Internet exposure checks and response rate limiting

Jarl works out which views are reachable from the internet (match-clients
ending in a catch-all, not private-looking addresses: an internal view of a
global IPv6 prefix is still yours; a server without views: open allow-query
and a non-private listen address), with a per-view override (schema 9), and
checks public ones: rate limiting, open resolver, minimal-any, cache
snooping, open NOTIFY and transfers, version and host name, management
interfaces. Fixes are staged like any change, including rate limiting from
ISC's example in log-only mode with the secondaries exempt, then enforcing.
named logs what rate limiting limits (or would, in log-only mode, where its
counters don't move) as query-errors; Jarl routes those lines to its log
and counts them (rrl breakdown, ratelimited top lists, Prometheus
jarl_ratelimit_logged_total), shown on the new Exposure page.

A change that newly opens a public view up must be confirmed (accept_risk,
--accept-risk, a checkbox on the Changes page; 409 confirm_risk
otherwise). Findings can be acknowledged with a reason and stay visible as
info. GET /exposure, POST /exposure/fix|ack|unack, jarl exposure,
docs/exposure.md.

Also fixes query statistics skipping TSIG-signed queries ("IP#port/key
NAME" in named's log).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/engine/diffops.go

@@ -3,6 +3,7 @@ package engine
 import (
 	"fmt"
 	"reflect"
+	"slices"
 	"sort"
 
 	"jarl/internal/dnsname"
@@ -23,7 +24,8 @@ func DiffOps(from, to *model.State) []model.Op {
 	if !reflect.DeepEqual(stripVersion(from.Settings), stripVersion(to.Settings)) {
 		s := to.Settings
 		add(OpSettingsUpdate, 0, 0, SettingsInput{DefaultTTL: &s.DefaultTTL, Nameservers: model.Ptr(append([]string{}, s.Nameservers...)), RName: &s.RName,
-			Refresh: &s.Refresh, Retry: &s.Retry, Expire: &s.Expire, NegativeTTL: &s.NegativeTTL, SerialPolicy: &s.SerialPolicy}, "restore settings")
+			Refresh: &s.Refresh, Retry: &s.Retry, Expire: &s.Expire, NegativeTTL: &s.NegativeTTL, SerialPolicy: &s.SerialPolicy,
+			Exposure: &s.Exposure, Acknowledged: model.Ptr(slices.Clone(s.Acknowledged))}, "restore settings")
 	}
 
 	for _, k := range sortedKeys(to.Keys) {
@@ -47,7 +49,8 @@ func DiffOps(from, to *model.State) []model.Op {
 	for _, k := range sortedKeys(to.Views) {
 		n := to.Views[k]
 		in := ViewInput{Name: &n.Name, MatchClients: model.Ptr(append([]string{}, n.MatchClients...)),
-			MatchDestinations: model.Ptr(append([]string{}, n.MatchDestinations...)), Comment: &n.Comment, Position: model.Ptr(n.Position)}
+			MatchDestinations: model.Ptr(append([]string{}, n.MatchDestinations...)), Comment: &n.Comment, Position: model.Ptr(n.Position),
+			Exposure: model.Ptr(n.Exposure), Acknowledged: model.Ptr(slices.Clone(n.Acknowledged))}
 		if n.MatchRecursiveOnly != nil {
 			in.MatchRecursiveOnly = model.Some(*n.MatchRecursiveOnly)
 		} else {

internal/engine/engine.go

@@ -15,6 +15,7 @@ import (
 	"io/fs"
 	"log/slog"
 	"net/http"
+	"net/netip"
 	"os"
 	"path/filepath"
 	"slices"
@@ -56,6 +57,10 @@ type Config struct {
 	NoReload bool
 	// SkipCheck disables named-checkconf (only for tests without BIND).
 	SkipCheck bool
+	// LocalAddrs returns this host's addresses, for working out whether a
+	// server without views is reachable from the internet
+	// (docs/exposure.md). nil: none known.
+	LocalAddrs func() []netip.Addr
 }
 
 // Engine applies changesets.
@@ -110,17 +115,20 @@ type Result struct {
 	DryRun      bool               `json:"dry_run,omitempty"`
 	Valid       bool               `json:"valid"`
 	Problems    []validate.Problem `json:"problems"` // problems this change introduces
-	Existing    []validate.Problem `json:"existing_problems,omitempty"`
-	Check       []CheckMessage     `json:"check,omitempty"`
-	CheckOK     bool               `json:"check_ok"`
-	Diff        string             `json:"diff"`
-	Files       []string           `json:"files_changed"`
-	Serials     []SerialChange     `json:"serials,omitempty"`
-	Reloaded    []string           `json:"reloaded,omitempty"`
-	Warnings    []string           `json:"warnings,omitempty"`
-	Drift       []DriftEntry       `json:"drift,omitempty"`
-	Ops         []model.Op         `json:"ops,omitempty"`
-	Error       *Error             `json:"error,omitempty"`
+	// Risks are the introduced problems that open the server up; applying
+	// needs AcceptRisk (docs/exposure.md).
+	Risks    []validate.Problem `json:"risks,omitempty"`
+	Existing []validate.Problem `json:"existing_problems,omitempty"`
+	Check    []CheckMessage     `json:"check,omitempty"`
+	CheckOK  bool               `json:"check_ok"`
+	Diff     string             `json:"diff"`
+	Files    []string           `json:"files_changed"`
+	Serials  []SerialChange     `json:"serials,omitempty"`
+	Reloaded []string           `json:"reloaded,omitempty"`
+	Warnings []string           `json:"warnings,omitempty"`
+	Drift    []DriftEntry       `json:"drift,omitempty"`
+	Ops      []model.Op         `json:"ops,omitempty"`
+	Error    *Error             `json:"error,omitempty"`
 }
 
 // stored is what is kept in a changeset's result column.
@@ -138,6 +146,9 @@ type ApplyOptions struct {
 	Force bool
 	// NoReload writes the files without reloading named.
 	NoReload bool
+	// AcceptRisk confirms a change that opens the server up, such as an
+	// open resolver on a public view (validate.RiskCodes).
+	AcceptRisk bool
 	// wipeZone lets WipeDNSSEC switch signing off for this zone at once.
 	wipeZone int64
 }
@@ -180,7 +191,46 @@ func ValidateOptions(st *model.State) validate.Options {
 }
 
 func (e *Engine) validate(st *model.State) []validate.Problem {
-	return validate.State(st, ValidateOptions(st))
+	return validate.State(st, e.validateOptions(st))
+}
+
+func (e *Engine) validateOptions(st *model.State) validate.Options {
+	opts := ValidateOptions(st)
+	if e.cfg.LocalAddrs != nil {
+		opts.LocalAddrs = e.cfg.LocalAddrs()
+	}
+	return opts
+}
+
+// Validate checks a state as applying it would.
+func (e *Engine) Validate(st *model.State) []validate.Problem { return e.validate(st) }
+
+// Exposures says which views (or the server, without views) are
+// reachable from the internet, and why (docs/exposure.md).
+func (e *Engine) Exposures(st *model.State) []validate.Exposure {
+	return validate.Exposures(st, e.validateOptions(st))
+}
+
+// risks returns the introduced problems that open a public view (or a
+// public server) up: risky warnings that weren't there before at all. One
+// that was there already, acknowledged (taking the acknowledgement back)
+// or not, opens nothing new.
+func risks(before, introduced []validate.Problem, public map[string]bool) []validate.Problem {
+	type key struct {
+		code, objType, view string
+		id                  int64
+	}
+	had := map[key]bool{}
+	for _, p := range before {
+		had[key{p.Code, p.ObjectType, p.View, p.ObjectID}] = true
+	}
+	var out []validate.Problem
+	for _, p := range introduced {
+		if p.Severity == validate.Warning && validate.RiskCodes[p.Code] && public[p.View] && !had[key{p.Code, p.ObjectType, p.View, p.ObjectID}] {
+			out = append(out, p)
+		}
+	}
+	return out
 }
 
 // ---- changeset management
@@ -389,6 +439,8 @@ type plan struct {
 	base, work    *model.State
 	introduced    []validate.Problem
 	existing      []validate.Problem
+	before        []validate.Problem // the problems before the change
+	public        map[string]bool    // public views by name ("": the server), after the change
 	serials       []SerialChange
 	out           *render.Output
 	changed       []*render.File
@@ -419,6 +471,13 @@ func (pl *plan) files() []string {
 func (e *Engine) makePlan(ctx context.Context, base, work *model.State, user string, opts ApplyOptions) (*plan, error) {
 	pl := &plan{base: base, work: work, verify: map[int64]uint32{}}
 	before := e.validate(base)
+	pl.before = before
+	pl.public = map[string]bool{}
+	for _, x := range e.Exposures(work) {
+		pl.public[x.View] = x.Public
+		// Server-wide findings (no view) count when anything is public.
+		pl.public[""] = pl.public[""] || x.Public
+	}
 	after := e.validate(work)
 	pl.introduced = append(validate.Introduced(before, after), e.dnssecChanges(base, work, opts)...)
 	introducedKeys := map[string]bool{}
@@ -652,6 +711,7 @@ func (pl *plan) result() *Result {
 		Files:    pl.files(),
 		Serials:  pl.serials,
 		Drift:    pl.drift,
+		Risks:    risks(pl.before, pl.introduced, pl.public),
 	}
 	r.Valid = r.Valid && r.CheckOK
 	if r.Files == nil {
@@ -781,6 +841,13 @@ func (e *Engine) applyOps(ctx context.Context, cs *model.Changeset, reqs []Reque
 	if opts.DryRun {
 		return res, nil
 	}
+	if rs := risks(pl.before, pl.introduced, pl.public); len(rs) > 0 && !opts.AcceptRisk {
+		msg := rs[0].Message
+		if len(rs) > 1 {
+			msg += fmt.Sprintf(" (and %d more)", len(rs)-1)
+		}
+		return res, &Error{Kind: KindRisk, Message: "this change opens the server up: " + msg + "; apply it again with accept_risk to confirm (jarl: --accept-risk), or acknowledge the finding for good", Problems: rs}
+	}
 	if len(pl.drift) > 0 && !opts.Force {
 		var paths []string
 		for _, d := range pl.drift {

internal/engine/errors.go

@@ -21,6 +21,7 @@ const (
 	KindBIND       ErrorKind = "bind_failed"       // named-checkconf or rndc failed
 	KindDrift      ErrorKind = "drift"             // files were changed outside Jarl
 	KindNotAdopted ErrorKind = "not_adopted"       // named does not load Jarl's config yet
+	KindRisk       ErrorKind = "confirm_risk"      // the change opens the server up and needs confirming
 )
 
 // Error is an engine error with details for the caller.

internal/engine/expand.go

@@ -228,6 +228,8 @@ func (x *expander) expand(req Request) ([]model.Op, error) {
 		return []model.Op{x.versioned(req, o.Version, summary)}, nil
 	case OpSettingsUpdate:
 		return []model.Op{newOpRaw(OpSettingsUpdate, 0, 0, req.Data, "update settings")}, nil
+	case OpExposureAck, OpExposureUnack:
+		return x.exposureAck(req, req.Op == OpExposureAck)
 	case OpBlocklistCreate:
 		return x.blocklistCreate(req)
 	case OpBlocklistUpdate, OpBlocklistDelete:
@@ -1089,3 +1091,64 @@ func disabledZoneEffect(st *model.State, z *model.Zone) string {
 	}
 	return fmt.Sprintf("once zone %s is disabled, %s answers REFUSED for its names", dnsname.Display(z.Name), where)
 }
+
+// exposureAck acknowledges an exposure finding of a view or the server,
+// or takes the acknowledgement back: the view's (or the settings')
+// acknowledgements are updated as a whole.
+func (x *expander) exposureAck(req Request, ack bool) ([]model.Op, error) {
+	var in AckInput
+	if err := decode(req.Data, &in); err != nil {
+		return nil, err
+	}
+	in.Code = strings.TrimSpace(in.Code)
+	if !validate.Ackable(in.Code) {
+		return nil, errf(KindBadRequest, "%q is not an exposure finding that can be acknowledged (exposure_... or security_open_...)", in.Code)
+	}
+	if ack && strings.TrimSpace(in.Reason) == "" {
+		return nil, errf(KindBadRequest, "say why %s is accepted (a reason is required)", in.Code)
+	}
+	var v *model.View
+	switch {
+	case in.ViewID != 0:
+		v = x.st.Views[in.ViewID]
+	case in.View != "":
+		v = x.st.ViewByName(in.View)
+	}
+	if (in.ViewID != 0 || in.View != "") && v == nil {
+		return nil, errf(KindNotFound, "no view %s", firstNonEmptyStr(in.View, fmt.Sprint(in.ViewID)))
+	}
+	acks := x.st.Settings.Acknowledged
+	where := "the server"
+	if v != nil {
+		acks, where = v.Acknowledged, "view "+v.Name
+	}
+	var out []model.Acknowledgement
+	for _, a := range acks {
+		if a.Code != in.Code {
+			out = append(out, a)
+		}
+	}
+	summary := "acknowledge " + in.Code + " for " + where + ": " + strings.TrimSpace(in.Reason)
+	if ack {
+		out = append(out, model.Acknowledgement{Code: in.Code, Reason: strings.TrimSpace(in.Reason), By: x.p.Name(), At: x.now})
+	} else {
+		if len(out) == len(acks) {
+			return nil, errf(KindConflict, "%s isn't acknowledged for %s", in.Code, where)
+		}
+		summary = "take back the acknowledgement of " + in.Code + " for " + where
+	}
+	if out == nil {
+		out = []model.Acknowledgement{}
+	}
+	if v != nil {
+		return []model.Op{newOp(OpViewUpdate, v.ID, v.Version, ViewInput{Acknowledged: &out}, summary)}, nil
+	}
+	return []model.Op{newOp(OpSettingsUpdate, 0, 0, SettingsInput{Acknowledged: &out}, summary)}, nil
+}
+
+func firstNonEmptyStr(a, b string) string {
+	if a != "" {
+		return a
+	}
+	return b
+}

internal/engine/exposure.go

@@ -0,0 +1,163 @@
+package engine
+
+import (
+	"net/netip"
+	"slices"
+	"strings"
+
+	"jarl/internal/model"
+	"jarl/internal/namedconf"
+)
+
+// ExposureFix returns the requests that fix an exposure finding of a view
+// (viewID 0: the server), and what they do, or nil when there is no
+// automatic fix: what to allow instead (your secondaries, your hosts)
+// is for you to decide. The requests go through a changeset like any
+// edit (docs/exposure.md).
+func ExposureFix(st *model.State, viewID int64, code string) ([]Request, string) {
+	v := st.Views[viewID]
+	scope, scopeID := model.ScopeOptions, int64(0)
+	if v != nil {
+		scope, scopeID = model.ScopeView, v.ID
+	}
+	set := func(name, value string) Request {
+		if o := st.FindOption(scope, scopeID, name); o != nil {
+			return NewRequest(OpOptionUpdate, o.ID, OptionInput{Value: &value})
+		}
+		return NewRequest(OpOptionCreate, 0, OptionInput{Scope: &scope, ScopeID: &scopeID, Name: &name, Value: &value})
+	}
+	server := func(name, value string) Request {
+		if o := st.FindOption(model.ScopeOptions, 0, name); o != nil {
+			return NewRequest(OpOptionUpdate, o.ID, OptionInput{Value: &value})
+		}
+		return NewRequest(OpOptionCreate, 0, OptionInput{Scope: model.Ptr(model.ScopeOptions), Name: &name, Value: &value})
+	}
+	switch code {
+	case "exposure_rate_limit":
+		value := RecommendedRateLimit(st, v)
+		return []Request{set("rate-limit", value)}, "start rate limiting in log-only mode: rate-limit " + value
+	case "exposure_rate_limit_log_only":
+		o := st.FindOption(scope, scopeID, "rate-limit")
+		if o == nil {
+			o = st.FindOption(model.ScopeOptions, 0, "rate-limit")
+		}
+		if o == nil {
+			return nil, ""
+		}
+		value := withoutLogOnly(o.Value)
+		return []Request{NewRequest(OpOptionUpdate, o.ID, OptionInput{Value: &value})}, "start enforcing the rate limit: rate-limit " + value
+	case "exposure_minimal_any":
+		return []Request{set("minimal-any", "yes")}, "answer ANY queries minimally: minimal-any yes"
+	case "exposure_cache_snooping":
+		return []Request{set("allow-query-cache", "{ none; }")}, "close the cache to everyone: allow-query-cache { none; }"
+	case "exposure_version":
+		return []Request{server("version", "none")}, "hide BIND's version: version none"
+	case "exposure_hostname":
+		return []Request{server("hostname", "none")}, "hide the host name: hostname none"
+	case "security_open_resolver":
+		if v == nil {
+			return nil, "" // a server without views is also your own resolver
+		}
+		return []Request{set("recursion", "no")}, "turn recursion off in view " + v.Name + ": recursion no"
+	}
+	return nil, ""
+}
+
+// RecommendedRateLimit is the rate-limit block Jarl suggests for a public
+// view (v nil: the server): ISC's example of 10 identical responses per
+// second per client network, in log-only mode until you have looked at
+// what it would limit, with your secondaries exempt so zone transfers
+// and their queries are never limited.
+func RecommendedRateLimit(st *model.State, v *model.View) string {
+	parts := []string{"responses-per-second 10;", "log-only yes;"}
+	if ex := secondaries(st, v); len(ex) > 0 {
+		parts = append(parts, "exempt-clients { "+strings.Join(ex, "; ")+"; };")
+	}
+	return "{ " + strings.Join(parts, " ") + " }"
+}
+
+// secondaries returns the addresses the view's zones notify and allow
+// transfers to (ACLs resolved), the servers that rate limiting must leave
+// alone.
+func secondaries(st *model.State, v *model.View) []string {
+	var opts []*model.Option
+	add := func(scope string, id int64) {
+		for _, name := range []string{"also-notify", "allow-transfer"} {
+			if o := st.FindOption(scope, id, name); o != nil {
+				opts = append(opts, o)
+			}
+		}
+	}
+	add(model.ScopeOptions, 0)
+	vid := int64(0)
+	if v != nil {
+		vid = v.ID
+		add(model.ScopeView, v.ID)
+	}
+	for _, z := range st.SortedZones() {
+		if z.ViewID == vid {
+			add(model.ScopeZone, z.ID)
+		}
+	}
+	seen := map[string]bool{}
+	var out []string
+	var addElems func(list []string, depth int)
+	addElems = func(list []string, depth int) {
+		for _, s := range list {
+			e, err := namedconf.ParseAMElement(s)
+			if err != nil || e.Negated {
+				continue
+			}
+			switch e.Kind {
+			case namedconf.AMPrefix, namedconf.AMRange:
+				if t := e.String(); !seen[t] {
+					seen[t] = true
+					out = append(out, t)
+				}
+			case namedconf.AMName:
+				if a := st.ACLByName(e.Name); a != nil && depth < 10 {
+					addElems(a.Elements, depth+1)
+				}
+			}
+		}
+	}
+	for _, o := range opts {
+		stmt, err := namedconf.ParseOptionValue(o.Name, o.Value)
+		if err != nil || stmt.FirstBlock() == nil {
+			continue
+		}
+		var list []string
+		for _, s := range stmt.FirstBlock().Stmts {
+			if o.Name == "also-notify" {
+				// "ADDRESS [port N] [key K]": the address only.
+				if len(s.Items) > 0 && s.Items[0].Value != nil {
+					if _, err := netip.ParseAddr(s.Items[0].Value.Text); err == nil {
+						list = append(list, s.Items[0].Value.Text)
+					}
+				}
+				continue
+			}
+			list = append(list, namedconf.Compact(s.Items))
+		}
+		addElems(list, 0)
+	}
+	slices.Sort(out)
+	return out
+}
+
+// withoutLogOnly removes "log-only ...;" from a rate-limit block.
+func withoutLogOnly(value string) string {
+	st, err := namedconf.ParseOptionValue("rate-limit", value)
+	if err != nil || st.FirstBlock() == nil {
+		return value
+	}
+	b := st.FirstBlock()
+	var keep []*namedconf.Stmt
+	for _, s := range b.Stmts {
+		if s.Keyword() != "log-only" {
+			keep = append(keep, s)
+		}
+	}
+	b.Stmts = keep
+	return namedconf.Compact(st.Items[1:])
+}

internal/engine/exposure_test.go

@@ -0,0 +1,142 @@
+package engine
+
+import (
+	"net/netip"
+	"strings"
+	"testing"
+
+	"jarl/internal/model"
+	"jarl/internal/validate"
+)
+
+func problemFor(ps []validate.Problem, code, view string) *validate.Problem {
+	for i, p := range ps {
+		if p.Code == code && (view == "" || p.View == view) {
+			return &ps[i]
+		}
+	}
+	return nil
+}
+
+func TestExposure(t *testing.T) {
+	env := newEnv(t)
+	setupZone(env)
+	env.submit(env.admin,
+		// An internal network with a global IPv6 prefix is still yours.
+		NewRequest(OpACLCreate, 0, ACLInput{Name: model.Ptr("internal-clients"), Elements: &[]string{"2a02:8013:7f3d:10::/64", "192.168.1.0/24"}}),
+		optionReq("allow-transfer", "{ 192.0.2.53; }"),
+	)
+	env.submit(env.admin,
+		NewRequest(OpViewCreate, 0, ViewInput{Name: model.Ptr("internal"), MatchClients: &[]string{"internal-clients", "localhost"}, AdoptZones: true}),
+		NewRequest(OpViewCreate, 0, ViewInput{Name: model.Ptr("external"), MatchClients: &[]string{"!internal-clients", "any"}}),
+		NewRequest(OpViewCreate, 0, ViewInput{Name: model.Ptr("dmz"), MatchClients: &[]string{"any"}, MatchDestinations: &[]string{"10.9.0.53"}}),
+	)
+	st := env.state()
+	exps := map[string]validate.Exposure{}
+	for _, x := range env.e.Exposures(st) {
+		exps[x.View] = x
+	}
+	if x := exps["internal"]; x.Public || !strings.Contains(x.Reason, "no catch-all") {
+		t.Errorf("internal = %+v", x)
+	}
+	if x := exps["external"]; !x.Public || x.Reason != "match-clients ends in any" {
+		t.Errorf("external = %+v", x)
+	}
+	if x := exps["dmz"]; x.Public || !strings.Contains(x.Reason, "match-destinations") {
+		t.Errorf("dmz = %+v", x)
+	}
+
+	ps := env.e.validate(st)
+	for _, code := range []string{"exposure_rate_limit", "exposure_minimal_any"} {
+		if problemFor(ps, code, "external") == nil {
+			t.Errorf("no %s for external", code)
+		}
+		if problemFor(ps, code, "internal") != nil || problemFor(ps, code, "dmz") != nil {
+			t.Errorf("%s for a private view", code)
+		}
+	}
+	for _, code := range []string{"exposure_version", "exposure_hostname"} {
+		if problemFor(ps, code, "") == nil {
+			t.Errorf("no %s", code)
+		}
+	}
+
+	// The rate limit fix starts in log-only mode and exempts the
+	// secondaries.
+	ext := st.ViewByName("external")
+	reqs, desc := ExposureFix(st, ext.ID, "exposure_rate_limit")
+	if len(reqs) != 1 || !strings.Contains(desc, "{ responses-per-second 10; log-only yes; exempt-clients { 192.0.2.53; }; }") {
+		t.Fatalf("fix = %v %q", reqs, desc)
+	}
+	env.submit(env.admin, reqs...)
+	ps = env.e.validate(env.state())
+	if problemFor(ps, "exposure_rate_limit", "external") != nil {
+		t.Error("rate limit warning stays after the fix")
+	}
+	if p := problemFor(ps, "exposure_rate_limit_log_only", "external"); p == nil || p.Severity != validate.Info {
+		t.Errorf("log-only = %+v", p)
+	}
+	reqs, desc = ExposureFix(env.state(), ext.ID, "exposure_rate_limit_log_only")
+	if !strings.Contains(desc, "{ responses-per-second 10; exempt-clients { 192.0.2.53; }; }") {
+		t.Errorf("enforce = %q", desc)
+	}
+	env.submit(env.admin, reqs...)
+	if p := problemFor(env.e.validate(env.state()), "exposure_rate_limit_log_only", "external"); p != nil {
+		t.Errorf("still log-only: %+v", p)
+	}
+
+	// Opening the server up needs confirming.
+	open := optionReqView("allow-recursion", "{ any; }", ext.ID)
+	if e := env.submitErr(env.admin, open); e.Kind != KindRisk || !strings.Contains(e.Message, "open resolver") {
+		t.Fatalf("open resolver without confirming: %+v", e)
+	}
+	if _, err := env.e.Submit(env.ctx, []Request{open}, env.admin, "test", "", ApplyOptions{AcceptRisk: true}); err != nil {
+		t.Fatalf("with accept risk: %v", err)
+	}
+	// Acknowledged, it stays as info, with who and why.
+	env.submit(env.admin, NewRequest(OpExposureAck, 0, AckInput{View: "external", Code: "security_open_resolver", Reason: "public resolver for the club"}))
+	p := problemFor(env.e.validate(env.state()), "security_open_resolver", "external")
+	if p == nil || p.Severity != validate.Info || p.Acknowledged == nil || !strings.Contains(p.Message, "acknowledged by admin on 7 Oct 2026: public resolver for the club") {
+		t.Errorf("acknowledged = %+v", p)
+	}
+	if e := env.submitErr(env.admin, NewRequest(OpExposureAck, 0, AckInput{View: "external", Code: "security_open_resolver"})); e.Kind != KindBadRequest {
+		t.Errorf("ack without a reason: %+v", e)
+	}
+	// Reverting the acknowledgement brings the warning back.
+	env.submit(env.admin, NewRequest(OpExposureUnack, 0, AckInput{View: "external", Code: "security_open_resolver"}))
+	if p := problemFor(env.e.validate(env.state()), "security_open_resolver", "external"); p == nil || p.Severity != validate.Warning {
+		t.Errorf("after unack = %+v", p)
+	}
+	// Marking a view private takes it out of the checks.
+	env.submit(env.admin, NewRequest(OpViewUpdate, ext.ID, ViewInput{Exposure: model.Ptr("private")}))
+	if p := problemFor(env.e.validate(env.state()), "security_open_resolver", "external"); p != nil {
+		t.Errorf("private view still checked: %+v", p)
+	}
+	if e := env.submitErr(env.admin, NewRequest(OpViewUpdate, ext.ID, ViewInput{Exposure: model.Ptr("internet")})); e.Kind != KindBadRequest {
+		t.Errorf("bad exposure: %+v", e)
+	}
+}
+
+// A server without views is public only when named listens on an
+// address that isn't private.
+func TestServerExposure(t *testing.T) {
+	env := newEnv(t)
+	setupZone(env)
+	if x := env.e.Exposures(env.state())[0]; x.Public {
+		t.Errorf("no addresses known = %+v", x)
+	}
+	env.e.cfg.LocalAddrs = func() []netip.Addr {
+		return []netip.Addr{netip.MustParseAddr("192.168.1.2"), netip.MustParseAddr("2a02:8013:7f3d:10::53")}
+	}
+	if x := env.e.Exposures(env.state())[0]; !x.Public || !strings.Contains(x.Reason, "2a02:8013:7f3d:10::53") {
+		t.Errorf("GUA address = %+v", x)
+	}
+	env.submit(env.admin, NewRequest(OpSettingsUpdate, 0, SettingsInput{Exposure: model.Ptr("private")}))
+	if x := env.e.Exposures(env.state())[0]; x.Public || x.Override != "private" {
+		t.Errorf("marked private = %+v", x)
+	}
+}
+
+func optionReqView(name, value string, viewID int64) Request {
+	return NewRequest(OpOptionCreate, 0, OptionInput{Scope: model.Ptr(model.ScopeView), ScopeID: &viewID, Name: &name, Value: &value})
+}

internal/engine/inputs.go

@@ -51,8 +51,21 @@ const (
 	// operations.
 	OpRecordDisable = "record.disable"
 	OpRecordEnable  = "record.enable"
+	// Acknowledging an exposure finding (docs/exposure.md), and taking it
+	// back, become view.update or settings.update operations.
+	OpExposureAck   = "exposure.ack"
+	OpExposureUnack = "exposure.unack"
 )
 
+// AckInput acknowledges (or un-acknowledges) an exposure finding of a view
+// (by ID or name), or of the server (neither given).
+type AckInput struct {
+	ViewID int64  `json:"view_id,omitempty"`
+	View   string `json:"view,omitempty"`
+	Code   string `json:"code"`
+	Reason string `json:"reason,omitempty"`
+}
+
 // OpKinds lists all operation kinds.
 var OpKinds = []string{OpZoneCreate, OpZoneUpdate, OpZoneDelete, OpRecordCreate, OpRecordUpdate, OpRecordDelete, OpRRSetReplace,
 	OpViewCreate, OpViewUpdate, OpViewDelete, OpViewReorder, OpACLCreate, OpACLUpdate, OpACLDelete,
@@ -184,6 +197,9 @@ type ViewInput struct {
 	AdoptZones bool `json:"adopt_zones,omitempty"`
 	// Cascade (delete) also deletes the view's zones.
 	Cascade bool `json:"cascade,omitempty"`
+	// Exposure is "auto" (or ""), "public" or "private" (docs/exposure.md).
+	Exposure     *string                  `json:"exposure,omitempty"`
+	Acknowledged *[]model.Acknowledgement `json:"acknowledged,omitempty"`
 }
 
 // ReorderInput sets the order of views.
@@ -227,6 +243,9 @@ type SettingsInput struct {
 	Expire       *uint32   `json:"expire,omitempty"`
 	NegativeTTL  *uint32   `json:"negative_ttl,omitempty"`
 	SerialPolicy *string   `json:"serial_policy,omitempty"`
+	// Exposure and Acknowledged are the server's (docs/exposure.md).
+	Exposure     *string                  `json:"exposure,omitempty"`
+	Acknowledged *[]model.Acknowledgement `json:"acknowledged,omitempty"`
 }
 
 // DeleteInput carries options for delete operations.

internal/engine/ops.go

@@ -765,9 +765,41 @@ func setViewFields(v *model.View, in *ViewInput) error {
 	if in.Position != nil {
 		v.Position = *in.Position
 	}
+	if in.Exposure != nil {
+		e, err := normalizeExposure(*in.Exposure)
+		if err != nil {
+			return err
+		}
+		v.Exposure = e
+	}
+	if in.Acknowledged != nil {
+		v.Acknowledged = cleanAcks(*in.Acknowledged)
+	}
 	return nil
 }
 
+// normalizeExposure checks an exposure override.
+func normalizeExposure(s string) (string, error) {
+	switch e := strings.ToLower(strings.TrimSpace(s)); e {
+	case "", "auto":
+		return model.ExposureAuto, nil
+	case model.ExposurePublic, model.ExposurePrivate:
+		return e, nil
+	}
+	return "", errf(KindBadRequest, "exposure must be auto, public or private, not %q", s)
+}
+
+// cleanAcks drops empty acknowledgements (nil for none).
+func cleanAcks(acks []model.Acknowledgement) []model.Acknowledgement {
+	var out []model.Acknowledgement
+	for _, a := range acks {
+		if a.Code != "" {
+			out = append(out, a)
+		}
+	}
+	return out
+}
+
 func applyViewCreate(st *model.State, op model.Op, c *applyCtx) error {
 	var in ViewInput
 	if err := decode(op.Data, &in); err != nil {
@@ -1329,6 +1361,16 @@ func applySettings(st *model.State, op model.Op, c *applyCtx) error {
 	if in.SerialPolicy != nil {
 		s.SerialPolicy = strings.ToLower(*in.SerialPolicy)
 	}
+	if in.Exposure != nil {
+		e, err := normalizeExposure(*in.Exposure)
+		if err != nil {
+			return err
+		}
+		s.Exposure = e
+	}
+	if in.Acknowledged != nil {
+		s.Acknowledged = cleanAcks(*in.Acknowledged)
+	}
 	s.Version++
 	return nil
 }