feat(dhcp): DHCPv4-Server via Kea (kea-dhcp4-server) — v1.2.92

Verwalteter DHCPv4-Server analog Unbound/Squid/Chrony. - Migration 0041: dhcp_settings (singleton, node-lokal), dhcp_subnets, dhcp_reservations. - internal/kea: Renderer baut Kea-JSON via Go-Struct→Marshal (garantiert valide), managed /etc/edgeguard/kea/kea-dhcp4.conf (Symlink von /etc/kea), Service-Lifecycle an enabled gekoppelt (default AUS, kein rogue DHCP). Interface per NAME (cluster-sicher, kein node-lokaler FK). - internal/services/dhcp + internal/handlers/dhcp.go: Settings + Subnet/Reservation-CRUD, Validierung (CIDR/IP/MAC/interface exists). - configgen: Stop/Enable/DisableService. Firewall: AutoFWRule.Iface → udp/67 pro LAN-Interface gescopt (kein WAN). Cluster: subnets/reservations repliziert (hashSpec), dhcp_settings node-lokal (localOnlyTables). - main.go + render.go + WithAllReloaders Wiring. Packaging: kea-dhcp4-server Dependency, /etc/edgeguard/kea Dir, Symlink, disable-on-install, sudoers (restart/stop/enable/disable). - UI: DHCP-Seite (Settings + Subnets + Reservierungen pro Subnet), Route/Nav/i18n de/en, HA-Warnung 'nur auf einer Node aktivieren'. - Tests (guarded EG_FWTEST_DSN): Kea-Renderer gegen DB (valides JSON + Felder), FW-Auto-Rule-Iface inkl. nft -c. Scope v1: DHCPv4. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-05 18:56:30 +02:00
parent 3a707e2e3f
commit bac7c7e349
24 changed files with 1666 additions and 6 deletions
--- a/2
+++ b/2
@@ -1 +1 @@
-1.2.91
+1.2.92
--- a/cmd/edgeguard-api/main.go
+++ b/cmd/edgeguard-api/main.go
@@ -28,6 +28,7 @@ import (
 	squidrender "git.netcell-it.de/projekte/edgeguard-native/internal/squid"
 	unboundrender "git.netcell-it.de/projekte/edgeguard-native/internal/unbound"
 	wgrender "git.netcell-it.de/projekte/edgeguard-native/internal/wireguard"
+	kearender "git.netcell-it.de/projekte/edgeguard-native/internal/kea"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/handlers/response"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/acme"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/alerts"
@@ -58,6 +59,7 @@ import (
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/setup"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/tlscerts"
 	wgsvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/wireguard"
+	dhcpsvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/dhcp"
 	oidcsvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/oidc"
 	usersvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/users"
 	wafsvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/waf"
@@ -445,6 +447,12 @@ func main() {
 		}
 		handlers.NewNTPHandler(ntpRepo, auditRepo, nodeID, withFW(chronyReloader)).Register(authed)

+		// DHCP (Kea) — re-render kea-dhcp4.conf + manage service lifecycle.
+		keaReloader := func(ctx context.Context) error {
+			return kearender.New(pool).Render(ctx)
+		}
+		handlers.NewDHCPHandler(dhcpsvc.New(pool), auditRepo, nodeID, withFW(keaReloader)).Register(authed)
+
 		// Wire all service reloaders into systemHdl so RenderConfigs
 		// re-renders every service from DB state in one shot.
 		systemHdl.WithAllReloaders(map[string]func(context.Context) error{
@@ -453,6 +461,7 @@ func main() {
 			"squid":     squidReloader,
 			"unbound":   unboundReloader,
 			"chrony":    chronyReloader,
+			"kea":       keaReloader,
 		})

 		// License — node-local key store + DB-mirror of last verify
--- a/cmd/edgeguard-ctl/cluster_replication.go
+++ b/cmd/edgeguard-ctl/cluster_replication.go
@@ -79,6 +79,7 @@ var localOnlyTables = []string{
 	"cluster_settings",   // VIP-Interface kann pro Node unterschiedlich sein
 	"dns_settings",       // listen_addresses ist node-spezifisch
 	"ntp_settings",       // listen_addresses ist node-spezifisch
+	"dhcp_settings",      // ob DIESE Node DHCP betreibt (Dual-DHCP vermeiden)
 	"system_settings",    // Hostname, Maintenance-Mode etc.
 	"join_tokens_used",   // Token-Tracking nur auf Primary relevant
 	"audit_log",          // Lokales Audit-Protokoll
--- a/cmd/edgeguard-ctl/render.go
+++ b/cmd/edgeguard-ctl/render.go
@@ -8,6 +8,7 @@ import (
 	"time"

 	"git.netcell-it.de/projekte/edgeguard-native/internal/chrony"
+	"git.netcell-it.de/projekte/edgeguard-native/internal/kea"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/configgen"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/database"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/firewall"
@@ -61,9 +62,11 @@ func cmdRenderConfig(args []string) int {
 	wg := wireguard.New(pool, secrets.New(""))
 	ub := unbound.New(pool)
 	cn := chrony.New(pool)
+	ke := kea.New(pool)
 	if skipReload {
 		hap.SkipReload = true
 		fw.SkipReload = true
+		ke.SkipReload = true
 	}

 	// keepalived: Node-ID aus node.conf für Prioritäts-Berechnung
@@ -72,7 +75,7 @@ func cmdRenderConfig(args []string) int {
 		ka = keepalived.New(pool, lc.NodeID)
 	}

-	gens := []configgen.Generator{hap, fw, sq, wg, ub, cn}
+	gens := []configgen.Generator{hap, fw, sq, wg, ub, cn, ke}
 	if ka != nil {
 		gens = append(gens, ka)
 	}
--- a/internal/cluster/confighash.go
+++ b/internal/cluster/confighash.go
@@ -71,6 +71,11 @@ var hashSpec = []hashTable{

 	{Name: "ntp_pools", MigrationDefault: true},

+	// DHCP: Subnets + Reservierungen sind geteilte Config (repliziert).
+	// dhcp_settings ist node-lokal (ob DIESE Node DHCP betreibt) → NICHT hier.
+	{Name: "dhcp_subnets"},
+	{Name: "dhcp_reservations"},
+
 	// network_interfaces + ip_addresses sind BEWUSST NICHT im Drift-Hash.
 	// Sie stehen in cluster_replication.go localOnlyTables, werden also NICHT
 	// repliziert und sind per Design node-spezifisch (jede Node hat eigene
--- a/internal/configgen/configgen.go
+++ b/internal/configgen/configgen.go
@@ -99,6 +99,33 @@ func RestartService(name string) error {
 	return nil
 }

+// StopService runs `sudo -n systemctl stop <name>.service`.
+func StopService(name string) error {
+	cmd := exec.Command("sudo", "-n", "/usr/bin/systemctl", "stop", name+".service")
+	if out, err := cmd.CombinedOutput(); err != nil {
+		return fmt.Errorf("sudo systemctl stop %s.service: %w (output: %s)", name, err, strings.TrimSpace(string(out)))
+	}
+	return nil
+}
+
+// EnableService runs `sudo -n systemctl enable <name>.service` (boot-persistent).
+func EnableService(name string) error {
+	cmd := exec.Command("sudo", "-n", "/usr/bin/systemctl", "enable", name+".service")
+	if out, err := cmd.CombinedOutput(); err != nil {
+		return fmt.Errorf("sudo systemctl enable %s.service: %w (output: %s)", name, err, strings.TrimSpace(string(out)))
+	}
+	return nil
+}
+
+// DisableService runs `sudo -n systemctl disable <name>.service`.
+func DisableService(name string) error {
+	cmd := exec.Command("sudo", "-n", "/usr/bin/systemctl", "disable", name+".service")
+	if out, err := cmd.CombinedOutput(); err != nil {
+		return fmt.Errorf("sudo systemctl disable %s.service: %w (output: %s)", name, err, strings.TrimSpace(string(out)))
+	}
+	return nil
+}
+
 // EtcEdgeguard is the on-target config root. Templated path used by
 // all renderers — never let renderers hard-code their own.
 const EtcEdgeguard = "/etc/edgeguard"
--- a/internal/database/migrations/0041_dhcp.sql
+++ b/internal/database/migrations/0041_dhcp.sql
@@ -0,0 +1,62 @@
+-- +goose Up
+-- +goose StatementBegin
+
+-- DHCP (Kea) — globale Singleton-Settings (node-lokal, wie dns_settings/
+-- ntp_settings: ob DIESE Node DHCP betreibt). Subnets/Reservierungen sind
+-- geteilte Config und werden repliziert.
+CREATE TABLE IF NOT EXISTS dhcp_settings (
+    id             INTEGER     PRIMARY KEY DEFAULT 1,
+    enabled        BOOLEAN     NOT NULL DEFAULT false,
+    default_lease  INTEGER     NOT NULL DEFAULT 3600,
+    max_lease      INTEGER     NOT NULL DEFAULT 7200,
+    domain_name    TEXT        NOT NULL DEFAULT '',
+    dns_servers    TEXT        NOT NULL DEFAULT '',
+    created_at     TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at     TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    CONSTRAINT dhcp_settings_singleton CHECK (id = 1)
+);
+INSERT INTO dhcp_settings (id) VALUES (1) ON CONFLICT DO NOTHING;
+
+-- Subnets: an ein Interface per NAME gebunden (nicht per node-lokaler FK,
+-- damit die Replikation nicht an divergierenden interface_id bricht).
+CREATE TABLE IF NOT EXISTS dhcp_subnets (
+    id             BIGSERIAL   PRIMARY KEY,
+    name           TEXT        NOT NULL,
+    interface_name TEXT        NOT NULL,
+    subnet_cidr    TEXT        NOT NULL,
+    pool_start     TEXT        NOT NULL DEFAULT '',
+    pool_end       TEXT        NOT NULL DEFAULT '',
+    gateway        TEXT        NOT NULL DEFAULT '',
+    dns_servers    TEXT        NOT NULL DEFAULT '',
+    lease_time     INTEGER,
+    active         BOOLEAN     NOT NULL DEFAULT true,
+    description    TEXT        NOT NULL DEFAULT '',
+    created_at     TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at     TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    CONSTRAINT dhcp_subnets_name_unique UNIQUE (name)
+);
+
+CREATE TABLE IF NOT EXISTS dhcp_reservations (
+    id          BIGSERIAL   PRIMARY KEY,
+    subnet_id   BIGINT      NOT NULL REFERENCES dhcp_subnets(id) ON DELETE CASCADE,
+    name        TEXT        NOT NULL DEFAULT '',
+    mac_address TEXT        NOT NULL,
+    ip_address  TEXT        NOT NULL,
+    hostname    TEXT        NOT NULL DEFAULT '',
+    active      BOOLEAN     NOT NULL DEFAULT true,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    CONSTRAINT dhcp_reservations_subnet_mac_unique UNIQUE (subnet_id, mac_address)
+);
+CREATE INDEX IF NOT EXISTS idx_dhcp_reservations_subnet ON dhcp_reservations(subnet_id);
+
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+
+DROP TABLE IF EXISTS dhcp_reservations;
+DROP TABLE IF EXISTS dhcp_subnets;
+DROP TABLE IF EXISTS dhcp_settings;
+
+-- +goose StatementEnd
--- a/internal/firewall/firewall.go
+++ b/internal/firewall/firewall.go
@@ -150,6 +150,7 @@ type AutoFWRule struct {
 	Proto   string
 	Port    int
 	DstIP   string
+	Iface   string // optional: scope auf ein iifname (z.B. DHCP udp/67 nur auf LAN)
 	Comment string
 }

@@ -417,6 +418,22 @@ func (g *Generator) loadAutoRules(ctx context.Context) []AutoFWRule {
 		}
 	}

+	// DHCP (Kea): wenn auf DIESER Node aktiviert → udp/67 pro aktivem
+	// Subnet-Interface (gescopt auf die LAN-iface, NICHT global/WAN).
+	var dhcpEnabled bool
+	if err := g.Pool.QueryRow(ctx, `SELECT enabled FROM dhcp_settings WHERE id=1`).Scan(&dhcpEnabled); err == nil && dhcpEnabled {
+		rows, err := g.Pool.Query(ctx, `SELECT DISTINCT interface_name FROM dhcp_subnets WHERE active AND interface_name <> ''`)
+		if err == nil {
+			defer rows.Close()
+			for rows.Next() {
+				var iface string
+				if rows.Scan(&iface) == nil && iface != "" {
+					out = append(out, AutoFWRule{Proto: "udp", Port: 67, Iface: iface, Comment: "DHCP (Kea) auf " + iface})
+				}
+			}
+		}
+	}
+
 	return out
 }

--- a/internal/firewall/firewall_autorule_test.go
+++ b/internal/firewall/firewall_autorule_test.go
@@ -0,0 +1,59 @@
+package firewall
+
+import (
+	"bytes"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+// TestTemplate_autoRuleIface prüft, dass eine Auto-Rule mit Iface als
+// `iifname "<x>"`-gescopte Zeile rendert (DHCP udp/67 auf LAN) und dass
+// DstIP-basierte Auto-Rules unverändert bleiben.
+func TestTemplate_autoRuleIface(t *testing.T) {
+	view := &View{
+		AutoRules: []AutoFWRule{
+			{Proto: "udp", Port: 67, Iface: "eth1", Comment: "DHCP (Kea) auf eth1"},
+			{Proto: "udp", Port: 53, DstIP: "10.0.0.1", Comment: "DNS"},
+		},
+	}
+	var buf bytes.Buffer
+	if err := tpl.Execute(&buf, view); err != nil {
+		t.Fatalf("template execute: %v", err)
+	}
+	out := buf.String()
+
+	if !strings.Contains(out, `iifname "eth1" udp dport 67 accept comment "auto: DHCP (Kea) auf eth1"`) {
+		t.Errorf("missing iface-scoped DHCP auto-rule\n----\n%s", out)
+	}
+	// Regression: DstIP-Auto-Rule ohne Iface bleibt unverändert.
+	if !strings.Contains(out, `ip daddr 10.0.0.1 udp dport 53 accept`) {
+		t.Errorf("DstIP auto-rule changed\n----\n%s", out)
+	}
+
+	// Echte nft-Syntaxvalidierung (braucht root → via sudo, sonst skip).
+	nft, err := exec.LookPath("nft")
+	if err != nil {
+		t.Skip("nft not in PATH")
+	}
+	f, err := os.CreateTemp(t.TempDir(), "autorule-*.nft")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = f.WriteString(out)
+	f.Close()
+	var cmd *exec.Cmd
+	if os.Geteuid() == 0 {
+		cmd = exec.Command(nft, "-c", "-f", f.Name())
+	} else {
+		cmd = exec.Command("sudo", "-n", nft, "-c", "-f", f.Name())
+	}
+	if combined, err := cmd.CombinedOutput(); err != nil {
+		msg := string(combined)
+		if strings.Contains(msg, "Operation not permitted") || strings.Contains(msg, "password is required") {
+			t.Skipf("nft -c needs root: %s", strings.TrimSpace(msg))
+		}
+		t.Fatalf("nft -c rejected ruleset: %v\n%s\n----\n%s", err, combined, out)
+	}
+}
--- a/internal/firewall/firewall_e2e_test.go
+++ b/internal/firewall/firewall_e2e_test.go
@@ -6,6 +6,7 @@ import (
 	"os/exec"
 	"strings"
 	"testing"
+	"time"

 	"git.netcell-it.de/projekte/edgeguard-native/internal/database"
 )
@@ -19,8 +20,17 @@ func TestE2E_IPv6Render(t *testing.T) {
 		t.Skip("set EG_FWTEST_DSN to run the firewall end-to-end test")
 	}
 	ctx := context.Background()
-	if err := database.Migrate(ctx, dsn); err != nil {
-		t.Fatalf("migrate: %v", err)
+	// Retry: goose-Erst-Apply ist nicht concurrency-safe, wenn mehrere
+	// guarded Test-Pakete dieselbe frische DB parallel migrieren.
+	var mErr error
+	for i := 0; i < 3; i++ {
+		if mErr = database.Migrate(ctx, dsn); mErr == nil {
+			break
+		}
+		time.Sleep(700 * time.Millisecond)
+	}
+	if mErr != nil {
+		t.Fatalf("migrate: %v", mErr)
 	}
 	pool, err := database.Open(ctx, dsn)
 	if err != nil {
--- a/internal/firewall/ruleset.nft.tpl
+++ b/internal/firewall/ruleset.nft.tpl
@@ -61,7 +61,7 @@ table inet edgeguard {
        # editiert diese nicht. Wenn der Service entfernt/disabled
        # wird, ist die Rule beim nächsten Render weg.
 {{range .AutoRules}}
-        {{if .DstIP}}ip daddr {{.DstIP}} {{end}}{{.Proto}} dport {{.Port}} accept comment "auto: {{.Comment}}"
+        {{if .Iface}}iifname "{{.Iface}}" {{end}}{{if .DstIP}}ip daddr {{.DstIP}} {{end}}{{.Proto}} dport {{.Port}} accept comment "auto: {{.Comment}}"
 {{end}}

        # ── Operator-defined rules ──
--- a/internal/handlers/dhcp.go
+++ b/internal/handlers/dhcp.go
@@ -0,0 +1,346 @@
+package handlers
+
+import (
+	"context"
+	"errors"
+	"log/slog"
+	"net"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+
+	"git.netcell-it.de/projekte/edgeguard-native/internal/handlers/response"
+	"git.netcell-it.de/projekte/edgeguard-native/internal/models"
+	"git.netcell-it.de/projekte/edgeguard-native/internal/services/audit"
+	dhcpsvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/dhcp"
+)
+
+// DHCPHandler exposes /api/v1/dhcp/{settings,subnets,reservations} for
+// the Kea DHCPv4 server.
+type DHCPHandler struct {
+	Repo     *dhcpsvc.Repo
+	Audit    *audit.Repo
+	NodeID   string
+	Reloader func(ctx context.Context) error
+}
+
+func NewDHCPHandler(repo *dhcpsvc.Repo, a *audit.Repo, nodeID string, reloader func(context.Context) error) *DHCPHandler {
+	return &DHCPHandler{Repo: repo, Audit: a, NodeID: nodeID, Reloader: reloader}
+}
+
+func (h *DHCPHandler) reload(ctx context.Context, op string) {
+	if h.Reloader == nil {
+		return
+	}
+	if err := h.Reloader(ctx); err != nil {
+		slog.Warn("kea: reload after mutation failed", "op", op, "error", err)
+	}
+}
+
+func (h *DHCPHandler) Register(rg *gin.RouterGroup) {
+	g := rg.Group("/dhcp")
+	g.GET("/settings", h.GetSettings)
+	g.PUT("/settings", h.UpdateSettings)
+
+	s := g.Group("/subnets")
+	s.GET("", h.ListSubnets)
+	s.POST("", h.CreateSubnet)
+	s.GET("/:id", h.GetSubnet)
+	s.PUT("/:id", h.UpdateSubnet)
+	s.DELETE("/:id", h.DeleteSubnet)
+	s.GET("/:id/reservations", h.ListReservationsForSubnet)
+	s.POST("/:id/reservations", h.CreateReservation)
+
+	r := g.Group("/reservations")
+	r.GET("", h.ListAllReservations)
+	r.GET("/:id", h.GetReservation)
+	r.PUT("/:id", h.UpdateReservation)
+	r.DELETE("/:id", h.DeleteReservation)
+}
+
+// ── Settings ─────────────────────────────────────────────────────────
+
+func (h *DHCPHandler) GetSettings(c *gin.Context) {
+	s, err := h.Repo.GetSettings(c.Request.Context())
+	if err != nil {
+		response.Internal(c, err)
+		return
+	}
+	response.OK(c, s)
+}
+
+func (h *DHCPHandler) UpdateSettings(c *gin.Context) {
+	var req models.DHCPSettings
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	if req.DefaultLease <= 0 {
+		req.DefaultLease = 3600
+	}
+	if req.MaxLease < req.DefaultLease {
+		req.MaxLease = req.DefaultLease
+	}
+	if err := validateIPList(req.DNSServers); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	out, err := h.Repo.UpdateSettings(c.Request.Context(), req)
+	if err != nil {
+		response.Internal(c, err)
+		return
+	}
+	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "dhcp.settings.update", "",
+		gin.H{"enabled": out.Enabled}, h.NodeID)
+	response.OK(c, out)
+	h.reload(c.Request.Context(), "settings.update")
+}
+
+// ── Subnets ──────────────────────────────────────────────────────────
+
+func (h *DHCPHandler) ListSubnets(c *gin.Context) {
+	out, err := h.Repo.ListSubnets(c.Request.Context())
+	if err != nil {
+		response.Internal(c, err)
+		return
+	}
+	response.OK(c, gin.H{"subnets": out})
+}
+
+func (h *DHCPHandler) GetSubnet(c *gin.Context) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	s, err := h.Repo.GetSubnet(c.Request.Context(), id)
+	if err != nil {
+		h.subnetErr(c, err)
+		return
+	}
+	response.OK(c, s)
+}
+
+func (h *DHCPHandler) CreateSubnet(c *gin.Context) {
+	var req models.DHCPSubnet
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	if err := h.validateSubnet(c, &req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	out, err := h.Repo.CreateSubnet(c.Request.Context(), req)
+	if err != nil {
+		response.Internal(c, err)
+		return
+	}
+	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "dhcp.subnet.create", out.Name, out, h.NodeID)
+	response.Created(c, out)
+	h.reload(c.Request.Context(), "subnet.create")
+}
+
+func (h *DHCPHandler) UpdateSubnet(c *gin.Context) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	var req models.DHCPSubnet
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	if err := h.validateSubnet(c, &req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	out, err := h.Repo.UpdateSubnet(c.Request.Context(), id, req)
+	if err != nil {
+		h.subnetErr(c, err)
+		return
+	}
+	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "dhcp.subnet.update", out.Name, out, h.NodeID)
+	response.OK(c, out)
+	h.reload(c.Request.Context(), "subnet.update")
+}
+
+func (h *DHCPHandler) DeleteSubnet(c *gin.Context) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	if err := h.Repo.DeleteSubnet(c.Request.Context(), id); err != nil {
+		h.subnetErr(c, err)
+		return
+	}
+	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "dhcp.subnet.delete", "", gin.H{"id": id}, h.NodeID)
+	response.OK(c, gin.H{"ok": true})
+	h.reload(c.Request.Context(), "subnet.delete")
+}
+
+// ── Reservations ─────────────────────────────────────────────────────
+
+func (h *DHCPHandler) ListAllReservations(c *gin.Context) {
+	out, err := h.Repo.ListAllReservations(c.Request.Context())
+	if err != nil {
+		response.Internal(c, err)
+		return
+	}
+	response.OK(c, gin.H{"reservations": out})
+}
+
+func (h *DHCPHandler) ListReservationsForSubnet(c *gin.Context) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	out, err := h.Repo.ListReservationsForSubnet(c.Request.Context(), id)
+	if err != nil {
+		response.Internal(c, err)
+		return
+	}
+	response.OK(c, gin.H{"reservations": out})
+}
+
+func (h *DHCPHandler) GetReservation(c *gin.Context) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	v, err := h.Repo.GetReservation(c.Request.Context(), id)
+	if err != nil {
+		h.resvErr(c, err)
+		return
+	}
+	response.OK(c, v)
+}
+
+func (h *DHCPHandler) CreateReservation(c *gin.Context) {
+	subnetID, ok := parseID(c)
+	if !ok {
+		return
+	}
+	var req models.DHCPReservation
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	req.SubnetID = subnetID
+	if err := validateReservation(&req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	out, err := h.Repo.CreateReservation(c.Request.Context(), req)
+	if err != nil {
+		response.Internal(c, err)
+		return
+	}
+	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "dhcp.reservation.create", out.MACAddress, out, h.NodeID)
+	response.Created(c, out)
+	h.reload(c.Request.Context(), "reservation.create")
+}
+
+func (h *DHCPHandler) UpdateReservation(c *gin.Context) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	var req models.DHCPReservation
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	if err := validateReservation(&req); err != nil {
+		response.BadRequest(c, err)
+		return
+	}
+	out, err := h.Repo.UpdateReservation(c.Request.Context(), id, req)
+	if err != nil {
+		h.resvErr(c, err)
+		return
+	}
+	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "dhcp.reservation.update", out.MACAddress, out, h.NodeID)
+	response.OK(c, out)
+	h.reload(c.Request.Context(), "reservation.update")
+}
+
+func (h *DHCPHandler) DeleteReservation(c *gin.Context) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	if err := h.Repo.DeleteReservation(c.Request.Context(), id); err != nil {
+		h.resvErr(c, err)
+		return
+	}
+	_ = h.Audit.Log(c.Request.Context(), actorOf(c), "dhcp.reservation.delete", "", gin.H{"id": id}, h.NodeID)
+	response.OK(c, gin.H{"ok": true})
+	h.reload(c.Request.Context(), "reservation.delete")
+}
+
+// ── Validation + error mapping ───────────────────────────────────────
+
+func (h *DHCPHandler) validateSubnet(c *gin.Context, s *models.DHCPSubnet) error {
+	s.Name = strings.TrimSpace(s.Name)
+	s.InterfaceName = strings.TrimSpace(s.InterfaceName)
+	if s.Name == "" {
+		return errors.New("name ist erforderlich")
+	}
+	if s.InterfaceName == "" {
+		return errors.New("interface_name ist erforderlich")
+	}
+	if exists, err := h.Repo.InterfaceExists(c.Request.Context(), s.InterfaceName); err == nil && !exists {
+		return errors.New("interface_name existiert nicht: " + s.InterfaceName)
+	}
+	if _, _, err := net.ParseCIDR(s.SubnetCIDR); err != nil {
+		return errors.New("subnet_cidr ist kein gültiges CIDR: " + s.SubnetCIDR)
+	}
+	if (s.PoolStart == "") != (s.PoolEnd == "") {
+		return errors.New("pool_start und pool_end müssen beide gesetzt sein (oder beide leer)")
+	}
+	for _, ip := range []string{s.PoolStart, s.PoolEnd, s.Gateway} {
+		if ip != "" && net.ParseIP(ip) == nil {
+			return errors.New("ungültige IP-Adresse: " + ip)
+		}
+	}
+	return validateIPList(s.DNSServers)
+}
+
+func validateReservation(r *models.DHCPReservation) error {
+	r.MACAddress = strings.TrimSpace(strings.ToLower(r.MACAddress))
+	r.IPAddress = strings.TrimSpace(r.IPAddress)
+	if _, err := net.ParseMAC(r.MACAddress); err != nil {
+		return errors.New("mac_address ist ungültig: " + r.MACAddress)
+	}
+	if net.ParseIP(r.IPAddress) == nil {
+		return errors.New("ip_address ist ungültig: " + r.IPAddress)
+	}
+	return nil
+}
+
+// validateIPList prüft eine optionale Komma-Liste von IPs.
+func validateIPList(csv string) error {
+	for _, p := range strings.Split(csv, ",") {
+		p = strings.TrimSpace(p)
+		if p != "" && net.ParseIP(p) == nil {
+			return errors.New("ungültige IP in dns_servers: " + p)
+		}
+	}
+	return nil
+}
+
+func (h *DHCPHandler) subnetErr(c *gin.Context, err error) {
+	if errors.Is(err, dhcpsvc.ErrSubnetNotFound) {
+		response.NotFound(c, err)
+		return
+	}
+	response.Internal(c, err)
+}
+
+func (h *DHCPHandler) resvErr(c *gin.Context, err error) {
+	if errors.Is(err, dhcpsvc.ErrReservationNotFound) {
+		response.NotFound(c, err)
+		return
+	}
+	response.Internal(c, err)
+}
--- a/internal/kea/kea.go
+++ b/internal/kea/kea.go
@@ -0,0 +1,235 @@
+// Package kea renders the Kea DHCPv4 server config from the dhcp_*
+// tables and manages the kea-dhcp4-server service lifecycle.
+//
+// The config is built as a Go struct and json-marshalled (NOT a text
+// template) so the output is always syntactically valid JSON. Managed
+// at /etc/edgeguard/kea/kea-dhcp4.conf (edgeguard-owned); postinst
+// symlinks /etc/kea/kea-dhcp4.conf to it.
+//
+// Safety: the service runs ONLY when dhcp_settings.enabled is true on
+// THIS node (a DHCP server is network-sensitive; default off). enabled
+// → enable + restart; disabled → disable + stop.
+package kea
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"git.netcell-it.de/projekte/edgeguard-native/internal/configgen"
+	dhcpsvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/dhcp"
+)
+
+const (
+	ConfPath    = configgen.EtcEdgeguard + "/kea/kea-dhcp4.conf"
+	serviceName = "kea-dhcp4-server"
+	leaseFile   = "/var/lib/kea/kea-leases4.csv"
+	keaBinary   = "/usr/sbin/kea-dhcp4"
+)
+
+type Generator struct {
+	Pool       *pgxpool.Pool
+	Repo       *dhcpsvc.Repo
+	SkipReload bool
+}
+
+func New(pool *pgxpool.Pool) *Generator {
+	return &Generator{Pool: pool, Repo: dhcpsvc.New(pool)}
+}
+
+func (g *Generator) Name() string { return "kea" }
+
+// ── Kea config JSON shape ────────────────────────────────────────────
+
+type keaConfig struct {
+	Dhcp4 dhcp4 `json:"Dhcp4"`
+}
+type dhcp4 struct {
+	InterfacesConfig ifcfg        `json:"interfaces-config"`
+	LeaseDatabase    leaseDB      `json:"lease-database"`
+	ValidLifetime    int          `json:"valid-lifetime"`
+	MaxValidLifetime int          `json:"max-valid-lifetime"`
+	OptionData       []optionData `json:"option-data,omitempty"`
+	Subnet4          []subnet4    `json:"subnet4"`
+	Loggers          []logger     `json:"loggers"`
+}
+type ifcfg struct {
+	Interfaces []string `json:"interfaces"`
+}
+type leaseDB struct {
+	Type    string `json:"type"`
+	Persist bool   `json:"persist"`
+	Name    string `json:"name"`
+}
+type optionData struct {
+	Name string `json:"name"`
+	Data string `json:"data"`
+}
+type subnet4 struct {
+	ID           int64         `json:"id"`
+	Subnet       string        `json:"subnet"`
+	Pools        []pool        `json:"pools,omitempty"`
+	OptionData   []optionData  `json:"option-data,omitempty"`
+	Reservations []reservation `json:"reservations,omitempty"`
+}
+type pool struct {
+	Pool string `json:"pool"`
+}
+type reservation struct {
+	HWAddress string `json:"hw-address"`
+	IPAddress string `json:"ip-address"`
+	Hostname  string `json:"hostname,omitempty"`
+}
+type logger struct {
+	Name          string   `json:"name"`
+	Severity      string   `json:"severity"`
+	OutputOptions []outOpt `json:"output_options"`
+}
+type outOpt struct {
+	Output string `json:"output"`
+}
+
+// buildConfig assembliert die Kea-Config aus dem DB-State.
+func (g *Generator) buildConfig(ctx context.Context) (*keaConfig, *bool, error) {
+	settings, err := g.Repo.GetSettings(ctx)
+	if err != nil {
+		return nil, nil, fmt.Errorf("get dhcp settings: %w", err)
+	}
+	subnets, err := g.Repo.ListSubnets(ctx)
+	if err != nil {
+		return nil, nil, fmt.Errorf("list subnets: %w", err)
+	}
+	resv, err := g.Repo.ListAllReservations(ctx)
+	if err != nil {
+		return nil, nil, fmt.Errorf("list reservations: %w", err)
+	}
+	bySubnet := map[int64][]reservation{}
+	for _, r := range resv {
+		if !r.Active {
+			continue
+		}
+		bySubnet[r.SubnetID] = append(bySubnet[r.SubnetID], reservation{
+			HWAddress: r.MACAddress, IPAddress: r.IPAddress, Hostname: r.Hostname,
+		})
+	}
+
+	ifaceSet := map[string]bool{}
+	var ifaces []string
+	var sn4 []subnet4
+
+	for _, s := range subnets {
+		if !s.Active {
+			continue
+		}
+		if !ifaceSet[s.InterfaceName] {
+			ifaceSet[s.InterfaceName] = true
+			ifaces = append(ifaces, s.InterfaceName)
+		}
+		sub := subnet4{ID: s.ID, Subnet: s.SubnetCIDR}
+		if s.PoolStart != "" && s.PoolEnd != "" {
+			sub.Pools = []pool{{Pool: s.PoolStart + " - " + s.PoolEnd}}
+		}
+		if s.Gateway != "" {
+			sub.OptionData = append(sub.OptionData, optionData{Name: "routers", Data: s.Gateway})
+		}
+		dns := s.DNSServers
+		if dns == "" {
+			dns = settings.DNSServers
+		}
+		if dns != "" {
+			sub.OptionData = append(sub.OptionData, optionData{Name: "domain-name-servers", Data: normalizeCSV(dns)})
+		}
+		sub.Reservations = bySubnet[s.ID]
+		sn4 = append(sn4, sub)
+	}
+
+	d := dhcp4{
+		InterfacesConfig: ifcfg{Interfaces: ifaces},
+		LeaseDatabase:    leaseDB{Type: "memfile", Persist: true, Name: leaseFile},
+		ValidLifetime:    settings.DefaultLease,
+		MaxValidLifetime: settings.MaxLease,
+		Subnet4:          sn4,
+		Loggers: []logger{{
+			Name: "kea-dhcp4", Severity: "INFO",
+			OutputOptions: []outOpt{{Output: "stdout"}},
+		}},
+	}
+	if settings.DNSServers != "" {
+		d.OptionData = append(d.OptionData, optionData{Name: "domain-name-servers", Data: normalizeCSV(settings.DNSServers)})
+	}
+	if settings.DomainName != "" {
+		d.OptionData = append(d.OptionData, optionData{Name: "domain-name", Data: settings.DomainName})
+	}
+	if d.Subnet4 == nil {
+		d.Subnet4 = []subnet4{}
+	}
+	return &keaConfig{Dhcp4: d}, &settings.Enabled, nil
+}
+
+func (g *Generator) RenderToString(ctx context.Context) (string, error) {
+	cfg, _, err := g.buildConfig(ctx)
+	if err != nil {
+		return "", err
+	}
+	b, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return "", err
+	}
+	return string(b) + "\n", nil
+}
+
+func (g *Generator) Render(ctx context.Context) error {
+	cfg, enabled, err := g.buildConfig(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Default-off / disabled: Service stoppen + disablen, nichts weiter.
+	if enabled == nil || !*enabled {
+		if g.SkipReload {
+			return nil
+		}
+		_ = configgen.DisableService(serviceName)
+		_ = configgen.StopService(serviceName)
+		return nil
+	}
+
+	b, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return err
+	}
+	if err := configgen.AtomicWrite(ConfPath, append(b, '\n'), 0o644); err != nil {
+		return fmt.Errorf("write kea config: %w", err)
+	}
+	if g.SkipReload {
+		return nil
+	}
+	// Best-effort Config-Test (verhindert Restart mit kaputter Semantik).
+	if _, statErr := os.Stat(keaBinary); statErr == nil {
+		if out, terr := exec.Command(keaBinary, "-t", ConfPath).CombinedOutput(); terr != nil {
+			return fmt.Errorf("kea-dhcp4 -t rejected config: %w (output: %s)", terr, strings.TrimSpace(string(out)))
+		}
+	}
+	if err := configgen.EnableService(serviceName); err != nil {
+		return err
+	}
+	return configgen.RestartService(serviceName)
+}
+
+// normalizeCSV trimmt Whitespace um Komma-getrennte Werte (Kea will
+// "a,b,c" ohne Leerzeichen-Toleranz-Probleme).
+func normalizeCSV(s string) string {
+	parts := strings.Split(s, ",")
+	out := make([]string, 0, len(parts))
+	for _, p := range parts {
+		if t := strings.TrimSpace(p); t != "" {
+			out = append(out, t)
+		}
+	}
+	return strings.Join(out, ",")
+}
--- a/internal/kea/kea_test.go
+++ b/internal/kea/kea_test.go
@@ -0,0 +1,89 @@
+package kea
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+
+	"git.netcell-it.de/projekte/edgeguard-native/internal/database"
+)
+
+// Guarded integration test: set EG_FWTEST_DSN (sonst skip).
+func TestRender_DHCPConfig(t *testing.T) {
+	dsn := os.Getenv("EG_FWTEST_DSN")
+	if dsn == "" {
+		t.Skip("set EG_FWTEST_DSN to run the kea renderer test")
+	}
+	ctx := context.Background()
+	var mErr error
+	for i := 0; i < 3; i++ {
+		if mErr = database.Migrate(ctx, dsn); mErr == nil {
+			break
+		}
+		time.Sleep(700 * time.Millisecond)
+	}
+	if mErr != nil {
+		t.Fatalf("migrate: %v", mErr)
+	}
+	pool, err := database.Open(ctx, dsn)
+	if err != nil {
+		t.Fatalf("open: %v", err)
+	}
+	defer pool.Close()
+
+	for _, q := range []string{
+		`DELETE FROM dhcp_reservations`,
+		`DELETE FROM dhcp_subnets`,
+		`UPDATE dhcp_settings SET enabled=true, default_lease=3600, max_lease=7200, domain_name='lan', dns_servers='1.1.1.1, 8.8.8.8' WHERE id=1`,
+	} {
+		if _, err := pool.Exec(ctx, q); err != nil {
+			t.Fatalf("seed (%s): %v", q, err)
+		}
+	}
+	var subID int64
+	if err := pool.QueryRow(ctx, `
+INSERT INTO dhcp_subnets (name, interface_name, subnet_cidr, pool_start, pool_end, gateway, dns_servers, active)
+VALUES ('lan','eth1','10.0.0.0/24','10.0.0.100','10.0.0.200','10.0.0.1','',true) RETURNING id`).Scan(&subID); err != nil {
+		t.Fatalf("seed subnet: %v", err)
+	}
+	if _, err := pool.Exec(ctx, `
+INSERT INTO dhcp_reservations (subnet_id, mac_address, ip_address, hostname, active)
+VALUES ($1,'aa:bb:cc:dd:ee:ff','10.0.0.50','printer',true)`, subID); err != nil {
+		t.Fatalf("seed reservation: %v", err)
+	}
+
+	out, err := New(pool).RenderToString(ctx)
+	if err != nil {
+		t.Fatalf("render: %v", err)
+	}
+	if !json.Valid([]byte(out)) {
+		t.Fatalf("rendered config is not valid JSON:\n%s", out)
+	}
+	for _, want := range []string{
+		`"10.0.0.0/24"`,
+		`"10.0.0.100 - 10.0.0.200"`,
+		`"aa:bb:cc:dd:ee:ff"`,
+		`"routers"`,
+		`"eth1"`,
+		`"hw-address"`,
+		`"valid-lifetime": 3600`,
+	} {
+		if !strings.Contains(out, want) {
+			t.Errorf("rendered config missing %q\n----\n%s", want, out)
+		}
+	}
+
+	// Best-effort: echte Kea-Validierung, falls die Binary da ist.
+	if _, statErr := os.Stat(keaBinary); statErr == nil {
+		f, _ := os.CreateTemp(t.TempDir(), "kea-*.conf")
+		_, _ = f.WriteString(out)
+		f.Close()
+		if combined, err := exec.Command(keaBinary, "-t", f.Name()).CombinedOutput(); err != nil {
+			t.Fatalf("kea-dhcp4 -t rejected rendered config: %v\n%s", err, combined)
+		}
+	}
+}
--- a/internal/models/dhcp.go
+++ b/internal/models/dhcp.go
@@ -0,0 +1,53 @@
+package models
+
+import "time"
+
+// DHCPSettings ist die node-lokale Singleton-Konfiguration des Kea-DHCPv4-
+// Servers (ob diese Node DHCP betreibt + globale Defaults).
+type DHCPSettings struct {
+	ID           int       `gorm:"column:id;primaryKey"   json:"id"`
+	Enabled      bool      `gorm:"column:enabled"         json:"enabled"`
+	DefaultLease int       `gorm:"column:default_lease"   json:"default_lease"`
+	MaxLease     int       `gorm:"column:max_lease"       json:"max_lease"`
+	DomainName   string    `gorm:"column:domain_name"     json:"domain_name"`
+	DNSServers   string    `gorm:"column:dns_servers"     json:"dns_servers"`
+	CreatedAt    time.Time `gorm:"column:created_at"      json:"created_at"`
+	UpdatedAt    time.Time `gorm:"column:updated_at"      json:"updated_at"`
+}
+
+func (DHCPSettings) TableName() string { return "dhcp_settings" }
+
+// DHCPSubnet ist ein vom DHCP-Server bedientes Subnetz (an ein Interface
+// per NAME gebunden — cluster-sicher, da interface_id node-lokal wäre).
+type DHCPSubnet struct {
+	ID            int64     `gorm:"column:id;primaryKey"      json:"id"`
+	Name          string    `gorm:"column:name"               json:"name"`
+	InterfaceName string    `gorm:"column:interface_name"     json:"interface_name"`
+	SubnetCIDR    string    `gorm:"column:subnet_cidr"        json:"subnet_cidr"`
+	PoolStart     string    `gorm:"column:pool_start"         json:"pool_start"`
+	PoolEnd       string    `gorm:"column:pool_end"           json:"pool_end"`
+	Gateway       string    `gorm:"column:gateway"            json:"gateway"`
+	DNSServers    string    `gorm:"column:dns_servers"        json:"dns_servers"`
+	LeaseTime     *int      `gorm:"column:lease_time"         json:"lease_time,omitempty"`
+	Active        bool      `gorm:"column:active"             json:"active"`
+	Description   string    `gorm:"column:description"        json:"description"`
+	CreatedAt     time.Time `gorm:"column:created_at"         json:"created_at"`
+	UpdatedAt     time.Time `gorm:"column:updated_at"         json:"updated_at"`
+}
+
+func (DHCPSubnet) TableName() string { return "dhcp_subnets" }
+
+// DHCPReservation ist eine statische MAC→IP-Zuordnung innerhalb eines Subnets.
+type DHCPReservation struct {
+	ID         int64     `gorm:"column:id;primaryKey"   json:"id"`
+	SubnetID   int64     `gorm:"column:subnet_id"       json:"subnet_id"`
+	Name       string    `gorm:"column:name"            json:"name"`
+	MACAddress string    `gorm:"column:mac_address"     json:"mac_address"`
+	IPAddress  string    `gorm:"column:ip_address"      json:"ip_address"`
+	Hostname   string    `gorm:"column:hostname"        json:"hostname"`
+	Active     bool      `gorm:"column:active"          json:"active"`
+	CreatedAt  time.Time `gorm:"column:created_at"      json:"created_at"`
+	UpdatedAt  time.Time `gorm:"column:updated_at"      json:"updated_at"`
+}
+
+func (DHCPReservation) TableName() string { return "dhcp_reservations" }
--- a/internal/services/dhcp/dhcp.go
+++ b/internal/services/dhcp/dhcp.go
@@ -0,0 +1,238 @@
+// Package dhcp provides CRUD against the dhcp_settings (singleton),
+// dhcp_subnets, and dhcp_reservations tables. The Kea config renderer
+// in internal/kea consumes these.
+package dhcp
+
+import (
+	"context"
+	"errors"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"git.netcell-it.de/projekte/edgeguard-native/internal/models"
+)
+
+var (
+	ErrSubnetNotFound      = errors.New("dhcp subnet not found")
+	ErrReservationNotFound = errors.New("dhcp reservation not found")
+)
+
+type Repo struct {
+	Pool *pgxpool.Pool
+}
+
+func New(pool *pgxpool.Pool) *Repo { return &Repo{Pool: pool} }
+
+// ── Settings (singleton id=1) ────────────────────────────────────────
+
+func (r *Repo) GetSettings(ctx context.Context) (*models.DHCPSettings, error) {
+	var s models.DHCPSettings
+	if err := r.Pool.QueryRow(ctx, `
+SELECT id, enabled, default_lease, max_lease, domain_name, dns_servers, created_at, updated_at
+FROM dhcp_settings WHERE id=1`).Scan(
+		&s.ID, &s.Enabled, &s.DefaultLease, &s.MaxLease, &s.DomainName, &s.DNSServers,
+		&s.CreatedAt, &s.UpdatedAt,
+	); err != nil {
+		return nil, err
+	}
+	return &s, nil
+}
+
+func (r *Repo) UpdateSettings(ctx context.Context, s models.DHCPSettings) (*models.DHCPSettings, error) {
+	row := r.Pool.QueryRow(ctx, `
+UPDATE dhcp_settings
+   SET enabled=$1, default_lease=$2, max_lease=$3, domain_name=$4, dns_servers=$5, updated_at=NOW()
+ WHERE id=1
+RETURNING id, enabled, default_lease, max_lease, domain_name, dns_servers, created_at, updated_at`,
+		s.Enabled, s.DefaultLease, s.MaxLease, s.DomainName, s.DNSServers)
+	var out models.DHCPSettings
+	if err := row.Scan(&out.ID, &out.Enabled, &out.DefaultLease, &out.MaxLease,
+		&out.DomainName, &out.DNSServers, &out.CreatedAt, &out.UpdatedAt); err != nil {
+		return nil, err
+	}
+	return &out, nil
+}
+
+// ── Subnets ──────────────────────────────────────────────────────────
+
+const subnetCols = `id, name, interface_name, subnet_cidr, pool_start, pool_end,
+       gateway, dns_servers, lease_time, active, description, created_at, updated_at`
+
+func scanSubnet(row pgx.Row) (*models.DHCPSubnet, error) {
+	var s models.DHCPSubnet
+	if err := row.Scan(&s.ID, &s.Name, &s.InterfaceName, &s.SubnetCIDR, &s.PoolStart,
+		&s.PoolEnd, &s.Gateway, &s.DNSServers, &s.LeaseTime, &s.Active, &s.Description,
+		&s.CreatedAt, &s.UpdatedAt); err != nil {
+		return nil, err
+	}
+	return &s, nil
+}
+
+func (r *Repo) ListSubnets(ctx context.Context) ([]models.DHCPSubnet, error) {
+	rows, err := r.Pool.Query(ctx, `SELECT `+subnetCols+` FROM dhcp_subnets ORDER BY name ASC`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := make([]models.DHCPSubnet, 0, 8)
+	for rows.Next() {
+		s, err := scanSubnet(rows)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, *s)
+	}
+	return out, rows.Err()
+}
+
+func (r *Repo) GetSubnet(ctx context.Context, id int64) (*models.DHCPSubnet, error) {
+	s, err := scanSubnet(r.Pool.QueryRow(ctx, `SELECT `+subnetCols+` FROM dhcp_subnets WHERE id=$1`, id))
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrSubnetNotFound
+		}
+		return nil, err
+	}
+	return s, nil
+}
+
+func (r *Repo) CreateSubnet(ctx context.Context, s models.DHCPSubnet) (*models.DHCPSubnet, error) {
+	return scanSubnet(r.Pool.QueryRow(ctx, `
+INSERT INTO dhcp_subnets (name, interface_name, subnet_cidr, pool_start, pool_end,
+       gateway, dns_servers, lease_time, active, description)
+VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10)
+RETURNING `+subnetCols,
+		s.Name, s.InterfaceName, s.SubnetCIDR, s.PoolStart, s.PoolEnd,
+		s.Gateway, s.DNSServers, s.LeaseTime, s.Active, s.Description))
+}
+
+func (r *Repo) UpdateSubnet(ctx context.Context, id int64, s models.DHCPSubnet) (*models.DHCPSubnet, error) {
+	out, err := scanSubnet(r.Pool.QueryRow(ctx, `
+UPDATE dhcp_subnets
+   SET name=$1, interface_name=$2, subnet_cidr=$3, pool_start=$4, pool_end=$5,
+       gateway=$6, dns_servers=$7, lease_time=$8, active=$9, description=$10, updated_at=NOW()
+ WHERE id=$11
+RETURNING `+subnetCols,
+		s.Name, s.InterfaceName, s.SubnetCIDR, s.PoolStart, s.PoolEnd,
+		s.Gateway, s.DNSServers, s.LeaseTime, s.Active, s.Description, id))
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrSubnetNotFound
+		}
+		return nil, err
+	}
+	return out, nil
+}
+
+func (r *Repo) DeleteSubnet(ctx context.Context, id int64) error {
+	tag, err := r.Pool.Exec(ctx, `DELETE FROM dhcp_subnets WHERE id=$1`, id)
+	if err != nil {
+		return err
+	}
+	if tag.RowsAffected() == 0 {
+		return ErrSubnetNotFound
+	}
+	return nil
+}
+
+// ── Reservations ─────────────────────────────────────────────────────
+
+const resvCols = `id, subnet_id, name, mac_address, ip_address, hostname, active, created_at, updated_at`
+
+func scanResv(row pgx.Row) (*models.DHCPReservation, error) {
+	var r models.DHCPReservation
+	if err := row.Scan(&r.ID, &r.SubnetID, &r.Name, &r.MACAddress, &r.IPAddress,
+		&r.Hostname, &r.Active, &r.CreatedAt, &r.UpdatedAt); err != nil {
+		return nil, err
+	}
+	return &r, nil
+}
+
+func (r *Repo) ListAllReservations(ctx context.Context) ([]models.DHCPReservation, error) {
+	rows, err := r.Pool.Query(ctx, `SELECT `+resvCols+` FROM dhcp_reservations ORDER BY subnet_id, ip_address`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := make([]models.DHCPReservation, 0, 16)
+	for rows.Next() {
+		v, err := scanResv(rows)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, *v)
+	}
+	return out, rows.Err()
+}
+
+func (r *Repo) ListReservationsForSubnet(ctx context.Context, subnetID int64) ([]models.DHCPReservation, error) {
+	rows, err := r.Pool.Query(ctx, `SELECT `+resvCols+` FROM dhcp_reservations WHERE subnet_id=$1 ORDER BY ip_address`, subnetID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := make([]models.DHCPReservation, 0, 8)
+	for rows.Next() {
+		v, err := scanResv(rows)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, *v)
+	}
+	return out, rows.Err()
+}
+
+func (r *Repo) GetReservation(ctx context.Context, id int64) (*models.DHCPReservation, error) {
+	v, err := scanResv(r.Pool.QueryRow(ctx, `SELECT `+resvCols+` FROM dhcp_reservations WHERE id=$1`, id))
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrReservationNotFound
+		}
+		return nil, err
+	}
+	return v, nil
+}
+
+func (r *Repo) CreateReservation(ctx context.Context, v models.DHCPReservation) (*models.DHCPReservation, error) {
+	return scanResv(r.Pool.QueryRow(ctx, `
+INSERT INTO dhcp_reservations (subnet_id, name, mac_address, ip_address, hostname, active)
+VALUES ($1,$2,$3,$4,$5,$6)
+RETURNING `+resvCols,
+		v.SubnetID, v.Name, v.MACAddress, v.IPAddress, v.Hostname, v.Active))
+}
+
+func (r *Repo) UpdateReservation(ctx context.Context, id int64, v models.DHCPReservation) (*models.DHCPReservation, error) {
+	out, err := scanResv(r.Pool.QueryRow(ctx, `
+UPDATE dhcp_reservations
+   SET name=$1, mac_address=$2, ip_address=$3, hostname=$4, active=$5, updated_at=NOW()
+ WHERE id=$6
+RETURNING `+resvCols,
+		v.Name, v.MACAddress, v.IPAddress, v.Hostname, v.Active, id))
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, ErrReservationNotFound
+		}
+		return nil, err
+	}
+	return out, nil
+}
+
+func (r *Repo) DeleteReservation(ctx context.Context, id int64) error {
+	tag, err := r.Pool.Exec(ctx, `DELETE FROM dhcp_reservations WHERE id=$1`, id)
+	if err != nil {
+		return err
+	}
+	if tag.RowsAffected() == 0 {
+		return ErrReservationNotFound
+	}
+	return nil
+}
+
+// InterfaceExists prüft, ob ein Interface-Name in network_interfaces existiert
+// (für die Validierung beim Anlegen/Ändern von Subnets).
+func (r *Repo) InterfaceExists(ctx context.Context, name string) (bool, error) {
+	var exists bool
+	err := r.Pool.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM network_interfaces WHERE name=$1)`, name).Scan(&exists)
+	return exists, err
+}
--- a/management-ui/src/App.tsx
+++ b/management-ui/src/App.tsx
@@ -27,6 +27,7 @@ const FirewallPage = lazy(() => import('./pages/Firewall'))
 const WireguardPage = lazy(() => import('./pages/Wireguard'))
 const ForwardProxyPage = lazy(() => import('./pages/ForwardProxy'))
 const DNSPage = lazy(() => import('./pages/DNS'))
+const DHCPPage = lazy(() => import('./pages/DHCP'))
 const NTPPage = lazy(() => import('./pages/NTP'))
 const ClusterPage = lazy(() => import('./pages/Cluster'))
 const FirewallLivePage = lazy(() => import('./pages/FirewallLive'))
@@ -161,6 +162,7 @@ export default function App() {
                <Route path="/vpn/wireguard" element={<WireguardPage />} />
                <Route path="/forward-proxy" element={<ForwardProxyPage />} />
                <Route path="/dns" element={<DNSPage />} />
+                <Route path="/dhcp" element={<DHCPPage />} />
                <Route path="/ntp" element={<NTPPage />} />
                  <Route path="/cluster" element={<ClusterPage />} />
                  <Route path="/logs" element={<LogsPage />} />
--- a/management-ui/src/components/Layout/AppLayout.tsx
+++ b/management-ui/src/components/Layout/AppLayout.tsx
@@ -19,6 +19,7 @@ const PAGE_TITLES: Record<string, string> = {
  '/ip-addresses':   'nav.ipAddresses',
  '/ssl':            'nav.ssl',
  '/dns':            'nav.dns',
+  '/dhcp':           'nav.dhcp',
  '/ntp':            'nav.ntp',
  '/vpn/wireguard':  'nav.wireguard',
  '/forward-proxy':  'nav.forwardProxy',
--- a/management-ui/src/components/Layout/Sidebar.tsx
+++ b/management-ui/src/components/Layout/Sidebar.tsx
@@ -67,6 +67,7 @@ const NAV: NavSection[] = [
      { path: '/ip-addresses', labelKey: 'nav.ipAddresses', icon: <NodeIndexOutlined /> },
      { path: '/ssl',          labelKey: 'nav.ssl',         icon: <SafetyCertificateOutlined /> },
      { path: '/dns',          labelKey: 'nav.dns',         icon: <GlobalOutlined /> },
+      { path: '/dhcp',         labelKey: 'nav.dhcp',        icon: <CloudServerOutlined /> },
      { path: '/ntp',          labelKey: 'nav.ntp',         icon: <ClockCircleOutlined /> },
    ],
  },
--- a/management-ui/src/i18n/locales/de/common.json
+++ b/management-ui/src/i18n/locales/de/common.json
@@ -15,6 +15,7 @@
    "wireguard": "WireGuard",
    "forwardProxy": "Forward-Proxy",
    "dns": "DNS",
+    "dhcp": "DHCP",
    "ntp": "Zeit (NTP)",
    "firewall": "Firewall",
    "firewallLive": "Firewall-Log",
@@ -1075,6 +1076,52 @@
      "failed": "Import fehlgeschlagen"
    }
  },
+  "dhcp": {
+    "title": "DHCP (Kea)",
+    "intro": "DHCPv4-Server: globale Optionen, pro-Subnet-Pools und statische Reservierungen.",
+    "csvHint": "Komma-getrennt.",
+    "saved": "Gespeichert",
+    "saveFailed": "Speichern fehlgeschlagen",
+    "deleted": "Gelöscht",
+    "deleteFailed": "Löschen fehlgeschlagen",
+    "reservations": "Reservierungen",
+    "haWarnTitle": "Nur auf EINER Node aktivieren",
+    "haWarnDesc": "Zwei DHCP-Server im selben LAN führen zu Adresskonflikten. Diese Einstellung ist node-lokal — aktiviere DHCP nur auf einer Cluster-Node.",
+    "tabs": {
+      "settings": "Einstellungen",
+      "subnets": "Subnets"
+    },
+    "settings": {
+      "enabled": "DHCP auf dieser Node aktiv",
+      "defaultLease": "Standard-Lease-Zeit (Sekunden)",
+      "maxLease": "Max-Lease-Zeit (Sekunden)",
+      "domainName": "Domain-Name",
+      "dnsServers": "DNS-Server (global)"
+    },
+    "subnet": {
+      "name": "Name",
+      "interface": "Interface",
+      "cidr": "Subnetz (CIDR)",
+      "pool": "Pool",
+      "poolStart": "Pool-Start",
+      "poolEnd": "Pool-Ende",
+      "gateway": "Gateway",
+      "dnsServers": "DNS-Server",
+      "active": "Aktiv",
+      "add": "Subnet hinzufügen",
+      "edit": "Subnet bearbeiten",
+      "deleteConfirm": "Subnet \"{{name}}\" wirklich löschen?"
+    },
+    "reservation": {
+      "name": "Name",
+      "mac": "MAC-Adresse",
+      "ip": "IP-Adresse",
+      "hostname": "Hostname",
+      "add": "Reservierung hinzufügen",
+      "edit": "Reservierung bearbeiten",
+      "deleteConfirm": "Reservierung wirklich löschen?"
+    }
+  },
  "ntp": {
    "title": "Zeitserver (Chrony)",
    "intro": "Chrony als Time-Sync-Daemon (NTP). Quellen oben, Listen-/Serve-Konfig im Settings-Tab. Wenn 'serve_clients' aktiv und LAN-IPs gebound sind, wird die Box selbst zum NTP-Server für das LAN.",
--- a/management-ui/src/i18n/locales/en/common.json
+++ b/management-ui/src/i18n/locales/en/common.json
@@ -15,6 +15,7 @@
    "wireguard": "WireGuard",
    "forwardProxy": "Forward proxy",
    "dns": "DNS",
+    "dhcp": "DHCP",
    "ntp": "Time (NTP)",
    "firewall": "Firewall",
    "firewallLive": "Firewall log",
@@ -1075,6 +1076,52 @@
      "failed": "Import failed"
    }
  },
+  "dhcp": {
+    "title": "DHCP (Kea)",
+    "intro": "DHCPv4 server: global options, per-subnet pools and static reservations.",
+    "csvHint": "Comma-separated.",
+    "saved": "Saved",
+    "saveFailed": "Save failed",
+    "deleted": "Deleted",
+    "deleteFailed": "Delete failed",
+    "reservations": "Reservations",
+    "haWarnTitle": "Enable on ONE node only",
+    "haWarnDesc": "Two DHCP servers on the same LAN cause address conflicts. This setting is node-local — enable DHCP on a single cluster node only.",
+    "tabs": {
+      "settings": "Settings",
+      "subnets": "Subnets"
+    },
+    "settings": {
+      "enabled": "DHCP active on this node",
+      "defaultLease": "Default lease time (seconds)",
+      "maxLease": "Max lease time (seconds)",
+      "domainName": "Domain name",
+      "dnsServers": "DNS servers (global)"
+    },
+    "subnet": {
+      "name": "Name",
+      "interface": "Interface",
+      "cidr": "Subnet (CIDR)",
+      "pool": "Pool",
+      "poolStart": "Pool start",
+      "poolEnd": "Pool end",
+      "gateway": "Gateway",
+      "dnsServers": "DNS servers",
+      "active": "Active",
+      "add": "Add subnet",
+      "edit": "Edit subnet",
+      "deleteConfirm": "Really delete subnet \"{{name}}\"?"
+    },
+    "reservation": {
+      "name": "Name",
+      "mac": "MAC address",
+      "ip": "IP address",
+      "hostname": "Hostname",
+      "add": "Add reservation",
+      "edit": "Edit reservation",
+      "deleteConfirm": "Really delete this reservation?"
+    }
+  },
  "ntp": {
    "title": "Time server (Chrony)",
    "intro": "Chrony as time-sync daemon (NTP). Sources on top, listen/serve config on the settings tab. With 'serve_clients' on and LAN-IPs bound, the box itself becomes an NTP server for the LAN.",
--- a/management-ui/src/pages/DHCP/index.tsx
+++ b/management-ui/src/pages/DHCP/index.tsx
@@ -0,0 +1,385 @@
+import { useEffect, useState } from 'react'
+import {
+  Alert, Button, Card, Form, Input, InputNumber, Modal, Popconfirm, Space,
+  Switch, Table, Tabs, Tag, Tooltip, Typography, message, Select,
+} from 'antd'
+import type { ColumnsType } from 'antd/es/table'
+import { CloudServerOutlined, PlusOutlined } from '@ant-design/icons'
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
+import { useTranslation } from 'react-i18next'
+
+import apiClient, { isEnvelope } from '../../api/client'
+import { useAuthStore } from '../../stores/auth'
+import PageHeader from '../../components/PageHeader'
+
+const { Text } = Typography
+
+interface DHCPSettings {
+  id: number
+  enabled: boolean
+  default_lease: number
+  max_lease: number
+  domain_name: string
+  dns_servers: string
+}
+interface DHCPSubnet {
+  id: number
+  name: string
+  interface_name: string
+  subnet_cidr: string
+  pool_start: string
+  pool_end: string
+  gateway: string
+  dns_servers: string
+  lease_time?: number | null
+  active: boolean
+  description: string
+}
+interface DHCPReservation {
+  id: number
+  subnet_id: number
+  name: string
+  mac_address: string
+  ip_address: string
+  hostname: string
+  active: boolean
+}
+interface NetIface { name: string; role: string }
+
+export default function DHCPPage() {
+  const { t } = useTranslation()
+  return (
+    <div>
+      <PageHeader icon={<CloudServerOutlined />} title={t('dhcp.title')} subtitle={t('dhcp.intro')} />
+      <Tabs
+        defaultActiveKey="settings"
+        items={[
+          { key: 'settings', label: t('dhcp.tabs.settings'), children: <SettingsTab /> },
+          { key: 'subnets', label: t('dhcp.tabs.subnets'), children: <SubnetsTab /> },
+        ]}
+      />
+    </div>
+  )
+}
+
+// ── Settings ─────────────────────────────────────────────────────────
+
+function SettingsTab() {
+  const { t } = useTranslation()
+  const qc = useQueryClient()
+  const isViewer = useAuthStore((s) => s.user?.role) === 'viewer'
+  const [msg, msgCtx] = message.useMessage()
+  const [form] = Form.useForm<DHCPSettings>()
+
+  const { data } = useQuery({
+    queryKey: ['dhcp', 'settings'],
+    queryFn: async () => {
+      const r = await apiClient.get('/dhcp/settings')
+      return isEnvelope(r.data) ? (r.data.data as DHCPSettings) : null
+    },
+  })
+  useEffect(() => { if (data) form.setFieldsValue(data) }, [data, form])
+
+  const save = useMutation({
+    mutationFn: async (v: DHCPSettings) => apiClient.put('/dhcp/settings', v),
+    onSuccess: () => {
+      msg.success(t('dhcp.saved'))
+      void qc.invalidateQueries({ queryKey: ['dhcp', 'settings'] })
+    },
+    onError: (e: Error) => msg.error(t('dhcp.saveFailed') + ': ' + e.message),
+  })
+
+  return (
+    <Card size="small">
+      {msgCtx}
+      <Alert
+        type="warning"
+        showIcon
+        className="mb-16"
+        message={t('dhcp.haWarnTitle')}
+        description={t('dhcp.haWarnDesc')}
+      />
+      <Form<DHCPSettings> form={form} layout="vertical" onFinish={(v) => save.mutate(v)}>
+        <Form.Item label={t('dhcp.settings.enabled')} name="enabled" valuePropName="checked">
+          <Switch disabled={isViewer} />
+        </Form.Item>
+        <Form.Item label={t('dhcp.settings.defaultLease')} name="default_lease">
+          <InputNumber min={60} style={{ width: 240 }} disabled={isViewer} />
+        </Form.Item>
+        <Form.Item label={t('dhcp.settings.maxLease')} name="max_lease">
+          <InputNumber min={60} style={{ width: 240 }} disabled={isViewer} />
+        </Form.Item>
+        <Form.Item label={t('dhcp.settings.domainName')} name="domain_name">
+          <Input placeholder="lan" disabled={isViewer} />
+        </Form.Item>
+        <Form.Item label={t('dhcp.settings.dnsServers')} name="dns_servers" extra={t('dhcp.csvHint')}>
+          <Input placeholder="1.1.1.1, 8.8.8.8" disabled={isViewer} />
+        </Form.Item>
+        <Form.Item style={{ marginBottom: 0 }}>
+          <Tooltip title={isViewer ? t('auth.viewerBadge') : undefined}>
+            <Button type="primary" htmlType="submit" loading={save.isPending} disabled={isViewer}>
+              {t('common.save')}
+            </Button>
+          </Tooltip>
+        </Form.Item>
+      </Form>
+    </Card>
+  )
+}
+
+// ── Subnets ──────────────────────────────────────────────────────────
+
+function SubnetsTab() {
+  const { t } = useTranslation()
+  const qc = useQueryClient()
+  const isViewer = useAuthStore((s) => s.user?.role) === 'viewer'
+  const [msg, msgCtx] = message.useMessage()
+  const [form] = Form.useForm<DHCPSubnet>()
+  const [editing, setEditing] = useState<DHCPSubnet | null>(null)
+  const [open, setOpen] = useState(false)
+  const [resvFor, setResvFor] = useState<DHCPSubnet | null>(null)
+
+  const { data: subnets } = useQuery({
+    queryKey: ['dhcp', 'subnets'],
+    queryFn: async () => {
+      const r = await apiClient.get('/dhcp/subnets')
+      return isEnvelope(r.data) ? ((r.data.data as { subnets?: DHCPSubnet[] }).subnets ?? []) : []
+    },
+  })
+  const { data: ifaces } = useQuery({
+    queryKey: ['network-interfaces'],
+    queryFn: async () => {
+      const r = await apiClient.get('/network-interfaces')
+      return isEnvelope(r.data) ? ((r.data.data as { interfaces?: NetIface[] }).interfaces ?? []) : []
+    },
+  })
+
+  const save = useMutation({
+    mutationFn: async (v: DHCPSubnet) => {
+      if (editing) return apiClient.put(`/dhcp/subnets/${editing.id}`, v)
+      return apiClient.post('/dhcp/subnets', v)
+    },
+    onSuccess: () => {
+      msg.success(t('dhcp.saved'))
+      setOpen(false); setEditing(null)
+      void qc.invalidateQueries({ queryKey: ['dhcp', 'subnets'] })
+    },
+    onError: (e: Error) => msg.error(t('dhcp.saveFailed') + ': ' + e.message),
+  })
+  const del = useMutation({
+    mutationFn: async (id: number) => apiClient.delete(`/dhcp/subnets/${id}`),
+    onSuccess: () => {
+      msg.success(t('dhcp.deleted'))
+      void qc.invalidateQueries({ queryKey: ['dhcp', 'subnets'] })
+    },
+    onError: (e: Error) => msg.error(t('dhcp.deleteFailed') + ': ' + e.message),
+  })
+
+  const openNew = () => {
+    setEditing(null)
+    form.resetFields()
+    form.setFieldsValue({ active: true } as Partial<DHCPSubnet>)
+    setOpen(true)
+  }
+  const openEdit = (s: DHCPSubnet) => {
+    setEditing(s)
+    form.setFieldsValue(s)
+    setOpen(true)
+  }
+
+  const cols: ColumnsType<DHCPSubnet> = [
+    { title: t('dhcp.subnet.name'), dataIndex: 'name' },
+    { title: t('dhcp.subnet.interface'), dataIndex: 'interface_name' },
+    { title: t('dhcp.subnet.cidr'), dataIndex: 'subnet_cidr' },
+    {
+      title: t('dhcp.subnet.pool'), key: 'pool',
+      render: (_, r) => (r.pool_start && r.pool_end ? `${r.pool_start} – ${r.pool_end}` : '—'),
+    },
+    { title: t('dhcp.subnet.gateway'), dataIndex: 'gateway', render: (v) => v || '—' },
+    {
+      title: t('common.status'), dataIndex: 'active',
+      render: (v: boolean) => <Tag color={v ? 'green' : 'default'}>{v ? t('common.active') : t('common.inactive')}</Tag>,
+    },
+    {
+      title: t('common.actions'), key: 'actions', width: 280,
+      render: (_, r) => (
+        <Space>
+          <Button size="small" onClick={() => setResvFor(r)}>{t('dhcp.reservations')}</Button>
+          {!isViewer && <Button size="small" onClick={() => openEdit(r)}>{t('common.edit')}</Button>}
+          {!isViewer && (
+            <Popconfirm title={t('dhcp.subnet.deleteConfirm', { name: r.name })} onConfirm={() => del.mutate(r.id)}>
+              <Button size="small" danger>{t('common.delete')}</Button>
+            </Popconfirm>
+          )}
+        </Space>
+      ),
+    },
+  ]
+
+  return (
+    <Card size="small">
+      {msgCtx}
+      <Space style={{ marginBottom: 12 }}>
+        <Button type="primary" icon={<PlusOutlined />} onClick={openNew} disabled={isViewer}>
+          {t('dhcp.subnet.add')}
+        </Button>
+      </Space>
+      <Table<DHCPSubnet> rowKey="id" size="small" columns={cols} dataSource={subnets ?? []} pagination={false} />
+
+      <Modal
+        title={editing ? t('dhcp.subnet.edit') : t('dhcp.subnet.add')}
+        open={open}
+        onCancel={() => setOpen(false)}
+        onOk={() => form.submit()}
+        confirmLoading={save.isPending}
+        destroyOnClose
+      >
+        <Form<DHCPSubnet> form={form} layout="vertical" onFinish={(v) => save.mutate(v)}>
+          <Form.Item label={t('dhcp.subnet.name')} name="name" rules={[{ required: true }]}>
+            <Input />
+          </Form.Item>
+          <Form.Item label={t('dhcp.subnet.interface')} name="interface_name" rules={[{ required: true }]}>
+            <Select
+              options={(ifaces ?? []).map((i) => ({ value: i.name, label: `${i.name} (${i.role})` }))}
+              showSearch
+            />
+          </Form.Item>
+          <Form.Item label={t('dhcp.subnet.cidr')} name="subnet_cidr" rules={[{ required: true }]}>
+            <Input placeholder="10.0.0.0/24" />
+          </Form.Item>
+          <Space>
+            <Form.Item label={t('dhcp.subnet.poolStart')} name="pool_start">
+              <Input placeholder="10.0.0.100" />
+            </Form.Item>
+            <Form.Item label={t('dhcp.subnet.poolEnd')} name="pool_end">
+              <Input placeholder="10.0.0.200" />
+            </Form.Item>
+          </Space>
+          <Form.Item label={t('dhcp.subnet.gateway')} name="gateway">
+            <Input placeholder="10.0.0.1" />
+          </Form.Item>
+          <Form.Item label={t('dhcp.subnet.dnsServers')} name="dns_servers" extra={t('dhcp.csvHint')}>
+            <Input placeholder="1.1.1.1, 8.8.8.8" />
+          </Form.Item>
+          <Form.Item label={t('dhcp.subnet.active')} name="active" valuePropName="checked">
+            <Switch />
+          </Form.Item>
+        </Form>
+      </Modal>
+
+      {resvFor && (
+        <ReservationsModal subnet={resvFor} onClose={() => setResvFor(null)} />
+      )}
+    </Card>
+  )
+}
+
+// ── Reservations (per subnet) ────────────────────────────────────────
+
+function ReservationsModal({ subnet, onClose }: { subnet: DHCPSubnet; onClose: () => void }) {
+  const { t } = useTranslation()
+  const qc = useQueryClient()
+  const isViewer = useAuthStore((s) => s.user?.role) === 'viewer'
+  const [msg, msgCtx] = message.useMessage()
+  const [form] = Form.useForm<DHCPReservation>()
+  const [editing, setEditing] = useState<DHCPReservation | null>(null)
+  const [formOpen, setFormOpen] = useState(false)
+
+  const key = ['dhcp', 'reservations', subnet.id]
+  const { data } = useQuery({
+    queryKey: key,
+    queryFn: async () => {
+      const r = await apiClient.get(`/dhcp/subnets/${subnet.id}/reservations`)
+      return isEnvelope(r.data) ? ((r.data.data as { reservations?: DHCPReservation[] }).reservations ?? []) : []
+    },
+  })
+
+  const save = useMutation({
+    mutationFn: async (v: DHCPReservation) => {
+      if (editing) return apiClient.put(`/dhcp/reservations/${editing.id}`, v)
+      return apiClient.post(`/dhcp/subnets/${subnet.id}/reservations`, v)
+    },
+    onSuccess: () => {
+      msg.success(t('dhcp.saved'))
+      setFormOpen(false); setEditing(null)
+      void qc.invalidateQueries({ queryKey: key })
+    },
+    onError: (e: Error) => msg.error(t('dhcp.saveFailed') + ': ' + e.message),
+  })
+  const del = useMutation({
+    mutationFn: async (id: number) => apiClient.delete(`/dhcp/reservations/${id}`),
+    onSuccess: () => {
+      msg.success(t('dhcp.deleted'))
+      void qc.invalidateQueries({ queryKey: key })
+    },
+    onError: (e: Error) => msg.error(t('dhcp.deleteFailed') + ': ' + e.message),
+  })
+
+  const cols: ColumnsType<DHCPReservation> = [
+    { title: t('dhcp.reservation.mac'), dataIndex: 'mac_address' },
+    { title: t('dhcp.reservation.ip'), dataIndex: 'ip_address' },
+    { title: t('dhcp.reservation.hostname'), dataIndex: 'hostname', render: (v) => v || '—' },
+    {
+      title: t('common.actions'), key: 'actions', width: 180,
+      render: (_, r) => (
+        <Space>
+          {!isViewer && <Button size="small" onClick={() => { setEditing(r); form.setFieldsValue(r); setFormOpen(true) }}>{t('common.edit')}</Button>}
+          {!isViewer && (
+            <Popconfirm title={t('dhcp.reservation.deleteConfirm')} onConfirm={() => del.mutate(r.id)}>
+              <Button size="small" danger>{t('common.delete')}</Button>
+            </Popconfirm>
+          )}
+        </Space>
+      ),
+    },
+  ]
+
+  return (
+    <Modal
+      title={`${t('dhcp.reservations')} — ${subnet.name}`}
+      open
+      onCancel={onClose}
+      footer={null}
+      width={640}
+    >
+      {msgCtx}
+      <Space style={{ marginBottom: 12 }}>
+        <Button
+          type="primary" icon={<PlusOutlined />} disabled={isViewer}
+          onClick={() => { setEditing(null); form.resetFields(); form.setFieldsValue({ active: true } as Partial<DHCPReservation>); setFormOpen(true) }}
+        >
+          {t('dhcp.reservation.add')}
+        </Button>
+      </Space>
+      <Table<DHCPReservation> rowKey="id" size="small" columns={cols} dataSource={data ?? []} pagination={false} />
+
+      <Modal
+        title={editing ? t('dhcp.reservation.edit') : t('dhcp.reservation.add')}
+        open={formOpen}
+        onCancel={() => setFormOpen(false)}
+        onOk={() => form.submit()}
+        confirmLoading={save.isPending}
+        destroyOnClose
+      >
+        <Form<DHCPReservation> form={form} layout="vertical" onFinish={(v) => save.mutate(v)}>
+          <Form.Item label={t('dhcp.reservation.name')} name="name">
+            <Input />
+          </Form.Item>
+          <Form.Item label={t('dhcp.reservation.mac')} name="mac_address" rules={[{ required: true }]}>
+            <Input placeholder="aa:bb:cc:dd:ee:ff" />
+          </Form.Item>
+          <Form.Item label={t('dhcp.reservation.ip')} name="ip_address" rules={[{ required: true }]}>
+            <Input placeholder="10.0.0.50" />
+          </Form.Item>
+          <Form.Item label={t('dhcp.reservation.hostname')} name="hostname">
+            <Input />
+          </Form.Item>
+          <Form.Item label={t('dhcp.subnet.active')} name="active" valuePropName="checked">
+            <Switch />
+          </Form.Item>
+        </Form>
+      </Modal>
+      <Text type="secondary" style={{ fontSize: 12 }}>{subnet.subnet_cidr}</Text>
+    </Modal>
+  )
+}
--- a/packaging/debian/edgeguard-api/DEBIAN/control
+++ b/packaging/debian/edgeguard-api/DEBIAN/control
@@ -12,7 +12,7 @@ Description: EdgeGuard — native Reverse-Proxy / LB / Forward-Proxy / VPN / Fir
 PG Streaming Replication + provider Floating-IP for HTTP ingress).
 .
 This package ships the management API, scheduler and CLI.
-Depends: postgresql-16 | postgresql-17, haproxy (>= 2.8), squid, wireguard-tools, unbound, chrony, nftables, keepalived, certbot, openssl, sudo, adduser, systemd, ca-certificates, ulogd2, ulogd2-json, iputils-ping, traceroute, dnsutils, curl, netcat-openbsd
+Depends: postgresql-16 | postgresql-17, haproxy (>= 2.8), squid, wireguard-tools, unbound, chrony, kea-dhcp4-server, nftables, keepalived, certbot, openssl, sudo, adduser, systemd, ca-certificates, ulogd2, ulogd2-json, iputils-ping, traceroute, dnsutils, curl, netcat-openbsd
 Recommends: edgeguard-keydb (>= 6.3.4-edgeguard1), apparmor, fail2ban
 Section: admin
 Priority: optional
--- a/packaging/debian/edgeguard-api/DEBIAN/postinst
+++ b/packaging/debian/edgeguard-api/DEBIAN/postinst
@@ -48,6 +48,7 @@ case "$1" in
        # gespeichert, alles sind Renderer-Outputs.
        for d in /etc/edgeguard /etc/edgeguard/haproxy /etc/edgeguard/squid \
                 /etc/edgeguard/wireguard /etc/edgeguard/unbound \
+                 /etc/edgeguard/kea \
                 /etc/edgeguard/nftables.d; do
            install -d -m 0755 -o "$EG_USER" -g "$EG_USER" "$d"
        done
@@ -118,6 +119,15 @@ edgeguard ALL=(root) NOPASSWD: /usr/bin/systemctl reload chrony.service
 edgeguard ALL=(root) NOPASSWD: /bin/systemctl reload chrony.service
 edgeguard ALL=(root) NOPASSWD: /usr/bin/systemctl restart chrony.service
 edgeguard ALL=(root) NOPASSWD: /bin/systemctl restart chrony.service
+# DHCP (Kea): Service-Lifecycle an dhcp_settings.enabled gekoppelt.
+edgeguard ALL=(root) NOPASSWD: /usr/bin/systemctl restart kea-dhcp4-server.service
+edgeguard ALL=(root) NOPASSWD: /bin/systemctl restart kea-dhcp4-server.service
+edgeguard ALL=(root) NOPASSWD: /usr/bin/systemctl stop kea-dhcp4-server.service
+edgeguard ALL=(root) NOPASSWD: /bin/systemctl stop kea-dhcp4-server.service
+edgeguard ALL=(root) NOPASSWD: /usr/bin/systemctl enable kea-dhcp4-server.service
+edgeguard ALL=(root) NOPASSWD: /bin/systemctl enable kea-dhcp4-server.service
+edgeguard ALL=(root) NOPASSWD: /usr/bin/systemctl disable kea-dhcp4-server.service
+edgeguard ALL=(root) NOPASSWD: /bin/systemctl disable kea-dhcp4-server.service
 edgeguard ALL=(root) NOPASSWD: /usr/bin/apt-get update -qq
 edgeguard ALL=(root) NOPASSWD: /usr/bin/apt-get update
 # Auto-Update-Toggle (Settings → Automatische Updates) schreibt/entfernt
@@ -228,6 +238,19 @@ SUDOERS
        fi
        chown "$EG_USER":"$EG_USER" /etc/chrony/conf.d/edgeguard.conf
        chmod 0644 /etc/chrony/conf.d/edgeguard.conf
+
+        # Kea DHCPv4: managed config unter /etc/edgeguard/kea, vom Distro-
+        # Pfad symlinked (Distro-Original wird gesichert). Der Dienst läuft
+        # NUR, wenn der Operator DHCP aktiviert (Default AUS) — kein
+        # rogue DHCP-Server nach Install. Der Renderer enabled+restartet
+        # kea-dhcp4-server, sobald dhcp_settings.enabled=true gesetzt wird.
+        install -d /etc/kea
+        if [ -f /etc/kea/kea-dhcp4.conf ] && [ ! -L /etc/kea/kea-dhcp4.conf ]; then
+            mv /etc/kea/kea-dhcp4.conf /etc/kea/kea-dhcp4.conf.distro-bak
+        fi
+        ln -sfn /etc/edgeguard/kea/kea-dhcp4.conf /etc/kea/kea-dhcp4.conf
+        systemctl disable --now kea-dhcp4-server.service 2>/dev/null || true
+
        chmod 0440 /etc/sudoers.d/edgeguard

        # ── Sysctl-Profil für Edge-Gateway (NAT + HAProxy + Forwarding) ──
@@ -1 +1 @@
 .2.91
 .2.92