono: !!(pub && pub.ok),
+      });
+    }
+    const sysctl = (d) => d.replace(/^net\.ipv[46]\.(conf\.)?/, '');
+    const tiles = checks.filter((c) => !/^(IPv[46] uplink|Public IPv[46])$/.test(c.name)).map((c) => {
+      const t = { label: c.name, ok: c.ok, status: c.ok ? 'OK' : 'Problem', raw: null, problem: c.ok ? null : c.detail };
+      switch (c.name) {
+        case 'WireGuard interface': t.status = c.detail; t.problem = null; break;
+        case 'IPv4 forwarding': case 'IPv6 forwarding': t.status = c.ok ? 'On' : 'Off'; t.raw = sysctl(c.detail); t.problem = null; break;
+        case 'IPv6 router announcements': {
+          const [setting, ...why] = c.detail.split(': ');
+          t.label = 'Router announcements';
+          t.status = !c.ok ? 'Ignored' : setting.endsWith('=0') ? 'Not used' : 'Accepted';
+          t.raw = sysctl(setting);
+          t.problem = c.ok || !why.length ? null : why.join(': ');
+          break;
+        }
+        case 'nftables rules':
+          t.status = c.ok ? 'Present' : 'Missing';
+          if (/^table /.test(c.detail)) { t.raw = c.detail.replace(/ (present|missing)$/, ''); t.problem = null; }
+          break;
+        case 'Last apply':
+          if (c.ok) { const iso = c.detail.replace(/^applied /, ''); t.status = ago(iso); t.title = fmtStamp(iso); } else t.status = 'Failed';
+          break;
+        case 'Latency check': t.status = c.ok ? 'Tunnel ping works' : 'Failing'; break;
+      }
+      return t;
+    });
+    return { addrs, tiles, failing: checks.filter((c) => !c.ok).length, total: checks.length };
+  }
+
+  function healthCard(checks) {
+    const hp = healthParts(checks);
+    const dot = (ok) => [h('span', { class: ok ? 'dot ok' : 'dot bad' }), h('span', { class: 'sr' }, ok ? 'OK: ' : 'Problem: ')];
+    return h('section', { class: 'card', 'aria-labelledby': 'hc' },
+      h('div', { class: 'hchead' }, h('h2', { id: 'hc' }, 'Health'),
+        h('span', { class: hp.failing ? 'bad' : null }, hp.failing ? hp.failing + ' of ' + hp.total + ' checks failing' : 'All ' + hp.total + ' checks pass')),
+      hp.addrs.length ? h('div', { class: 'hcaddrs' }, hp.addrs.map((a) => h('div', { class: a.ok ? 'hcaddr' : 'hcaddr bad' },
+        h('div', { class: 'l' }, dot(a.ok), a.label),
+        h('div', { class: a.mono ? 'v mono' : 'v' }, a.value, a.note ? h('span', { class: 'n' }, ' ' + a.note) : null)))) : null,
+      h('div', { class: 'hctiles' }, hp.tiles.map((t) => h('div', { class: t.ok ? 'hctile' : 'hctile bad', title: t.title || null },
+        h('div', { class: 'l' }, h('span', null, t.label), dot(t.ok)),
+        h('div', { class: 's' }, t.status),
+        t.raw ? h('div', { class: 'r mono' }, t.raw) : null,
+        t.problem ? h('div', { class: 'p' }, t.problem) : null))));
+  }
+
   async function viewServer(wrap) {
     const [srv, st] = await Promise.all([api('GET', '/server'), api('GET', '/status')]);
     const orig = JSON.parse(JSON.stringify(srv));
@@ -1567,11 +1643,7 @@
     fill(wrap,
       h('div', null, h('h1', null, 'Server'), h('p', { class: 'sub' }, 'WireGuard interface, address plan, client defaults and firewall')),
       result,
-      h('section', { class: 'card', 'aria-labelledby': 'hc' },
+      healthCard(st.checks),
-        h('h2', { id: 'hc' }, 'Health'),
-        h('div', { style: { marginTop: '8px' } }, st.checks.map((c) => h('div', { class: 'chk' },
-          h('span', { class: c.ok ? 'dot ok' : 'dot bad' }), h('span', { class: 'sr' }, c.ok ? 'OK: ' : 'Problem: '),
-          h('b', null, c.name), h('span', { class: c.ok ? 'muted' : null }, c.detail))))),
 
       h('section', { class: 'card', 'aria-labelledby': 'if' },
         h('h2', { id: 'if' }, 'Interface'),

auth.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"net/netip"
 	"strings"
 	"sync"
 	"time"
@@ -26,12 +27,23 @@ const (
 	argonKeyLen  = 32
 )
 
+// Every argon2 run takes argonMemory (64 MiB). argonSlots caps how many run
+// at once, so a burst of sign-ins cannot run the server out of memory: two
+// slots are 128 MiB at most.
+var argonSlots = make(chan struct{}, 2)
+
+func argonKey(pw, salt []byte, t, m uint32, p uint8, n uint32) []byte {
+	argonSlots <- struct{}{}
+	defer func() { <-argonSlots }()
+	return argon2.IDKey(pw, salt, t, m, p, n)
+}
+
 func hashPassword(pw string) (string, error) {
 	salt := make([]byte, 16)
 	if _, err := rand.Read(salt); err != nil {
 		return "", err
 	}
-	key := argon2.IDKey([]byte(pw), salt, argonTime, argonMemory, argonThreads, argonKeyLen)
+	key := argonKey([]byte(pw), salt, argonTime, argonMemory, argonThreads, argonKeyLen)
 	b64 := base64.RawStdEncoding
 	return fmt.Sprintf("$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s",
 		argon2.Version, argonMemory, argonTime, argonThreads, b64.EncodeToString(salt), b64.EncodeToString(key)), nil
@@ -54,7 +66,7 @@ func verifyPassword(encoded, pw string) bool {
 	if err1 != nil || err2 != nil {
 		return false
 	}
-	got := argon2.IDKey([]byte(pw), salt, t, m, p, uint32(len(want)))
+	got := argonKey([]byte(pw), salt, t, m, p, uint32(len(want)))
 	return subtle.ConstantTimeCompare(got, want) == 1
 }
 
@@ -139,14 +151,18 @@ type Auth struct {
 	mu       sync.Mutex
 	sessions map[string]*session
 	used     map[string]tokenUse
-	logins   map[string]tokenUse // last sign-in per user ID
+	logins   map[string]tokenUse   // last sign-in per user ID
-	fails    map[string]*failState
+	fails    map[string]*failState // by lockKey
+	waiting  int                   // sign-ins waiting for or running a password check
 	mfa      mfaState
 }
 
 const (
 	maxFailures = 5
 	lockoutTime = 15 * time.Minute
+	// maxWaiting sign-ins may wait for a password check; more are turned
+	// away until the queue is shorter.
+	maxWaiting = 16
 )
 
 func newAuth(s *Store) *Auth {
@@ -155,23 +171,51 @@ func newAuth(s *Store) *Auth {
 
 func cookieName() string { return appName + "_session" }
 
-var errLocked = errors.New("too many failed attempts, try again later")
+var (
+	errLocked = errors.New("too many failed attempts, try again later")
+	errBusy   = errors.New("too many sign-ins at once, try again in a moment")
+)
+
+// lockKey is what failed sign-ins are counted by: the IPv4 address, or the
+// /64 network of an IPv6 address, since one device can pick any address in
+// its /64.
+func lockKey(ip string) string {
+	a, err := netip.ParseAddr(ip)
+	if err != nil || a.Unmap().Is4() {
+		return ip
+	}
+	p, _ := a.Prefix(64)
+	return p.String()
+}
 
 // Login checks the credentials and returns a new session id, or, for a user
 // with two-step sign-in, a ticket for the second step.
 func (a *Auth) Login(user, pw, ip string) (sessionID, ticket string, err error) {
-	a.mu.Lock()
-	f := a.fails[ip]
-	if f != nil && time.Now().Before(f.until) {
-		a.mu.Unlock()
-		return "", "", errLocked
-	}
-	a.mu.Unlock()
-
 	cfg := a.store.Get()
 	if !cfg.passwordSet() {
 		return "", "", errors.New("no password is set; run: " + appName + " passwd")
 	}
+	// The attempt counts as failed before the password is checked, so
+	// parallel attempts cannot get past the lockout; a right password takes
+	// it back.
+	a.mu.Lock()
+	if a.lockedLocked(ip) {
+		a.mu.Unlock()
+		return "", "", errLocked
+	}
+	if a.waiting >= maxWaiting {
+		a.mu.Unlock()
+		return "", "", errBusy
+	}
+	a.waiting++
+	undo := a.failLocked(ip)
+	a.mu.Unlock()
+	defer func() {
+		a.mu.Lock()
+		a.waiting--
+		a.mu.Unlock()
+	}()
+
 	// An unknown username costs as much time as a wrong password, so the
 	// answer time does not tell which usernames exist.
 	u := cfg.userByName(strings.TrimSpace(user))
@@ -185,21 +229,13 @@ func (a *Auth) Login(user, pw, ip string) (sessionID, ticket string, err error)
 	a.mu.Lock()
 	defer a.mu.Unlock()
 	if !okUser || !okPw {
-		if f == nil {
-			f = &failState{}
-			a.fails[ip] = f
-		}
-		f.count++
-		if f.count >= maxFailures {
-			f.count = 0
-			f.until = time.Now().Add(lockoutTime)
-		}
 		return "", "", errors.New("wrong username or password")
 	}
+	undo()
 	if u.hasMFA() {
 		return "", a.newTicketLocked(u, ip), nil
 	}
-	delete(a.fails, ip)
+	delete(a.fails, lockKey(ip))
 	a.logins[u.ID] = tokenUse{At: time.Now(), IP: ip}
 	return a.newSessionLocked(cfg, u, sessionInfo{Started: time.Now(), IP: ip}), "", nil
 }
@@ -321,9 +357,9 @@ func (a *Auth) sweep() {
 			delete(a.sessions, id)
 		}
 	}
-	for ip, f := range a.fails {
+	for key, f := range a.fails {
 		if now.After(f.until) && f.count == 0 {
-			delete(a.fails, ip)
+			delete(a.fails, key)
 		}
 	}
 	for id, t := range a.mfa.tickets {

kernel.go

@@ -3,6 +3,8 @@ package main
 import (
 	"log/slog"
 	"net/netip"
+	"os"
+	"strings"
 	"sync"
 	"time"
 )
@@ -38,6 +40,15 @@ type Kernel interface {
 	Close() error
 }
 
+// readSysctl returns the trimmed content of a /proc/sys file, or "".
+func readSysctl(path string) string {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	return strings.TrimSpace(string(b))
+}
+
 // Reconciler applies the config to the kernel whenever it is triggered and
 // remembers the outcome for the health report.
 type Reconciler struct {

kernel_linux.go

@@ -3,13 +3,13 @@
 package main
 
 import (
+	"cmp"
 	"errors"
 	"fmt"
 	"net"
 	"net/netip"
 	"os"
 	"slices"
-	"strings"
 
 	"github.com/vishvananda/netlink"
 	"golang.zx2c4.com/wireguard/wgctrl"
@@ -318,14 +318,6 @@ func publicAddr(uplink string, v6 bool) (bool, string) {
 	return false, "no address on " + uplink
 }
 
-func readSysctl(path string) string {
-	b, err := os.ReadFile(path)
-	if err != nil {
-		return ""
-	}
-	return strings.TrimSpace(string(b))
-}
-
 func (k *linuxKernel) Checks(c *Config) []Check {
 	var out []Check
 	link, err := netlink.LinkByName(c.Server.Interface)
@@ -341,6 +333,19 @@ func (k *linuxKernel) Checks(c *Config) []Check {
 		v := readSysctl("/proc/sys/net/ipv6/conf/all/forwarding")
 		out = append(out, Check{"IPv6 forwarding", v == "1", "net.ipv6.conf.all.forwarding=" + v})
 	}
+	// With IPv6 forwarding on, accept_ra 1 means router announcements are
+	// ignored: an IPv6 route learned from them expires (see sysctlConf).
+	if readSysctl("/proc/sys/net/ipv6/conf/all/forwarding") == "1" {
+		up := cmp.Or(k.Uplink(c, true), k.Uplink(c, false))
+		if ra := readSysctl("/proc/sys/net/ipv6/conf/" + up + "/accept_ra"); up != "" && ra != "" {
+			ok := ra != "1"
+			detail := "net.ipv6.conf." + up + ".accept_ra=" + ra
+			if !ok {
+				detail += ": IPv6 from router announcements stops working; run " + appName + " update"
+			}
+			out = append(out, Check{"IPv6 router announcements", ok, detail})
+		}
+	}
 	ok, detail := firewallPresent()
 	out = append(out, Check{"nftables rules", ok, detail})
 	up4 := k.Uplink(c, false)

main_test.go

@@ -12,7 +12,9 @@ import (
 	"net/netip"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 )
@@ -311,8 +313,13 @@ func TestAPI(t *testing.T) {
 	secret := tok["token"].(string)
 
 	// Read-only token: GET works, changes are refused, admin endpoints too.
-	bearer := func(method, path string, want int) {
+	bearer := func(method, path string, want int, body ...any) {
-		req, _ := http.NewRequest(method, srv.URL+"/api/v1"+path, nil)
+		var rd io.Reader
+		if len(body) > 0 {
+			b, _ := json.Marshal(body[0])
+			rd = bytes.NewReader(b)
+		}
+		req, _ := http.NewRequest(method, srv.URL+"/api/v1"+path, rd)
 		req.Header.Set("Authorization", "Bearer "+secret)
 		resp, err := http.DefaultClient.Do(req)
 		if err != nil {
@@ -328,10 +335,20 @@ func TestAPI(t *testing.T) {
 	bearer("GET", "/tokens", 403)
 	bearer("GET", "/peers/"+id+"/setup", 403) // the link would set up a device
 
-	// A full-access token manages users and tokens, but not backups.
+	// A full-access token changes settings, but users, passwords, tokens,
+	// the sign-in rules and backups need a signed-in user.
 	secret = call("POST", "/tokens", map[string]string{"name": "full", "scope": "rw"}, 201)["token"].(string)
-	bearer("GET", "/users", 200)
+	uid := call("GET", "/auth/me", nil, 200)["id"].(string)
-	bearer("GET", "/tokens", 200)
+	bearer("PATCH", "/settings", 200, map[string]any{"log": store.Get().Log})
+	bearer("PATCH", "/settings", 403, map[string]any{"signin": map[string]bool{"requireMfa": false}})
+	bearer("GET", "/users", 403)
+	bearer("POST", "/users", 403, map[string]any{"username": "eve", "password": "correct horse battery"})
+	bearer("POST", "/users/"+uid+"/reset-password", 403, map[string]any{"password": "correct horse battery"})
+	bearer("POST", "/users/"+uid+"/reset-mfa", 403)
+	bearer("POST", "/auth/password", 403, map[string]string{"current": "x", "new": "y"})
+	bearer("GET", "/tokens", 403)
+	bearer("POST", "/tokens", 403, map[string]string{"name": "more", "scope": "rw"})
+	bearer("DELETE", "/tokens/"+tok["id"].(string), 403)
 	bearer("GET", "/backup", 403)
 
 	call("DELETE", "/peers/"+id, nil, 200)
@@ -376,6 +393,92 @@ func TestUnitFile(t *testing.T) {
 	}
 }
 
+func TestSysctlConf(t *testing.T) {
+	dir := t.TempDir()
+	conf, sys := filepath.Join(dir, "conf"), filepath.Join(dir, "net")
+	for name, ra := range map[string]string{"eth0": "1", "wlan0": "2", "eth1": "0", "br0": "1", "veth1": "1", "lo": "1"} {
+		_ = os.MkdirAll(filepath.Join(conf, name), 0o755)
+		_ = os.WriteFile(filepath.Join(conf, name, "accept_ra"), []byte(ra+"\n"), 0o644)
+	}
+	for _, name := range []string{"eth0", "wlan0", "eth1"} { // network cards
+		_ = os.MkdirAll(filepath.Join(sys, name, "device"), 0o755)
+	}
+	_ = os.MkdirAll(filepath.Join(sys, "veth1"), 0o755)
+	// br0 carries the default route; the lo line is the kernel's unreachable route.
+	routes := filepath.Join(dir, "ipv6_route")
+	_ = os.WriteFile(routes, []byte(
+		"00000000000000000000000000000000 00 00000000000000000000000000000000 00 fe800000000000000000000000000001 00000400 00000001 00000000 00000003     br0\n"+
+			"00000000000000000000000000000000 00 00000000000000000000000000000000 00 00000000000000000000000000000000 ffffffff 00000001 00000000 00200200       lo\n"), 0o644)
+
+	got := raInterfaces(conf, sys, routes)
+	if want := []string{"br0", "eth0", "wlan0"}; !slices.Equal(got, want) {
+		t.Fatalf("raInterfaces = %v, want %v", got, want)
+	}
+	c := sysctlConf(got)
+	for _, want := range []string{"net.ipv6.conf.all.forwarding=1\n", "net.ipv6.conf.default.accept_ra=2\n", "net.ipv6.conf.eth0.accept_ra=2\n", "net.ipv6.conf.br0.accept_ra=2\n"} {
+		if !strings.Contains(c, want) {
+			t.Errorf("sysctl conf lacks %q:\n%s", want, c)
+		}
+	}
+	if strings.Contains(c, "eth1") || strings.Contains(c, "veth1") {
+		t.Errorf("sysctl conf names eth1 (accept_ra 0) or veth1 (virtual):\n%s", c)
+	}
+}
+
+func TestLoginLockout(t *testing.T) {
+	store, err := openStore(filepath.Join(t.TempDir(), "config.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	hash, _ := hashPassword("a long test password")
+	_ = store.Update(func(c *Config) error { c.Users[0].PasswordHash = hash; return nil })
+	a := newAuth(store)
+	const right, wrong = "a long test password", "a wrong password"
+
+	// Ten wrong attempts at once from one /64: five are checked, the others
+	// are locked out before any password check.
+	var wg sync.WaitGroup
+	var mu sync.Mutex
+	got := map[string]int{}
+	for i := range 10 {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			_, _, err := a.Login("admin", wrong, fmt.Sprintf("2001:db8::%x", i+1))
+			mu.Lock()
+			got[err.Error()]++
+			mu.Unlock()
+		}()
+	}
+	wg.Wait()
+	if got["wrong username or password"] != 5 || got[errLocked.Error()] != 5 {
+		t.Fatalf("parallel attempts: %v", got)
+	}
+	if _, _, err := a.Login("admin", right, "2001:db8::ffff"); !errors.Is(err, errLocked) {
+		t.Fatalf("same /64: %v, want locked", err)
+	}
+	if _, _, err := a.Login("admin", right, "2001:db8:0:1::1"); err != nil {
+		t.Fatalf("other /64: %v", err)
+	}
+
+	// A right password takes its own attempt back. With two-step sign-in
+	// the earlier failures stay, so wrong codes still lead to the lockout.
+	_ = store.Update(func(c *Config) error { c.Users[0].MFA = &UserMFA{TOTPSecret: newTOTPSecret()}; return nil })
+	ip := "192.0.2.7"
+	for range maxFailures - 1 {
+		_, _, _ = a.Login("admin", wrong, ip)
+	}
+	if _, tk, err := a.Login("admin", right, ip); err != nil || tk == "" {
+		t.Fatalf("5th attempt, right password: ticket %q, %v", tk, err)
+	}
+	if _, _, err := a.Login("admin", wrong, ip); err == nil || errors.Is(err, errLocked) {
+		t.Fatalf("6th attempt: %v, want wrong password", err)
+	}
+	if _, _, err := a.Login("admin", right, ip); !errors.Is(err, errLocked) {
+		t.Fatalf("7th attempt: %v, want locked", err)
+	}
+}
+
 func TestWriteIfChanged(t *testing.T) {
 	p := filepath.Join(t.TempDir(), "x.conf")
 	if ch, err := writeIfChanged(p, "a\n", 0o644); !ch || err != nil {
@@ -881,7 +984,6 @@ func TestUsers(t *testing.T) {
 	if n := len(admin("GET", "/users", nil, 200)["users"].([]any)); n != 2 {
 		t.Fatalf("users: %d, want 2", n)
 	}
-	admin("PATCH", "/settings", map[string]any{"adminUsername": "x"}, 400)
 }
 
 // TestDecoy checks that the decoy hides the web interface but leaves the API

mfa.go

@@ -236,23 +236,34 @@ func newMFAState() mfaState {
 
 var errBadTicket = errors.New("the sign-in expired; enter your password again")
 
-// failLocked counts a failed attempt from ip toward the lockout. a.mu must
+// failLocked counts a failed attempt from ip toward the lockout and returns
-// be held.
+// a function that takes it back, for an attempt counted before it was
-func (a *Auth) failLocked(ip string) {
+// checked. a.mu must be held, also when calling undo.
-	f := a.fails[ip]
+func (a *Auth) failLocked(ip string) (undo func()) {
+	key := lockKey(ip)
+	f := a.fails[key]
 	if f == nil {
 		f = &failState{}
-		a.fails[ip] = f
+		a.fails[key] = f
 	}
 	f.count++
-	if f.count >= maxFailures {
+	locked := f.count >= maxFailures
+	if locked {
 		f.count = 0
 		f.until = time.Now().Add(lockoutTime)
 	}
+	return func() {
+		switch {
+		case locked:
+			f.count, f.until = maxFailures-1, time.Time{}
+		case f.count > 0:
+			f.count--
+		}
+	}
 }
 
 func (a *Auth) lockedLocked(ip string) bool {
-	f := a.fails[ip]
+	f := a.fails[lockKey(ip)]
 	return f != nil && time.Now().Before(f.until)
 }
 
@@ -302,7 +313,7 @@ func (a *Auth) finishSignIn(u *User, ip string) string {
 	cfg := a.store.Get()
 	a.mu.Lock()
 	defer a.mu.Unlock()
-	delete(a.fails, ip)
+	delete(a.fails, lockKey(ip))
 	a.logins[u.ID] = tokenUse{At: time.Now(), IP: ip}
 	return a.newSessionLocked(cfg, u, sessionInfo{Started: time.Now(), IP: ip})
 }

setup.go

@@ -12,6 +12,7 @@ import (
 	"os/user"
 	"path/filepath"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
@@ -273,7 +274,51 @@ WantedBy=multi-user.target
 // rewrite the unit for every release.
 const unitVersion = "unit-1"
 
-const sysctlConf = "net.ipv4.ip_forward=1\nnet.ipv6.conf.all.forwarding=1\n"
+// sysctlConf turns on forwarding. With IPv6 forwarding on, Linux ignores
+// router announcements unless accept_ra is 2, and a server that gets its
+// IPv6 route from them (SLAAC, e.g. a Raspberry Pi at home) loses IPv6 when
+// the route expires. So every interface in ras keeps accepting them, as
+// pivpn does for its uplink.
+func sysctlConf(ras []string) string {
+	var b strings.Builder
+	b.WriteString("net.ipv4.ip_forward=1\nnet.ipv6.conf.all.forwarding=1\nnet.ipv6.conf.default.accept_ra=2\n")
+	for _, name := range ras {
+		fmt.Fprintf(&b, "net.ipv6.conf.%s.accept_ra=2\n", name)
+	}
+	return b.String()
+}
+
+// raInterfaces returns the network cards and the interface of the IPv6
+// default route, except those where router announcements are switched off
+// (accept_ra 0). The directories are /proc/sys/net/ipv6/conf and
+// /sys/class/net, routes is /proc/net/ipv6_route.
+func raInterfaces(confDir, netDir, routes string) []string {
+	want := map[string]bool{}
+	if b, err := os.ReadFile(routes); err == nil {
+		for _, line := range strings.Split(string(b), "\n") {
+			f := strings.Fields(line)
+			if len(f) == 10 && f[0] == strings.Repeat("0", 32) && f[1] == "00" && f[9] != "lo" {
+				want[f[9]] = true
+			}
+		}
+	}
+	entries, _ := os.ReadDir(netDir)
+	for _, e := range entries {
+		// Only real devices: bridges, veth and tunnels come and go.
+		if _, err := os.Stat(filepath.Join(netDir, e.Name(), "device")); err == nil {
+			want[e.Name()] = true
+		}
+	}
+	var out []string
+	for name := range want {
+		v := readSysctl(filepath.Join(confDir, name, "accept_ra"))
+		if v == "1" || v == "2" {
+			out = append(out, name)
+		}
+	}
+	slices.Sort(out)
+	return out
+}
 
 // writeSystemFiles writes the unit, sysctl and module files. It reports
 // whether the unit changed (systemd must then reload).
@@ -281,7 +326,8 @@ func writeSystemFiles() (unitChanged bool, err error) {
 	if unitChanged, err = writeIfChanged(unitPath, unitFile(), 0o644); err != nil {
 		return false, err
 	}
-	sysChanged, err := writeIfChanged(sysctlPath, sysctlConf, 0o644)
+	ras := raInterfaces("/proc/sys/net/ipv6/conf", "/sys/class/net", "/proc/net/ipv6_route")
+	sysChanged, err := writeIfChanged(sysctlPath, sysctlConf(ras), 0o644)
 	if err != nil {
 		return false, err
 	}