diff --git a/CHANGELOG.md b/CHANGELOG.md
index f3092a3..4c9983f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,14 @@ All notable changes to Housecarl are documented here. The format follows
 
 ### Added
 
+- **Names beside inside addresses.** Connections, the log, quota usage,
+  the dashboard's quotas and the statistics' devices and blocked
+  sources show each inside address's name, found by a reverse lookup:
+  `laptop 192.168.1.20` in the web UI, `192.168.1.20 (laptop)` in `hc`.
+  Only inside addresses are looked up (an inside zone's networks, and
+  private ones outside the external zones'). Names are cached for 10
+  minutes and never stored. `names.enabled`, `names.resolver` and
+  `names.cache` in housecarl.yaml; `hc --no-names`; `POST /names`.
 - **Quotas on the dashboard.** With any rule holding a quota, the
   dashboard lists them all: the allowance, what is used (for a
   per-address quota, how many addresses and the busiest) with a bar, and
@@ -62,6 +70,8 @@ All notable changes to Housecarl are documented here. The format follows
 
 ### Fixed
 
+- `hc stats top devices` listed each device twice (once for what it
+  received, once for what it sent); it is one row with both again.
 - `hc rule add --before/--after/--first` made two changes (create at the
   end, then move), so two history entries, two probations, and the rule
   briefly in force at the end of its chain; staged in a changeset, the
diff --git a/cmd/hc/firewall.go b/cmd/hc/firewall.go
index 839940b..031ee83 100644
--- a/cmd/hc/firewall.go
+++ b/cmd/hc/firewall.go
@@ -298,6 +298,13 @@ func quotasCmd() *cobra.Command {
 			if err != nil {
 				return err
 			}
+			var addrs []string
+			for _, q := range qs {
+				for _, a := range q.Addresses {
+					addrs = append(addrs, a.Address)
+				}
+			}
+			names := lookupNames(addrs...)
 			return output(qs, func(w io.Writer) {
 				fmt.Fprintln(w, "RULE\tUSED\tOF\tRESETS\tNEXT RESET")
 				for _, q := range qs {
@@ -317,7 +324,7 @@ func quotasCmd() *cobra.Command {
 					}
 					fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\n", q.Rule, humanBytes(q.Used), of, resets, next)
 					for _, a := range q.Addresses {
-						fmt.Fprintf(w, "  %s\t%s\t\t\t\n", a.Address, humanBytes(a.Used))
+						fmt.Fprintf(w, "  %s\t%s\t\t\t\n", named(names, a.Address, a.Address), humanBytes(a.Used))
 					}
 				}
 			})
@@ -341,6 +348,11 @@ func logCmd() *cobra.Command {
 			var last time.Time
 			print := func(es []api.LogEntry) {
 				sort.Slice(es, func(i, j int) bool { return es[i].Time.Before(es[j].Time) })
+				var addrs []string
+				for _, e := range es {
+					addrs = append(addrs, e.Source, e.Dest)
+				}
+				names := lookupNames(addrs...)
 				for _, e := range es {
 					last = e.Time
 					src, dst := e.Source, e.Dest
@@ -350,6 +362,7 @@ func logCmd() *cobra.Command {
 					if e.DestPort != 0 {
 						dst = joinPort(dst, e.DestPort)
 					}
+					src, dst = named(names, e.Source, src), named(names, e.Dest, dst)
 					what := e.Protocol
 					if e.ICMPType != "" {
 						what += " " + e.ICMPType
diff --git a/cmd/hc/main.go b/cmd/hc/main.go
index 33061cd..23a741f 100644
--- a/cmd/hc/main.go
+++ b/cmd/hc/main.go
@@ -46,6 +46,7 @@ var (
 	flagCACert    string
 	flagQuiet     bool
 	flagNoConfirm bool
+	flagNoNames   bool
 	// lastClient is the client the command made (to confirm a change by
 	// itself after it).
 	lastClient *client.Client
@@ -182,6 +183,7 @@ Exit codes: 0 ok, 1 error, 3 not authenticated or not allowed, 4 not found,
 	pf.StringVar(&flagCACert, "ca-cert", "", "PEM file with a CA to trust for the server's certificate")
 	pf.BoolVarP(&flagQuiet, "quiet", "q", false, "print only errors (and IDs of new objects)")
 	pf.BoolVar(&flagNoConfirm, "no-confirm", false, "leave a change on probation instead of confirming it once this client reaches Housecarl again")
+	pf.BoolVar(&flagNoNames, "no-names", false, "show inside addresses without their names (reverse lookups)")
 	pf.Int64VarP(&flagChangeset, "changeset", "C", 0, "stage configuration changes in this changeset instead of applying them (env HOUSECARL_CHANGESET)")
 	root.AddGroup(&cobra.Group{ID: "fw", Title: "Firewall:"}, &cobra.Group{ID: "changes", Title: "Changes:"}, &cobra.Group{ID: "admin", Title: "Administration:"})
 	add := func(group string, cmds ...*cobra.Command) {
diff --git a/cmd/hc/objects.go b/cmd/hc/objects.go
index 1bd97a4..346f60e 100644
--- a/cmd/hc/objects.go
+++ b/cmd/hc/objects.go
@@ -49,6 +49,46 @@ func counters() map[string]api.Counter {
 	return cs.Counters
 }
 
+// lookupNames asks for inside addresses' names, for tables: none with
+// --no-names, another output format, or when they can't be had.
+func lookupNames(addrs ...string) map[string]string {
+	out := map[string]string{}
+	if flagNoNames || flagOutput != "table" {
+		return out
+	}
+	seen := map[string]bool{}
+	var list []string
+	for _, a := range addrs {
+		if a != "" && !seen[a] {
+			seen[a] = true
+			list = append(list, a)
+		}
+	}
+	if len(list) == 0 {
+		return out
+	}
+	c, err := newClient()
+	if err != nil {
+		return out
+	}
+	var ns api.Names
+	if c.Do(ctx(), "POST", "/names", nil, api.NamesInput{Addresses: list}, &ns) != nil {
+		return out
+	}
+	for a, n := range ns.Names {
+		out[a] = strings.SplitN(n, ".", 2)[0]
+	}
+	return out
+}
+
+// named adds an address's name to text (the address, or address:port).
+func named(names map[string]string, addr, text string) string {
+	if n := names[addr]; n != "" {
+		return text + " (" + n + ")"
+	}
+	return text
+}
+
 func hits(c map[string]api.Counter, marks ...string) string {
 	var p uint64
 	found := false
diff --git a/cmd/hc/stats.go b/cmd/hc/stats.go
index 4a13449..ceddad4 100644
--- a/cmd/hc/stats.go
+++ b/cmd/hc/stats.go
@@ -283,6 +283,7 @@ func statsTopCmd() *cobra.Command {
 				for _, l := range [][]statEntry{down, up} {
 					for _, e := range l {
 						if _, ok := out[e.Key]; !ok {
+							out[e.Key] = [2]int64{}
 							order = append(order, e.Key)
 						}
 					}
@@ -297,10 +298,11 @@ func statsTopCmd() *cobra.Command {
 					v[1] = e.Count
 					out[e.Key] = v
 				}
+				names := lookupNames(order...)
 				return output(map[string]any{"up": up, "down": down}, func(w io.Writer) {
 					fmt.Fprintln(w, "DEVICE\tRECEIVED\tSENT")
 					for _, k := range order {
-						fmt.Fprintf(w, "%s\t%s\t%s\n", k, humanBytes(out[k][0]), humanBytes(out[k][1]))
+						fmt.Fprintf(w, "%s\t%s\t%s\n", named(names, k, k), humanBytes(out[k][0]), humanBytes(out[k][1]))
 					}
 				})
 			case "blocked", "tried":
@@ -309,10 +311,14 @@ func statsTopCmd() *cobra.Command {
 				if err != nil {
 					return err
 				}
+				var names map[string]string
+				if args[0] == "blocked" {
+					names = lookupNames(keys(es)...)
+				}
 				return output(es, func(w io.Writer) {
 					fmt.Fprintln(w, map[string]string{"blocked": "SOURCE", "tried": "WHAT"}[args[0]]+"\tPACKETS")
 					for _, e := range es {
-						fmt.Fprintf(w, "%s\t%d\n", e.Key, e.Count)
+						fmt.Fprintf(w, "%s\t%d\n", named(names, e.Key, e.Key), e.Count)
 					}
 				})
 			case "quota":
@@ -323,10 +329,11 @@ func statsTopCmd() *cobra.Command {
 				if err != nil {
 					return err
 				}
+				names := lookupNames(keys(es)...)
 				return output(es, func(w io.Writer) {
 					fmt.Fprintln(w, "ADDRESS\tUSED")
 					for _, e := range es {
-						fmt.Fprintf(w, "%s\t%s\n", e.Key, humanBytes(e.Count))
+						fmt.Fprintf(w, "%s\t%s\n", named(names, e.Key, e.Key), humanBytes(e.Count))
 					}
 				})
 			}
@@ -338,6 +345,15 @@ func statsTopCmd() *cobra.Command {
 	return cmd
 }
 
+// keys are a top list's keys.
+func keys(es []statEntry) []string {
+	var out []string
+	for _, e := range es {
+		out = append(out, e.Key)
+	}
+	return out
+}
+
 func statsRulesCmd() *cobra.Command {
 	var since string
 	var unused bool
diff --git a/cmd/hc/traffic.go b/cmd/hc/traffic.go
index 97f9ddc..d77a74e 100644
--- a/cmd/hc/traffic.go
+++ b/cmd/hc/traffic.go
@@ -38,10 +38,16 @@ rules as it stands.
 			if err != nil {
 				return err
 			}
+			var addrs []string
+			for _, c := range cs {
+				addrs = append(addrs, c.Source, c.Destination)
+			}
+			names := lookupNames(addrs...)
 			return output(cs, func(w io.Writer) {
 				fmt.Fprintln(w, "PROTO\tFROM\tTO\tNAT\tSTATE\tEXPIRES")
 				for _, c := range cs {
-					fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\t%s\n", c.Protocol, hostPort(c.Source, c.SourcePort), hostPort(c.Destination, c.DestinationPort), natText(c), c.State, fmtSeconds(c.Timeout))
+					fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\t%s\n", c.Protocol, named(names, c.Source, hostPort(c.Source, c.SourcePort)),
+						named(names, c.Destination, hostPort(c.Destination, c.DestinationPort)), natText(c), c.State, fmtSeconds(c.Timeout))
 				}
 			})
 		},
diff --git a/cmd/housecarld/main.go b/cmd/housecarld/main.go
index c022327..139503a 100644
--- a/cmd/housecarld/main.go
+++ b/cmd/housecarld/main.go
@@ -32,6 +32,7 @@ import (
 	"housecarl/internal/jarl"
 	"housecarl/internal/linkwatch"
 	"housecarl/internal/model"
+	"housecarl/internal/names"
 	"housecarl/internal/nflog"
 	"housecarl/internal/nft"
 	"housecarl/internal/render"
@@ -176,11 +177,15 @@ func serveCmd() *cobra.Command {
 				acme = certs.New(ctx, certs.Config{ACME: a.cfg.TLS.ACME, Version: version.Short()}, jc, a.store, a.log)
 				go acme.Run(ctx)
 			}
+			var resolver *names.Resolver
+			if a.cfg.Names.Enabled {
+				resolver = names.New(a.cfg.Names.Resolver, time.Duration(a.cfg.Names.Cache))
+			}
 			srv := server.New(server.Config{
 				Listen: a.cfg.Listen, TLSCertFile: a.cfg.TLS.CertFile, TLSKeyFile: a.cfg.TLS.KeyFile, TrustedProxies: a.cfg.Proxies(),
 				SessionLifetime: time.Duration(a.cfg.Session.Lifetime), SessionIdle: time.Duration(a.cfg.Session.IdleTimeout),
 				CookieSecure: a.cfg.Session.CookieSecure, Socket: a.cfg.Socket, ACME: acme,
-				Shadow: a.cfg.Shadow.Enabled, ShadowPosition: a.cfg.Shadow.Position,
+				Shadow: a.cfg.Shadow.Enabled, ShadowPosition: a.cfg.Shadow.Position, Names: resolver,
 			}, eng, fw, host, a.log, web.FS())
 			// Put the ruleset in force: what was on probation when
 			// housecarld stopped is rolled back first. An empty
diff --git a/docs/api.md b/docs/api.md
index 9e2490a..dcbb8ca 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -82,6 +82,7 @@ Creating answers 201, other changes 200.
 | `GET /counters` | `{"since", "counters": {"r12": {"packets", "bytes"}, ...}}`, by mark ([design.md](design.md#its-own-table-only)); totals since housecarld started |
 | `GET /quotas` | each rule's quota: `rule_id`, `rule`, `quota`, `used` (bytes), `addresses` (`[{"address", "used"}]` for a per-address quota), `last_reset`, `next_reset` |
 | `GET /connections[?q=&limit=]` | tracked connections: `family`, `protocol`, `source`, `source_port`, `destination`, `destination_port` (or `icmp_id`, `icmp_type`, `icmp_code`), `dnat_to`, `dnat_port`, `snat_to`, `state`, `assured`, `timeout` (seconds left), `packets` and `bytes` when the kernel counts them. `q`: all of its words in the addresses, `:port`, protocol, state |
+| `POST /names` | `{"addresses": [...]}` (at most 2000): `{"enabled", "names": {"192.168.1.20": "laptop.example.net"}}`, the names of the inside addresses among them, by reverse lookup ([configuration.md](configuration.md#names)). Addresses without a name, outside ones, and those still being looked up after a second are left out; ask again for those. `log:read` |
 | `POST /connections/close` | `{"connections": [...]}` (as listed) or `{"search": "192.168.1.50"}`: delete their tracking entries (`config:write`, audited); answers `{"closed": N}`. 409 in shadow mode |
 | `POST /trace` | `{"address", "port", "protocol", "seconds"}` (5-600, default 60): start tracing (`config:write`, audited); 409 while one runs |
 | `GET /trace` | the trace running, or the last: `running`, `input`, `started`, `ends`, `error`, `packets`: each with `time`, `in`, `out`, `protocol`, addresses and ports, `tcp_flags`, `icmp_type`, `steps` (`table`, `chain`, `kind` rule or policy, `rule`, `mark`, `label`, `verdict`), `verdict` (accepted, dropped) and `decided_by`; in shadow mode `would_drop`, the step where Housecarl would have dropped it |
diff --git a/docs/cli.md b/docs/cli.md
index 9c4850c..ed24790 100644
--- a/docs/cli.md
+++ b/docs/cli.md
@@ -32,6 +32,7 @@ command and its flags.
 | `-C, --changeset ID` | `HOUSECARL_CHANGESET` (checked, see [Changesets](#changesets)) | stage configuration changes in this changeset instead of making them |
 | `-o, --output FORMAT` | | `table` (default), `json`, `yaml` or `id` |
 | `-q, --quiet` | | print only errors (and the IDs of new objects) |
+| `--no-names` | | show inside addresses without their names: tables show `192.168.1.20 (laptop)` ([configuration.md](configuration.md#names)) |
 
 Exit codes: 0 ok, 1 error, 3 not authenticated or not allowed, 4 not
 found, 5 conflict, 6 invalid or refused by validation or nftables, 7
diff --git a/docs/configuration.md b/docs/configuration.md
index 142b58d..b75dfec 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -32,12 +32,34 @@ reads the file when it starts.
 | `stats.top_n` | `100` | entries kept per top list, per hour and per day |
 | `shadow.enabled` | `false` | shadow mode: Housecarl's ruleset is loaded beside the firewall you have, but blocks, rejects and translates nothing; its counters, log and tracer show what it would do. No change is on probation, and takeovers and closing connections are refused ([shadow.md](shadow.md)) |
 | `shadow.position` | `after` | where Housecarl's filter chains run in shadow mode: `after` the other firewall's (`filter + 10`: it sees only what that one lets through, so what it would drop is what switching would break) or `before` them (`filter - 10`: it sees every packet) |
+| `names.enabled` | `true` | show inside addresses' names beside them, found by reverse lookups (below) |
+| `names.resolver` | `""` | the DNS server to ask, such as `10.10.0.1:53`; empty: the system's (`/etc/hosts`, then `/etc/resolv.conf`) |
+| `names.cache` | `10m` | how long a name, or the lack of one, is kept |
 
 Durations are written `15s`, `12h` or `30d`.
 
 Shadow mode is here, and not a firewall setting, so that no user or API
 token can switch enforcement off; restart housecarld to switch.
 
+### Names
+
+The web UI and `hc` show a name beside each **inside** address in
+connections, the log, quotas and traffic per device: `laptop
+192.168.1.20`. Housecarl finds it with a reverse (PTR) lookup, so the
+names are your reverse zones' (and `/etc/hosts`'). An address counts as
+inside when it is in a network connected to an inside zone's interface,
+or private (`10.0.0.0/8`, `172.16.0.0/12`, `192.168.0.0/16`, `fc00::/7`)
+and not in an external zone's network. Outside addresses get no name:
+their reverse zones belong to whoever holds the addresses, who would
+choose the names, and looking up every scanner is slow.
+
+Names are looked up when a page or `hc` asks, cached (a failed lookup is
+tried again after a minute), and never stored: statistics stay by
+address. With a split DNS (views), the server asked must answer the
+firewall as an inside client; set `names.resolver` if the system's
+resolver doesn't. IPv6 traffic per device is counted per /64, which has
+no name. `hc --no-names` leaves them out.
+
 The probation's length is a firewall setting, not here: `hc settings set
 --probation 5m`. So is counting traffic per device for the statistics:
 `hc settings set --stats-per-device on`.
diff --git a/internal/api/types.go b/internal/api/types.go
index 8caefb5..2238b26 100644
--- a/internal/api/types.go
+++ b/internal/api/types.go
@@ -384,6 +384,19 @@ type Connection struct {
 	Bytes   uint64 `json:"bytes,omitempty"`
 }
 
+// NamesInput asks for the names of addresses (POST /names).
+type NamesInput struct {
+	Addresses []string `json:"addresses"`
+}
+
+// Names are the names found for the inside addresses asked about, by
+// address; those without one (or still being looked up) are left out.
+// Enabled is false when names are off (names.enabled).
+type Names struct {
+	Enabled bool              `json:"enabled"`
+	Names   map[string]string `json:"names"`
+}
+
 // CloseConnections closes connections: these, or every one Search finds
 // (as GET /connections?q= does).
 type CloseConnections struct {
diff --git a/internal/config/config.go b/internal/config/config.go
index 9e5927f..dde117f 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -44,6 +44,19 @@ type Config struct {
 	// Shadow loads the ruleset without letting it block, reject or
 	// translate anything, beside the firewall in force (docs/shadow.md).
 	Shadow Shadow `yaml:"shadow"`
+	// Names shows inside addresses' names, by reverse lookups
+	// (docs/configuration.md).
+	Names Names `yaml:"names"`
+}
+
+// Names configures the reverse lookups that put names beside inside
+// addresses in the web UI and hc.
+type Names struct {
+	Enabled bool `yaml:"enabled"`
+	// Resolver is a DNS server ("10.10.0.1:53"; "": the system's).
+	Resolver string `yaml:"resolver"`
+	// Cache is how long a name is kept.
+	Cache Duration `yaml:"cache"`
 }
 
 // Shadow is shadow mode: Housecarl's ruleset is loaded and counts, logs
@@ -224,6 +237,7 @@ func Default() *Config {
 		Stats: Stats{Enabled: true, Database: "/var/lib/housecarl/stats.db", TopN: 100,
 			Retention: StatsRetention{Minute: Duration(7 * 24 * time.Hour), Hour: Duration(90 * 24 * time.Hour), Day: Duration(730 * 24 * time.Hour)}},
 		Shadow: Shadow{Position: ShadowAfter},
+		Names:  Names{Enabled: true, Cache: Duration(10 * time.Minute)},
 		TLS:    TLS{ACME: ACME{Directory: "letsencrypt-staging", Resolvers: []string{"1.1.1.1:53", "9.9.9.9:53", "8.8.8.8:53"}, CheckPropagation: true}},
 	}
 }
@@ -298,6 +312,14 @@ func (c *Config) check() error {
 	if c.Shadow.Position != ShadowAfter && c.Shadow.Position != ShadowBefore {
 		return fmt.Errorf("shadow.position must be after or before")
 	}
+	if c.Names.Resolver != "" {
+		if _, err := netip.ParseAddrPort(c.Names.Resolver); err != nil {
+			return fmt.Errorf("names.resolver must be an address and port, such as 10.10.0.1:53")
+		}
+	}
+	if c.Names.Cache <= 0 {
+		return fmt.Errorf("names.cache must be a duration, such as 10m")
+	}
 	return nil
 }
 
diff --git a/internal/names/names.go b/internal/names/names.go
new file mode 100644
index 0000000..15b933f
--- /dev/null
+++ b/internal/names/names.go
@@ -0,0 +1,152 @@
+// Package names finds the names of addresses by reverse lookups, for
+// showing them beside the addresses (connections, the log, quotas,
+// traffic per device). Names are cached and never stored: statistics stay
+// keyed by address.
+package names
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/netip"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Lookups running at once, and the most names kept.
+const (
+	parallel = 16
+	maxCache = 20000
+)
+
+// Resolver looks up and caches addresses' names.
+type Resolver struct {
+	lookup func(ctx context.Context, addr string) ([]string, error)
+	// ttl is how long a name (or its absence) is kept; a lookup that
+	// failed (a timeout, a server error) is tried again after retry.
+	ttl, retry time.Duration
+	timeout    time.Duration
+	now        func() time.Time
+
+	mu      sync.Mutex
+	cache   map[netip.Addr]entry
+	pending map[netip.Addr]chan struct{}
+	sem     chan struct{}
+}
+
+type entry struct {
+	name    string
+	expires time.Time
+}
+
+// New makes a resolver asking server ("10.10.0.1:53"; "" for the
+// system's, /etc/hosts then /etc/resolv.conf), keeping names for ttl.
+func New(server string, ttl time.Duration) *Resolver {
+	res := &net.Resolver{PreferGo: true}
+	if server != "" {
+		res.Dial = func(ctx context.Context, network, _ string) (net.Conn, error) {
+			var d net.Dialer
+			return d.DialContext(ctx, network, server)
+		}
+	}
+	return NewFunc(res.LookupAddr, ttl)
+}
+
+// NewFunc makes a resolver with its own lookup (tests).
+func NewFunc(lookup func(ctx context.Context, addr string) ([]string, error), ttl time.Duration) *Resolver {
+	return &Resolver{lookup: lookup, ttl: ttl, retry: time.Minute, timeout: 2 * time.Second, now: time.Now,
+		cache: map[netip.Addr]entry{}, pending: map[netip.Addr]chan struct{}{}, sem: make(chan struct{}, parallel)}
+}
+
+// Names returns the names of addrs: those cached, and those looked up
+// within wait. Lookups still running then carry on and are cached for
+// the next call. An address without a name is left out.
+func (r *Resolver) Names(ctx context.Context, addrs []netip.Addr, wait time.Duration) map[netip.Addr]string {
+	out := map[netip.Addr]string{}
+	var waiting []netip.Addr
+	var done []chan struct{}
+	now := r.now()
+	r.mu.Lock()
+	for _, a := range addrs {
+		if e, ok := r.cache[a]; ok && now.Before(e.expires) {
+			if e.name != "" {
+				out[a] = e.name
+			}
+			continue
+		}
+		ch, ok := r.pending[a]
+		if !ok {
+			ch = make(chan struct{})
+			r.pending[a] = ch
+			go r.resolve(a, ch)
+		}
+		waiting = append(waiting, a)
+		done = append(done, ch)
+	}
+	r.mu.Unlock()
+	if len(waiting) == 0 {
+		return out
+	}
+	t := time.NewTimer(wait)
+	defer t.Stop()
+	for _, ch := range done {
+		select {
+		case <-ch:
+		case <-t.C:
+			return r.collect(out, waiting)
+		case <-ctx.Done():
+			return r.collect(out, waiting)
+		}
+	}
+	return r.collect(out, waiting)
+}
+
+// collect adds what the lookups found for addrs.
+func (r *Resolver) collect(out map[netip.Addr]string, addrs []netip.Addr) map[netip.Addr]string {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	for _, a := range addrs {
+		if e, ok := r.cache[a]; ok && e.name != "" {
+			out[a] = e.name
+		}
+	}
+	return out
+}
+
+func (r *Resolver) resolve(a netip.Addr, done chan struct{}) {
+	r.sem <- struct{}{}
+	ctx, cancel := context.WithTimeout(context.Background(), r.timeout)
+	ns, err := r.lookup(ctx, a.String())
+	cancel()
+	<-r.sem
+	e := entry{expires: r.now().Add(r.ttl)}
+	var dnsErr *net.DNSError
+	switch {
+	case err == nil && len(ns) > 0:
+		e.name = strings.TrimSuffix(ns[0], ".")
+	case err != nil && !(errors.As(err, &dnsErr) && dnsErr.IsNotFound):
+		e.expires = r.now().Add(r.retry)
+	}
+	r.mu.Lock()
+	if len(r.cache) >= maxCache {
+		r.prune()
+	}
+	r.cache[a] = e
+	delete(r.pending, a)
+	r.mu.Unlock()
+	close(done)
+}
+
+// prune drops expired names, or all of them when none has expired.
+func (r *Resolver) prune() {
+	now := r.now()
+	for a, e := range r.cache {
+		if !now.Before(e.expires) {
+			delete(r.cache, a)
+		}
+	}
+	if len(r.cache) >= maxCache {
+		clear(r.cache)
+	}
+}
diff --git a/internal/names/names_test.go b/internal/names/names_test.go
new file mode 100644
index 0000000..2434248
--- /dev/null
+++ b/internal/names/names_test.go
@@ -0,0 +1,57 @@
+package names
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/netip"
+	"sync/atomic"
+	"testing"
+	"time"
+)
+
+func TestNames(t *testing.T) {
+	var calls atomic.Int32
+	slow := make(chan struct{})
+	r := NewFunc(func(ctx context.Context, addr string) ([]string, error) {
+		calls.Add(1)
+		switch addr {
+		case "10.0.0.1":
+			return []string{"nas.example.net."}, nil
+		case "10.0.0.2":
+			return nil, &net.DNSError{Err: "no such host", Name: addr, IsNotFound: true}
+		case "10.0.0.3":
+			return nil, errors.New("server failure")
+		case "10.0.0.4":
+			<-slow
+			return []string{"slow.example.net."}, nil
+		}
+		return nil, nil
+	}, time.Hour)
+	a := netip.MustParseAddr
+	all := []netip.Addr{a("10.0.0.1"), a("10.0.0.2"), a("10.0.0.3"), a("10.0.0.4")}
+
+	got := r.Names(context.Background(), all, 200*time.Millisecond)
+	if len(got) != 1 || got[a("10.0.0.1")] != "nas.example.net" {
+		t.Fatalf("first call: %v", got)
+	}
+	// The slow lookup finishes later and is there next time; the others
+	// come from the cache, the failure too until it is retried.
+	close(slow)
+	time.Sleep(50 * time.Millisecond)
+	got = r.Names(context.Background(), all, 200*time.Millisecond)
+	if len(got) != 2 || got[a("10.0.0.4")] != "slow.example.net" {
+		t.Fatalf("second call: %v", got)
+	}
+	if n := calls.Load(); n != 4 {
+		t.Fatalf("%d lookups, want 4 (cached)", n)
+	}
+
+	// A failure is tried again after retry, a missing name after ttl.
+	now := time.Now().Add(2 * time.Minute)
+	r.now = func() time.Time { return now }
+	r.Names(context.Background(), all, 200*time.Millisecond)
+	if n := calls.Load(); n != 5 {
+		t.Fatalf("%d lookups, want 5 (the failure again)", n)
+	}
+}
diff --git a/internal/server/h_traffic.go b/internal/server/h_traffic.go
index 23bb24d..d9688a5 100644
--- a/internal/server/h_traffic.go
+++ b/internal/server/h_traffic.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net/http"
+	"net/netip"
 	"sort"
 	"strconv"
 	"strings"
@@ -88,6 +89,83 @@ func (s *Server) listConnections(w http.ResponseWriter, r *http.Request, p *auth
 	return nil
 }
 
+// lookupNames finds the names of the inside addresses asked about
+// (docs/configuration.md#names), waiting at most a second for lookups.
+func (s *Server) lookupNames(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
+	if err := require(p, auth.ResLog, false); err != nil {
+		return err
+	}
+	var in api.NamesInput
+	if err := decodeJSON(r, &in); err != nil {
+		return err
+	}
+	if len(in.Addresses) > maxNames {
+		return badRequest("ask for at most %d addresses at once", maxNames)
+	}
+	out := api.Names{Enabled: s.cfg.Names != nil, Names: map[string]string{}}
+	if s.cfg.Names == nil {
+		writeJSON(w, http.StatusOK, out)
+		return nil
+	}
+	inside := s.insideNetworks(s.eng.State())
+	asked := map[netip.Addr][]string{}
+	var addrs []netip.Addr
+	for _, a := range in.Addresses {
+		ad, err := netip.ParseAddr(a)
+		if err != nil || !inside(ad.Unmap()) {
+			continue
+		}
+		ad = ad.Unmap()
+		if _, ok := asked[ad]; !ok {
+			addrs = append(addrs, ad)
+		}
+		asked[ad] = append(asked[ad], a)
+	}
+	for a, n := range s.cfg.Names.Names(r.Context(), addrs, time.Second) {
+		for _, as := range asked[a] {
+			out.Names[as] = n
+		}
+	}
+	writeJSON(w, http.StatusOK, out)
+	return nil
+}
+
+// maxNames is the most addresses one POST /names may ask about.
+const maxNames = 2000
+
+// insideNetworks tells inside addresses: in a network connected to an
+// inside zone's interface, or private and not in an external zone's.
+func (s *Server) insideNetworks(st *model.State) func(netip.Addr) bool {
+	external := map[string]bool{}
+	for _, z := range st.Zones {
+		external[z.Name] = z.External
+	}
+	var in, out []netip.Prefix
+	for p, zone := range s.connected(st) {
+		if external[zone] {
+			out = append(out, p)
+		} else {
+			in = append(in, p)
+		}
+	}
+	return func(a netip.Addr) bool {
+		if a.IsLoopback() || a.IsUnspecified() || a.IsMulticast() || a.IsLinkLocalUnicast() {
+			return false
+		}
+		for _, p := range in {
+			if p.Contains(a) {
+				return true
+			}
+		}
+		for _, p := range out {
+			if p.Contains(a) {
+				return false
+			}
+		}
+		return a.IsPrivate()
+	}
+}
+
 // closeConnections deletes tracking entries: the rules check those
 // connections again with their next packet.
 func (s *Server) closeConnections(w http.ResponseWriter, r *http.Request, p *auth.Principal) error {
diff --git a/internal/server/routes.go b/internal/server/routes.go
index ce3ccb3..fac52a5 100644
--- a/internal/server/routes.go
+++ b/internal/server/routes.go
@@ -41,6 +41,7 @@ func (s *Server) routes() {
 	m.HandleFunc("GET "+p+"/quotas", s.authed(s.listQuotas))
 	m.HandleFunc("GET "+p+"/connections", s.authed(s.listConnections))
 	m.HandleFunc("POST "+p+"/connections/close", s.authed(s.closeConnections))
+	m.HandleFunc("POST "+p+"/names", s.authed(s.lookupNames))
 	m.HandleFunc("GET "+p+"/trace", s.authed(s.getTrace))
 	m.HandleFunc("POST "+p+"/trace", s.authed(s.startTrace))
 	m.HandleFunc("DELETE "+p+"/trace", s.authed(s.stopTrace))
diff --git a/internal/server/server.go b/internal/server/server.go
index 26280f1..0da4c84 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -23,6 +23,7 @@ import (
 	"housecarl/internal/certs"
 	"housecarl/internal/engine"
 	"housecarl/internal/model"
+	"housecarl/internal/names"
 	"housecarl/internal/nft"
 	"housecarl/internal/render"
 	"housecarl/internal/stats"
@@ -51,6 +52,8 @@ type Config struct {
 	// after or before, for the status.
 	Shadow         bool
 	ShadowPosition string
+	// Names looks up inside addresses' names (nil: names are off).
+	Names *names.Resolver
 }
 
 // Interfaces lists the host's interfaces with their addresses, and
diff --git a/internal/server/server_test.go b/internal/server/server_test.go
index eda5033..3102592 100644
--- a/internal/server/server_test.go
+++ b/internal/server/server_test.go
@@ -12,6 +12,7 @@ import (
 	"net/http/httptest"
 	"net/netip"
 	"os"
+	"reflect"
 	"strings"
 	"sync"
 	"testing"
@@ -21,6 +22,7 @@ import (
 	"housecarl/internal/auth"
 	"housecarl/internal/engine"
 	"housecarl/internal/model"
+	"housecarl/internal/names"
 	"housecarl/internal/nft"
 	"housecarl/internal/render"
 	"housecarl/internal/stats"
@@ -982,6 +984,41 @@ func TestConnections(t *testing.T) {
 	}
 }
 
+// TestNames: names only for inside addresses (an inside zone's network,
+// or private outside the external zones'), under the address as asked.
+func TestNames(t *testing.T) {
+	var asked []string
+	var mu sync.Mutex
+	e := newEnvWith(t, Config{Names: names.NewFunc(func(_ context.Context, a string) ([]string, error) {
+		mu.Lock()
+		asked = append(asked, a)
+		mu.Unlock()
+		return []string{"host-" + strings.ReplaceAll(a, ".", "-") + ".example.net."}, nil
+	}, time.Hour)})
+	e.call(e.token, "POST", "/zones", model.Zone{Name: "wan", Interfaces: []string{"wan"}, External: true}, nil)
+	e.call(e.token, "POST", "/zones", model.Zone{Name: "lan", Interfaces: []string{"eth1"}}, nil)
+	var out api.Names
+	e.call(e.token, "POST", "/names", api.NamesInput{Addresses: []string{"10.0.10.5", "::ffff:10.0.10.5", "192.168.7.7", "217.155.8.194", "8.8.8.8", "fe80::1", "nonsense"}}, &out)
+	want := map[string]string{"10.0.10.5": "host-10-0-10-5.example.net", "::ffff:10.0.10.5": "host-10-0-10-5.example.net", "192.168.7.7": "host-192-168-7-7.example.net"}
+	if !out.Enabled || !reflect.DeepEqual(out.Names, want) {
+		t.Errorf("names: %+v", out)
+	}
+	if len(asked) != 2 {
+		t.Errorf("looked up %v, want the two inside addresses once each", asked)
+	}
+	var tok api.Token
+	e.call(e.token, "POST", "/me/tokens", api.TokenInput{Name: "monitor", Role: "log"}, &tok)
+	var one, none api.Names
+	if code := e.call(tok.Secret, "POST", "/names", api.NamesInput{Addresses: []string{"10.0.10.5"}}, &one); code != 200 || len(one.Names) != 1 {
+		t.Errorf("with log:read: %d %+v", code, one)
+	}
+	off := newEnv(t)
+	off.call(off.token, "POST", "/names", api.NamesInput{Addresses: []string{"10.0.10.5"}}, &none)
+	if none.Enabled || len(none.Names) != 0 {
+		t.Errorf("names off: %+v", none)
+	}
+}
+
 // TestTrace: a trace runs with the filter's table, collects packets named
 // after Housecarl's objects, and stops when asked; one at a time.
 func TestTrace(t *testing.T) {
diff --git a/internal/web/static/assets/pages/connections.js b/internal/web/static/assets/pages/connections.js
index 01c1998..b50e135 100644
--- a/internal/web/static/assets/pages/connections.js
+++ b/internal/web/static/assets/pages/connections.js
@@ -3,7 +3,7 @@
 import { h, mount, input, debounce, toast, confirmDialog, badge } from "../ui.js";
 import { get, api, can } from "../api.js";
 import { onLeave } from "../app.js";
-import { fmtSeconds } from "../widgets.js";
+import { fmtSeconds, lookupNames, named } from "../widgets.js";
 
 export async function render(el, params, query) {
   const search = input({ type: "search", placeholder: "address, :port, protocol, state…", value: query.get("q") || "" });
@@ -22,14 +22,15 @@ export async function render(el, params, query) {
   };
   const draw = async () => {
     shown = await get("/connections", { q: search.value.trim(), limit: 500 });
+    const names = await lookupNames(shown.flatMap((c) => [c.source, c.destination, c.dnat_to]));
     count.textContent = shown.length === 1 ? "1 connection" : shown.length + " connections";
     mount(out, shown.length ? h("div", { class: "table-wrap" }, h("table", null,
       h("thead", null, h("tr", null, ["Protocol", "From", "To", "NAT", "State", "Expires", ""].map((t) => h("th", null, t)))),
       h("tbody", null, shown.map((c) => h("tr", null,
         h("td", null, c.protocol),
-        h("td", { class: "mono" }, hostPort(c.source, c.source_port)),
-        h("td", { class: "mono" }, hostPort(c.destination, c.destination_port)),
-        h("td", { class: "mono small" }, c.dnat_to ? "to " + hostPort(c.dnat_to, c.dnat_port || c.destination_port) : "", c.snat_to ? (c.dnat_to ? ", " : "") + "as " + c.snat_to : ""),
+        h("td", { class: "mono" }, named(names, c.source, hostPort(c.source, c.source_port))),
+        h("td", { class: "mono" }, named(names, c.destination, hostPort(c.destination, c.destination_port))),
+        h("td", { class: "mono small" }, c.dnat_to ? ["to ", named(names, c.dnat_to, hostPort(c.dnat_to, c.dnat_port || c.destination_port))] : "", c.snat_to ? (c.dnat_to ? ", " : "") + "as " + c.snat_to : ""),
         h("td", null, c.state || "", c.assured ? null : [" ", badge("one way", "")]),
         h("td", { class: "small" }, fmtSeconds(c.timeout)),
         h("td", { class: "actions-cell" }, write ? h("button", { class: "small reveal", onclick: () => close([c], "this connection") }, "Close") : null)))))) :
diff --git a/internal/web/static/assets/pages/dashboard.js b/internal/web/static/assets/pages/dashboard.js
index df2b7c1..3e0cff2 100644
--- a/internal/web/static/assets/pages/dashboard.js
+++ b/internal/web/static/assets/pages/dashboard.js
@@ -3,7 +3,7 @@
 import { h, mount, table, badge, problemsList, time, plural } from "../ui.js";
 import { get, can } from "../api.js";
 import { onLeave } from "../app.js";
-import { describe, hits, humanCount, fmtBytes, usageBar } from "../widgets.js";
+import { describe, hits, humanCount, fmtBytes, usageBar, lookupNames, named } from "../widgets.js";
 import { lineChart, chartCard, legend, timeTable, stepSeconds } from "../charts.js";
 import { bytes } from "./stats.js";
 
@@ -55,7 +55,7 @@ export async function render(el) {
           { label: "Hits", render: (r) => hits(cs, "r" + r.id) },
           { label: "Comment", render: (r) => r.comment },
         ], busiest)) : null,
-      quotas.length ? quotaPanel(quotas) : null,
+      quotas.length ? quotaPanel(quotas, await lookupNames(quotas.map((q) => (q.addresses || [])[0]).filter(Boolean).map((a) => a.address))) : null,
       log.length ? h("div", { class: "panel" },
         h("div", { class: "panel-head" }, h("h2", null, "Latest logged packets"), h("a", { class: "button small", href: "#/log" }, "The log")),
         table([
@@ -73,16 +73,16 @@ export async function render(el) {
 
 // quotaPanel lists every rule's quota with what it used: the total, or
 // for a per-address quota the busiest address (the rest are on the rule).
-function quotaPanel(quotas) {
+function quotaPanel(quotas, names) {
   const perAddress = (q) => q.quota.per_source || q.quota.per_destination;
   const used = (q) => perAddress(q) ? ((q.addresses || [])[0] || { used: 0 }).used : q.used;
   return h("div", { class: "panel" },
     h("div", { class: "panel-head" }, h("h2", null, "Quotas"), h("a", { class: "button small", href: "#/stats" }, "Statistics")),
     table([
-      { label: "Rule", render: (q) => h("a", { href: "#/rules?rule=" + q.rule_id }, "#" + q.rule_id + " ", q.rule) },
+      { label: "Rule", render: (q) => h("a", { href: "#/rules?rule=" + q.rule_id }, q.rule) },
       { label: "Allowance", render: (q) => fmtBytes(q.quota.bytes) + (q.quota.per_source ? " each source" : q.quota.per_destination ? " each destination" : "") },
       { label: "Used", render: (q) => perAddress(q)
-        ? [plural((q.addresses || []).length, "address", "addresses"), q.addresses && q.addresses.length ? ", busiest " + fmtBytes(used(q)) : ""]
+        ? [plural((q.addresses || []).length, "address", "addresses"), q.addresses && q.addresses.length ? [", busiest ", named(names, q.addresses[0].address), " " + fmtBytes(used(q))] : ""]
         : fmtBytes(q.used) },
       { label: "", render: (q) => usageBar(used(q), q.quota.bytes) },
       { label: "Next reset", render: (q) => q.next_reset ? time(q.next_reset) : h("span", { class: "muted" }, "by hand") },
diff --git a/internal/web/static/assets/pages/log.js b/internal/web/static/assets/pages/log.js
index 03ad5fe..b842ee4 100644
--- a/internal/web/static/assets/pages/log.js
+++ b/internal/web/static/assets/pages/log.js
@@ -3,6 +3,7 @@
 import { h, mount, input, debounce, badge } from "../ui.js";
 import { get, state } from "../api.js";
 import { onLeave } from "../app.js";
+import { lookupNames, named } from "../widgets.js";
 
 export async function render(el, params, query) {
   const search = input({ type: "search", placeholder: "address, interface, rule…", value: query.get("q") || "" });
@@ -12,6 +13,7 @@ export async function render(el, params, query) {
   const addr = (a, port) => port ? (a.includes(":") ? "[" + a + "]:" + port : a + ":" + port) : a;
   const draw = async () => {
     const es = await get("/log", { limit: 300, q: search.value.trim() });
+    const names = await lookupNames(es.flatMap((e) => [e.source, e.destination]));
     mount(out, es.length ? h("div", { class: "table-wrap" }, h("table", { class: "activity" },
       h("thead", null, h("tr", null, ["Time", "Why", "In", "Out", "From", "To", "Protocol"].map((t) => h("th", null, t)))),
       h("tbody", null, es.map((e) => h("tr", null,
@@ -19,7 +21,8 @@ export async function render(el, params, query) {
         h("td", null, e.mark && e.mark.startsWith("r") ? h("a", { href: "#/rules?rule=" + e.mark.slice(1), title: "rule #" + e.mark.slice(1) }, e.prefix) : e.prefix,
           e.shadow && /^(drop|reject)$/.test(e.verdict) ? [" ", badge("would " + e.verdict, "warn")] : null),
         h("td", { class: "mono" }, e.in || ""), h("td", { class: "mono" }, e.out || ""),
-        h("td", { class: "mono" }, addr(e.source, e.source_port)), h("td", { class: "mono" }, addr(e.destination, e.destination_port)),
+        h("td", { class: "mono" }, named(names, e.source, addr(e.source, e.source_port))),
+        h("td", { class: "mono" }, named(names, e.destination, addr(e.destination, e.destination_port))),
         h("td", null, e.protocol, e.icmp_type ? " " + e.icmp_type : "", e.tcp_flags ? h("span", { class: "muted small" }, " " + e.tcp_flags) : null)))))) :
       h("div", { class: "empty" }, state.me.mode === "shadow"
         ? "Nothing logged yet. In shadow mode, what the policies would drop is logged; turn logging on for a rule with Edit → Log."
diff --git a/internal/web/static/assets/pages/rules.js b/internal/web/static/assets/pages/rules.js
index 912ad86..4682a88 100644
--- a/internal/web/static/assets/pages/rules.js
+++ b/internal/web/static/assets/pages/rules.js
@@ -2,7 +2,7 @@
 import { h, mount, table, modal, errorBox, field, input, select, checkbox, confirmDialog, badge, textarea, toast } from "../ui.js";
 import { get, api, change, can } from "../api.js";
 import { rerender } from "../app.js";
-import { names, matchEditor, describe, hits, counters, listEditor, rowClass, live, fmtBytes, quotas, usageBar } from "../widgets.js";
+import { names, matchEditor, describe, hits, counters, listEditor, rowClass, live, fmtBytes, quotas, usageBar, lookupNames, named } from "../widgets.js";
 
 const chains = [
   ["input", "Input", "Traffic to the firewall itself."],
@@ -179,10 +179,11 @@ function quotaLine(r, q) {
 }
 
 async function usageDialog(r, q) {
+  const names = await lookupNames(q.addresses.map((a) => a.address));
   await modal("Quota usage of " + (r.comment || "rule #" + r.id), h("div", null,
     h("p", { class: "muted" }, "Each " + (r.quota.per_source ? "source" : "destination") + " has " + fmtBytes(r.quota.bytes) + "."),
     table([
-      { label: "Address", render: (a) => h("span", { class: "mono" }, a.address) },
+      { label: "Address", render: (a) => h("span", { class: "mono" }, named(names, a.address)) },
       { label: "Used", render: (a) => fmtBytes(a.used) },
       { label: "", render: (a) => usageBar(a.used, r.quota.bytes) },
     ], q.addresses)), [{ label: "Close", value: null }], { wide: true });
diff --git a/internal/web/static/assets/pages/stats.js b/internal/web/static/assets/pages/stats.js
index 6bd1c01..e646d81 100644
--- a/internal/web/static/assets/pages/stats.js
+++ b/internal/web/static/assets/pages/stats.js
@@ -3,6 +3,7 @@
 import { h, mount, fmtTime, errorBox } from "../ui.js";
 import { get } from "../api.js";
 import { lineChart, chartCard, legend, timeTable, heatmap, heatmapTable, barList, compact, stepSeconds, endLabelWidth } from "../charts.js";
+import { withNames } from "../widgets.js";
 
 const ranges = [["1h", "1 hour"], ["6h", "6 hours"], ["24h", "24 hours"], ["7d", "7 days"], ["30d", "30 days"], ["90d", "90 days"], ["365d", "a year"]];
 const rangeSecs = { "1h": 3600, "6h": 6 * 3600, "24h": 86400, "7d": 7 * 86400, "30d": 30 * 86400, "90d": 90 * 86400, "365d": 365 * 86400 };
@@ -142,6 +143,7 @@ async function loadAll(since, heatSince) {
     get("/stats/timeline", { since, keys: "g:conntrack,g:conntrack_max,g:mem,g:rss,g:load,g:cpu" }),
     get("/stats/timeline", { since, keys: "quota:*" }),
   ]);
+  await withNames(summary.devices_down, summary.devices_up, summary.blocked_sources);
   return { summary, zones, traffic, drops, heat, hits, gauges,
     quotas: quotas.series.map((x) => ({ key: x.key.slice(6), count: x.values.reduce((a, v) => a + Math.max(v, 0), 0) })).filter((e) => e.count > 0).sort((a, b) => b.count - a.count) };
 }
diff --git a/internal/web/static/assets/style.css b/internal/web/static/assets/style.css
index 7a11ecb..5f214d5 100644
--- a/internal/web/static/assets/style.css
+++ b/internal/web/static/assets/style.css
@@ -85,6 +85,7 @@ h1 { font-size: 20px; margin: 0 0 4px; }
 h2 { font-size: 16px; margin: 18px 0 8px; }
 h3 { font-size: 14px; margin: 14px 0 6px; }
 .muted { color: var(--muted); }
+.host-name { font-weight: 600; }
 .small { font-size: 12px; }
 .nowrap { white-space: nowrap; }
 .warn-text { color: var(--warn); }
diff --git a/internal/web/static/assets/widgets.js b/internal/web/static/assets/widgets.js
index a35f2f4..c1f1f03 100644
--- a/internal/web/static/assets/widgets.js
+++ b/internal/web/static/assets/widgets.js
@@ -1,7 +1,7 @@
 // Widgets shared by several pages: list editors with suggestions, the
 // match editor of rules and NAT, descriptions, hit counts, durations.
 import { h, input, select, field, checkbox } from "./ui.js";
-import { get } from "./api.js";
+import { get, api } from "./api.js";
 
 // ---- durations
 
@@ -163,6 +163,27 @@ export function usageBar(used, total) {
   return h("div", { class: "usage" }, h("div", { class: "usage-bar" + (used >= total ? " full" : "") }, seg));
 }
 
+// lookupNames asks for inside addresses' names (docs/configuration.md):
+// {address: name}, {} when names are off or can't be had.
+export async function lookupNames(addrs) {
+  const list = [...new Set(addrs.filter(Boolean))];
+  if (!list.length) return {};
+  try { return (await api("POST", "/names", { body: { addresses: list } })).names || {}; } catch { return {}; }
+}
+
+// named shows an address (or text with it, such as address:port) after
+// its name's first label; the whole name is in the tooltip.
+export function named(names, addr, text = addr) {
+  const n = names[addr];
+  return n ? h("span", { title: n + " (" + addr + ")" }, h("span", { class: "host-name" }, n.split(".")[0]), " ", h("span", { class: "muted" }, text)) : text;
+}
+
+// withNames sets each top-list entry's name from its key (an address).
+export async function withNames(...lists) {
+  const names = await lookupNames(lists.flat().map((e) => e.key));
+  for (const e of lists.flat()) if (names[e.key]) e.name = names[e.key].split(".")[0];
+}
+
 // quotas loads what the rules' quotas used, by rule ID ({} without
 // log:read).
 export async function quotas() {
diff --git a/scripts/e2e.sh b/scripts/e2e.sh
index 8978bd1..2487bdc 100755
--- a/scripts/e2e.sh
+++ b/scripts/e2e.sh
@@ -55,6 +55,9 @@ docker run -d --name ${P}-router --hostname router --cap-add NET_ADMIN $sysctls
 	--network ${P}-wan --ip $WAN4 --ip6 $WAN6 -v "$WORK:/w" "$IMAGE" sleep infinity >/dev/null || exit 1
 docker network connect --ip $LAN4 --ip6 $LAN6 ${P}-lan ${P}-router || exit 1
 docker network connect --ip 10.88.50.1 ${P}-wg ${P}-router || exit 1
+# The client has a name for housecarld's reverse lookups (/etc/hosts
+# here, a PTR record in real life); the addresses outside get none.
+docker exec ${P}-router sh -c "echo '$CLIENT4 e2e-client.lab' >> /etc/hosts" || exit 1
 # The router's interfaces get the names of the real one: wan, enp2s0, wg0
 # (attached in that order: eth0, eth1, eth2).
 docker exec ${P}-router sh -c 'for p in eth0:wan eth1:enp2s0 eth2:wg0; do i=${p%:*} n=${p#*:}; ip link set $i down && ip link set $i name $n && ip link set $n up; done
@@ -319,11 +322,11 @@ send 2000000 >/dev/null 2>&1
 run "used up: the device is cut off" 1 send 1000
 run "the usage" 0 H quotas
 contains "e2e quota.*1.0 MB each.*by hand"
-contains "$CLIENT4  *1\.[0-9] MB"
+contains "$CLIENT4 (e2e-client)  *1\.[0-9] MB"
 stop; start
 run "after a restart, still used up" 1 send 1000
 run "the usage after a restart" 0 H quotas
-contains "$CLIENT4  *1\.[0-9] MB"
+contains "$CLIENT4 (e2e-client)  *1\.[0-9] MB"
 run "reset by hand" 0 H rule reset-quota "$QR"
 run "the device is back" 0 send 1000
 run "the reset is audited" 0 H audit --action quota.
@@ -362,7 +365,8 @@ contains "Dropped:  *[1-9]"
 run "traffic per zone over time" 0 H stats traffic --since 1h --step 1m
 contains "wan ↓"
 run "the devices" 0 H stats top devices --since 1h
-contains "^$CLIENT4  *[0-9.]* KB  *[0-9.]* KB"
+contains "^$CLIENT4 (e2e-client)  *[0-9.]* KB  *[0-9.]* KB"
+run "each device once" 0 sh -c "docker exec ${P}-router /w/hc stats top devices --since 1h | grep -c '^$CLIENT4 ' | grep -qx 1"
 run "the sources blocked" 0 H stats top blocked --since 1h
 contains "^$NET4  *[1-9]"
 run "what they tried" 0 H stats top tried --since 1h
@@ -379,6 +383,8 @@ contains "^[0-9-]* [0-9:]*  *[0-9]*  *[0-9]*"
 docker exec -d ${P}-client sh -c "sleep 30 | nc $NET4 9000"
 sleep 1
 run "the connection is tracked" 0 H connections --search "$CLIENT4 :9000"
+contains "$CLIENT4:[0-9]* (e2e-client)  *$NET4:9000  *as $WAN4"
+run "without names" 0 H connections --search "$CLIENT4 :9000" --no-names
 contains "$CLIENT4:[0-9]*  *$NET4:9000  *as $WAN4"
 run "closed" 0 H connections close --search "$CLIENT4 :9000" -y
 contains "closed [1-9][0-9]* connection"