Add DNS filtering with dnsmasq address=/ directives for wildcard blocking

Adds Pi-hole-style DNS filtering using dnsmasq's native address=/ directives,
which block domains and all subdomains. Users subscribe to blocklists by URL
or upload files, with suggested lists from Hagezi, Steven Black, and OISD.
Background runner refreshes lists on a configurable interval (default 24h).

internal/api/v1/handlers_dnsfilter.go

@@ -0,0 +1,351 @@
+package v1
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+
+	"github.com/gorilla/mux"
+	"github.com/wild-cloud/wild-central/internal/config"
+	"github.com/wild-cloud/wild-central/internal/dnsfilter"
+)
+
+// DNSFilterStatus returns the current DNS filter status and stats.
+func (api *API) DNSFilterStatus(w http.ResponseWriter, r *http.Request) {
+	state, err := config.LoadState(api.statePath())
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "Failed to load state")
+		return
+	}
+
+	stats := api.dnsFilter.GetStats()
+	stats.Enabled = state.Cloud.DNSFilter.Enabled
+
+	if stats.Enabled {
+		stats.QueryStats = api.dnsFilter.GetQueryStats()
+	}
+
+	respondJSON(w, http.StatusOK, stats)
+}
+
+// DNSFilterGetConfig returns the DNS filter configuration from state.yaml.
+func (api *API) DNSFilterGetConfig(w http.ResponseWriter, r *http.Request) {
+	state, err := config.LoadState(api.statePath())
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "Failed to load state")
+		return
+	}
+
+	respondJSON(w, http.StatusOK, state.Cloud.DNSFilter)
+}
+
+// DNSFilterUpdateConfig enables/disables DNS filtering and updates settings.
+func (api *API) DNSFilterUpdateConfig(w http.ResponseWriter, r *http.Request) {
+	var req struct {
+		Enabled       *bool `json:"enabled"`
+		IntervalHours *int  `json:"intervalHours"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		respondError(w, http.StatusBadRequest, "Invalid request body")
+		return
+	}
+
+	state, err := config.LoadState(api.statePath())
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "Failed to load state")
+		return
+	}
+
+	if req.Enabled != nil {
+		state.Cloud.DNSFilter.Enabled = *req.Enabled
+	}
+	if req.IntervalHours != nil {
+		state.Cloud.DNSFilter.IntervalHours = *req.IntervalHours
+	}
+
+	if err := config.SaveState(state, api.statePath()); err != nil {
+		respondError(w, http.StatusInternalServerError, "Failed to save state")
+		return
+	}
+
+	if state.Cloud.DNSFilter.Enabled {
+		if err := api.dnsFilter.EnsureDataDir(); err != nil {
+			respondError(w, http.StatusInternalServerError, fmt.Sprintf("Failed to create data dir: %v", err))
+			return
+		}
+
+		// Start or restart the runner
+		interval := state.Cloud.DNSFilter.IntervalHours
+		if interval <= 0 {
+			interval = 24
+		}
+		api.dnsFilterRunner.Start(api.ctx, interval)
+
+		slog.Info("dns-filter: enabled", "interval", interval)
+	} else {
+		// Stop the runner and clear addn-hosts
+		api.dnsFilterRunner.Stop()
+		api.dnsmasq.SetFilterConfPath("")
+
+		slog.Info("dns-filter: disabled")
+	}
+
+	// Reconcile to add/remove addn-hosts from dnsmasq config
+	go api.reconcileNetworking()
+
+	api.broadcastDNSFilterEvent("dns-filter:config", "DNS filter configuration updated")
+	respondMessage(w, http.StatusOK, "DNS filter configuration updated")
+}
+
+// DNSFilterGetLists returns all subscribed blocklists.
+func (api *API) DNSFilterGetLists(w http.ResponseWriter, r *http.Request) {
+	fd, err := api.dnsFilter.LoadFilterData()
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "Failed to load filter data")
+		return
+	}
+
+	respondJSON(w, http.StatusOK, map[string]any{
+		"lists": fd.Lists,
+	})
+}
+
+// DNSFilterAddList adds a URL-based blocklist subscription.
+func (api *API) DNSFilterAddList(w http.ResponseWriter, r *http.Request) {
+	var req struct {
+		URL  string `json:"url"`
+		Name string `json:"name"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		respondError(w, http.StatusBadRequest, "Invalid request body")
+		return
+	}
+
+	if req.URL == "" || req.Name == "" {
+		respondError(w, http.StatusBadRequest, "URL and name are required")
+		return
+	}
+
+	bl := dnsfilter.Blocklist{
+		URL:  req.URL,
+		Name: req.Name,
+	}
+	if err := api.dnsFilter.AddList(bl); err != nil {
+		respondError(w, http.StatusConflict, err.Error())
+		return
+	}
+
+	// Trigger update if runner is active
+	if api.dnsFilterRunner.IsRunning() {
+		api.dnsFilterRunner.Trigger()
+	}
+
+	api.broadcastDNSFilterEvent("dns-filter:list-added", fmt.Sprintf("Added list: %s", req.Name))
+	respondMessage(w, http.StatusCreated, "List added")
+}
+
+// DNSFilterRemoveList removes a blocklist by ID.
+func (api *API) DNSFilterRemoveList(w http.ResponseWriter, r *http.Request) {
+	id := mux.Vars(r)["id"]
+	if id == "" {
+		respondError(w, http.StatusBadRequest, "List ID is required")
+		return
+	}
+
+	if err := api.dnsFilter.RemoveList(id); err != nil {
+		respondError(w, http.StatusNotFound, err.Error())
+		return
+	}
+
+	// Recompile without the removed list
+	go func() {
+		if _, err := api.dnsFilter.Compile(); err != nil {
+			slog.Warn("dns-filter: recompile after removal failed", "error", err)
+			return
+		}
+		if err := api.dnsmasq.ReloadService(); err != nil {
+			slog.Warn("dns-filter: reload after removal failed", "error", err)
+		}
+		api.broadcastDNSFilterEvent("dns-filter:updated", "DNS filter lists updated")
+	}()
+
+	respondMessage(w, http.StatusOK, "List removed")
+}
+
+// DNSFilterToggleList enables or disables a list.
+func (api *API) DNSFilterToggleList(w http.ResponseWriter, r *http.Request) {
+	id := mux.Vars(r)["id"]
+
+	var req struct {
+		Enabled bool `json:"enabled"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		respondError(w, http.StatusBadRequest, "Invalid request body")
+		return
+	}
+
+	if err := api.dnsFilter.ToggleList(id, req.Enabled); err != nil {
+		respondError(w, http.StatusNotFound, err.Error())
+		return
+	}
+
+	// Recompile with updated list status
+	go func() {
+		if _, err := api.dnsFilter.Compile(); err != nil {
+			slog.Warn("dns-filter: recompile after toggle failed", "error", err)
+			return
+		}
+		if err := api.dnsmasq.ReloadService(); err != nil {
+			slog.Warn("dns-filter: reload after toggle failed", "error", err)
+		}
+		api.broadcastDNSFilterEvent("dns-filter:updated", "DNS filter lists updated")
+	}()
+
+	respondMessage(w, http.StatusOK, "List toggled")
+}
+
+// DNSFilterGetCustomEntries returns all custom allow/block entries.
+func (api *API) DNSFilterGetCustomEntries(w http.ResponseWriter, r *http.Request) {
+	fd, err := api.dnsFilter.LoadFilterData()
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "Failed to load filter data")
+		return
+	}
+
+	respondJSON(w, http.StatusOK, map[string]any{
+		"customEntries": fd.CustomEntries,
+	})
+}
+
+// DNSFilterSetCustomEntry adds or updates a custom allow/block entry.
+func (api *API) DNSFilterSetCustomEntry(w http.ResponseWriter, r *http.Request) {
+	var req dnsfilter.CustomEntry
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		respondError(w, http.StatusBadRequest, "Invalid request body")
+		return
+	}
+
+	if req.Domain == "" {
+		respondError(w, http.StatusBadRequest, "Domain is required")
+		return
+	}
+
+	if err := api.dnsFilter.SetCustomEntry(req); err != nil {
+		respondError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	// Recompile with updated custom entries
+	go func() {
+		if _, err := api.dnsFilter.Compile(); err != nil {
+			slog.Warn("dns-filter: recompile after custom entry failed", "error", err)
+			return
+		}
+		if err := api.dnsmasq.ReloadService(); err != nil {
+			slog.Warn("dns-filter: reload after custom entry failed", "error", err)
+		}
+		api.broadcastDNSFilterEvent("dns-filter:updated", "DNS filter custom entry updated")
+	}()
+
+	respondMessage(w, http.StatusOK, "Custom entry saved")
+}
+
+// DNSFilterRemoveCustomEntry removes a custom entry by domain.
+func (api *API) DNSFilterRemoveCustomEntry(w http.ResponseWriter, r *http.Request) {
+	domain := mux.Vars(r)["domain"]
+	if domain == "" {
+		respondError(w, http.StatusBadRequest, "Domain is required")
+		return
+	}
+
+	if err := api.dnsFilter.RemoveCustomEntry(domain); err != nil {
+		respondError(w, http.StatusNotFound, err.Error())
+		return
+	}
+
+	// Recompile
+	go func() {
+		if _, err := api.dnsFilter.Compile(); err != nil {
+			slog.Warn("dns-filter: recompile after custom removal failed", "error", err)
+			return
+		}
+		if err := api.dnsmasq.ReloadService(); err != nil {
+			slog.Warn("dns-filter: reload after custom removal failed", "error", err)
+		}
+		api.broadcastDNSFilterEvent("dns-filter:updated", "DNS filter custom entry removed")
+	}()
+
+	respondMessage(w, http.StatusOK, "Custom entry removed")
+}
+
+// DNSFilterTriggerUpdate triggers an immediate list update.
+func (api *API) DNSFilterTriggerUpdate(w http.ResponseWriter, r *http.Request) {
+	if !api.dnsFilterRunner.IsRunning() {
+		respondError(w, http.StatusBadRequest, "DNS filter is not enabled")
+		return
+	}
+
+	api.dnsFilterRunner.Trigger()
+	respondJSON(w, http.StatusAccepted, map[string]string{
+		"message": "Update triggered",
+	})
+}
+
+// DNSFilterUploadList handles file upload for a blocklist.
+func (api *API) DNSFilterUploadList(w http.ResponseWriter, r *http.Request) {
+	if err := r.ParseMultipartForm(50 << 20); err != nil { // 50MB limit
+		respondError(w, http.StatusBadRequest, "Failed to parse upload")
+		return
+	}
+
+	name := r.FormValue("name")
+	if name == "" {
+		respondError(w, http.StatusBadRequest, "Name is required")
+		return
+	}
+
+	file, _, err := r.FormFile("file")
+	if err != nil {
+		respondError(w, http.StatusBadRequest, "File is required")
+		return
+	}
+	defer file.Close()
+
+	content, err := io.ReadAll(io.LimitReader(file, 50<<20))
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "Failed to read file")
+		return
+	}
+
+	id, err := api.dnsFilter.AddUploadedList(name, content)
+	if err != nil {
+		respondError(w, http.StatusConflict, err.Error())
+		return
+	}
+
+	// Recompile with new list
+	go func() {
+		if _, err := api.dnsFilter.Compile(); err != nil {
+			slog.Warn("dns-filter: recompile after upload failed", "error", err)
+			return
+		}
+		if err := api.dnsmasq.ReloadService(); err != nil {
+			slog.Warn("dns-filter: reload after upload failed", "error", err)
+		}
+		api.broadcastDNSFilterEvent("dns-filter:updated", "DNS filter list uploaded")
+	}()
+
+	respondJSON(w, http.StatusCreated, map[string]string{
+		"id":      id,
+		"message": "List uploaded",
+	})
+}
+
+// DNSFilterGetSuggested returns well-known blocklists for easy adding.
+func (api *API) DNSFilterGetSuggested(w http.ResponseWriter, r *http.Request) {
+	respondJSON(w, http.StatusOK, map[string]any{
+		"lists": dnsfilter.SuggestedLists(),
+	})
+}

internal/dnsfilter/manager.go

@@ -0,0 +1,550 @@
+package dnsfilter
+
+import (
+	"bufio"
+	"context"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/wild-cloud/wild-central/internal/storage"
+	"gopkg.in/yaml.v3"
+)
+
+// Blocklist represents a subscribed blocklist source.
+type Blocklist struct {
+	ID          string    `yaml:"id" json:"id"`
+	URL         string    `yaml:"url,omitempty" json:"url,omitempty"`
+	Name        string    `yaml:"name" json:"name"`
+	Enabled     bool      `yaml:"enabled" json:"enabled"`
+	EntryCount  int       `yaml:"entryCount,omitempty" json:"entryCount,omitempty"`
+	LastUpdated time.Time `yaml:"lastUpdated,omitempty" json:"lastUpdated,omitzero"`
+	LastError   string    `yaml:"lastError,omitempty" json:"lastError,omitempty"`
+}
+
+// CustomEntry represents a user-managed domain override.
+type CustomEntry struct {
+	Domain string `yaml:"domain" json:"domain"`
+	Type   string `yaml:"type" json:"type"` // "allow" or "block"
+}
+
+// FilterData holds all DNS filter configuration persisted in lists.yaml.
+type FilterData struct {
+	Lists         []Blocklist   `yaml:"lists" json:"lists"`
+	CustomEntries []CustomEntry `yaml:"customEntries" json:"customEntries"`
+}
+
+// FilterStats holds current filtering statistics.
+type FilterStats struct {
+	Enabled      bool      `json:"enabled"`
+	TotalBlocked int       `json:"totalBlocked"`
+	ListCount    int       `json:"listCount"`
+	EnabledLists int       `json:"enabledLists"`
+	LastUpdated  time.Time `json:"lastUpdated"`
+	QueryStats   *QueryStats `json:"queryStats,omitempty"`
+}
+
+// QueryStats holds DNS query statistics from dnsmasq logs.
+type QueryStats struct {
+	TotalQueries   int     `json:"totalQueries"`
+	BlockedQueries int     `json:"blockedQueries"`
+	BlockedPercent float64 `json:"blockedPercent"`
+	Period         string  `json:"period"` // e.g. "24h"
+}
+
+// Manager handles DNS filter list management and compilation.
+type Manager struct {
+	dataDir       string // e.g. /var/lib/wild-central/dns-filter
+	hostsFilePath string // compiled output path (must be readable by dnsmasq)
+}
+
+// NewManager creates a new DNS filter manager.
+func NewManager(dataDir string) *Manager {
+	return &Manager{
+		dataDir:       dataDir,
+		hostsFilePath: filepath.Join(dataDir, "blocked.conf"), // default, override with SetHostsFilePath
+	}
+}
+
+// SetHostsFilePath sets the output path for the compiled hosts file.
+// Must be readable by the dnsmasq process (e.g. /etc/dnsmasq.d/).
+func (m *Manager) SetHostsFilePath(path string) {
+	m.hostsFilePath = path
+}
+
+func (m *Manager) listsPath() string { return filepath.Join(m.dataDir, "lists.yaml") }
+func (m *Manager) cachePath() string { return filepath.Join(m.dataDir, "cache") }
+func (m *Manager) lockPath() string  { return filepath.Join(m.dataDir, "lists.yaml.lock") }
+
+// HostsFilePath returns the path to the compiled blocked hosts file.
+func (m *Manager) HostsFilePath() string { return m.hostsFilePath }
+
+// EnsureDataDir creates the dns-filter directory structure.
+func (m *Manager) EnsureDataDir() error {
+	if err := storage.EnsureDir(m.dataDir, 0755); err != nil {
+		return err
+	}
+	// Also ensure the hosts file output directory exists (may differ from dataDir)
+	hostsDir := filepath.Dir(m.hostsFilePath)
+	if hostsDir != m.dataDir {
+		if err := storage.EnsureDir(hostsDir, 0755); err != nil {
+			return err
+		}
+	}
+	return storage.EnsureDir(m.cachePath(), 0755)
+}
+
+// LoadFilterData reads lists.yaml. Returns empty data if file doesn't exist.
+func (m *Manager) LoadFilterData() (*FilterData, error) {
+	data, err := os.ReadFile(m.listsPath())
+	if err != nil {
+		if os.IsNotExist(err) {
+			return &FilterData{}, nil
+		}
+		return nil, fmt.Errorf("reading filter data: %w", err)
+	}
+	var fd FilterData
+	if err := yaml.Unmarshal(data, &fd); err != nil {
+		return nil, fmt.Errorf("parsing filter data: %w", err)
+	}
+	return &fd, nil
+}
+
+// SaveFilterData writes lists.yaml atomically with file locking.
+func (m *Manager) SaveFilterData(fd *FilterData) error {
+	return storage.WithLock(m.lockPath(), func() error {
+		data, err := yaml.Marshal(fd)
+		if err != nil {
+			return fmt.Errorf("marshaling filter data: %w", err)
+		}
+		return os.WriteFile(m.listsPath(), data, 0644)
+	})
+}
+
+// listID returns a stable ID for a URL-based list.
+func listID(url string) string {
+	h := sha256.Sum256([]byte(url))
+	return fmt.Sprintf("%x", h[:8])
+}
+
+// cacheFile returns the cache file path for a list by ID.
+func (m *Manager) cacheFile(id string) string {
+	return filepath.Join(m.cachePath(), id+".txt")
+}
+
+// AddList adds a URL-based blocklist subscription.
+func (m *Manager) AddList(bl Blocklist) error {
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return err
+	}
+
+	if bl.URL != "" {
+		bl.ID = listID(bl.URL)
+	}
+	if bl.ID == "" {
+		return fmt.Errorf("list must have a URL or ID")
+	}
+
+	// Deduplicate
+	for _, existing := range fd.Lists {
+		if existing.ID == bl.ID {
+			return fmt.Errorf("list already exists: %s", bl.Name)
+		}
+	}
+
+	bl.Enabled = true
+	fd.Lists = append(fd.Lists, bl)
+	return m.SaveFilterData(fd)
+}
+
+// AddUploadedList saves an uploaded blocklist file and adds it as a list entry.
+func (m *Manager) AddUploadedList(name string, content []byte) (string, error) {
+	if err := m.EnsureDataDir(); err != nil {
+		return "", err
+	}
+
+	h := sha256.Sum256(content)
+	id := fmt.Sprintf("upload-%x", h[:8])
+
+	// Write content to cache
+	if err := os.WriteFile(m.cacheFile(id), content, 0644); err != nil {
+		return "", fmt.Errorf("writing uploaded list: %w", err)
+	}
+
+	// Count entries
+	domains, _ := ParseFile(m.cacheFile(id))
+
+	bl := Blocklist{
+		ID:          id,
+		Name:        name,
+		Enabled:     true,
+		EntryCount:  len(domains),
+		LastUpdated: time.Now(),
+	}
+
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return "", err
+	}
+
+	// Deduplicate
+	for _, existing := range fd.Lists {
+		if existing.ID == id {
+			return id, fmt.Errorf("identical list already uploaded")
+		}
+	}
+
+	fd.Lists = append(fd.Lists, bl)
+	return id, m.SaveFilterData(fd)
+}
+
+// RemoveList removes a list by ID and its cached file.
+func (m *Manager) RemoveList(id string) error {
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return err
+	}
+
+	found := false
+	filtered := fd.Lists[:0]
+	for _, bl := range fd.Lists {
+		if bl.ID == id {
+			found = true
+			_ = os.Remove(m.cacheFile(id))
+			continue
+		}
+		filtered = append(filtered, bl)
+	}
+	if !found {
+		return fmt.Errorf("list not found: %s", id)
+	}
+
+	fd.Lists = filtered
+	return m.SaveFilterData(fd)
+}
+
+// ToggleList enables or disables a list by ID.
+func (m *Manager) ToggleList(id string, enabled bool) error {
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return err
+	}
+
+	for i := range fd.Lists {
+		if fd.Lists[i].ID == id {
+			fd.Lists[i].Enabled = enabled
+			return m.SaveFilterData(fd)
+		}
+	}
+	return fmt.Errorf("list not found: %s", id)
+}
+
+// SetCustomEntry adds or replaces a custom allow/block entry.
+func (m *Manager) SetCustomEntry(entry CustomEntry) error {
+	if entry.Type != "allow" && entry.Type != "block" {
+		return fmt.Errorf("type must be 'allow' or 'block'")
+	}
+
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return err
+	}
+
+	// Replace if exists
+	for i := range fd.CustomEntries {
+		if fd.CustomEntries[i].Domain == entry.Domain {
+			fd.CustomEntries[i].Type = entry.Type
+			return m.SaveFilterData(fd)
+		}
+	}
+
+	fd.CustomEntries = append(fd.CustomEntries, entry)
+	return m.SaveFilterData(fd)
+}
+
+// RemoveCustomEntry removes a custom entry by domain.
+func (m *Manager) RemoveCustomEntry(domain string) error {
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return err
+	}
+
+	found := false
+	filtered := fd.CustomEntries[:0]
+	for _, e := range fd.CustomEntries {
+		if e.Domain == domain {
+			found = true
+			continue
+		}
+		filtered = append(filtered, e)
+	}
+	if !found {
+		return fmt.Errorf("custom entry not found: %s", domain)
+	}
+
+	fd.CustomEntries = filtered
+	return m.SaveFilterData(fd)
+}
+
+// UpdateLists downloads all enabled URL-based lists to cache.
+func (m *Manager) UpdateLists(ctx context.Context) error {
+	if err := m.EnsureDataDir(); err != nil {
+		return err
+	}
+
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return err
+	}
+
+	client := &http.Client{Timeout: 60 * time.Second}
+	changed := false
+
+	for i := range fd.Lists {
+		bl := &fd.Lists[i]
+		if !bl.Enabled || bl.URL == "" {
+			continue
+		}
+
+		slog.Info("dns-filter: downloading list", "name", bl.Name, "url", bl.URL)
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, bl.URL, nil)
+		if err != nil {
+			bl.LastError = err.Error()
+			changed = true
+			continue
+		}
+		req.Header.Set("User-Agent", "WildCentral/1.0")
+
+		resp, err := client.Do(req)
+		if err != nil {
+			bl.LastError = fmt.Sprintf("download failed: %v", err)
+			changed = true
+			slog.Warn("dns-filter: download failed", "name", bl.Name, "error", err)
+			continue
+		}
+
+		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+			resp.Body.Close()
+			bl.LastError = fmt.Sprintf("HTTP %d", resp.StatusCode)
+			changed = true
+			slog.Warn("dns-filter: download failed", "name", bl.Name, "status", resp.StatusCode)
+			continue
+		}
+
+		// Limit download to 50MB
+		limited := io.LimitReader(resp.Body, 50*1024*1024)
+		data, err := io.ReadAll(limited)
+		resp.Body.Close()
+		if err != nil {
+			bl.LastError = fmt.Sprintf("read failed: %v", err)
+			changed = true
+			continue
+		}
+
+		if err := os.WriteFile(m.cacheFile(bl.ID), data, 0644); err != nil {
+			bl.LastError = fmt.Sprintf("write failed: %v", err)
+			changed = true
+			continue
+		}
+
+		bl.LastUpdated = time.Now()
+		bl.LastError = ""
+		changed = true
+	}
+
+	if changed {
+		_ = m.SaveFilterData(fd)
+	}
+
+	return nil
+}
+
+// Compile merges all enabled cached lists, applies custom entries,
+// and writes the compiled hosts.blocked file. Returns domain count.
+func (m *Manager) Compile() (int, error) {
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return 0, err
+	}
+
+	blocked := make(map[string]struct{})
+
+	// Parse all enabled lists
+	for i := range fd.Lists {
+		bl := &fd.Lists[i]
+		if !bl.Enabled {
+			continue
+		}
+
+		cachePath := m.cacheFile(bl.ID)
+		if !storage.FileExists(cachePath) {
+			continue
+		}
+
+		domains, err := ParseFile(cachePath)
+		if err != nil {
+			slog.Warn("dns-filter: failed to parse list", "name", bl.Name, "error", err)
+			continue
+		}
+
+		for d := range domains {
+			blocked[d] = struct{}{}
+		}
+		bl.EntryCount = len(domains)
+	}
+
+	// Apply custom entries
+	for _, ce := range fd.CustomEntries {
+		switch ce.Type {
+		case "allow":
+			delete(blocked, ce.Domain)
+		case "block":
+			blocked[ce.Domain] = struct{}{}
+		}
+	}
+
+	// Write hosts.blocked atomically
+	tmpPath := m.HostsFilePath() + ".tmp"
+	f, err := os.Create(tmpPath)
+	if err != nil {
+		return 0, fmt.Errorf("creating hosts file: %w", err)
+	}
+
+	// Sort for deterministic output
+	sorted := make([]string, 0, len(blocked))
+	for d := range blocked {
+		sorted = append(sorted, d)
+	}
+	sort.Strings(sorted)
+
+	w := bufio.NewWriter(f)
+	fmt.Fprintln(w, "# Wild Central DNS Filter — auto-generated, do not edit")
+	for _, d := range sorted {
+		fmt.Fprintf(w, "address=/%s/\n", d)
+	}
+	if err := w.Flush(); err != nil {
+		f.Close()
+		os.Remove(tmpPath)
+		return 0, fmt.Errorf("writing hosts file: %w", err)
+	}
+	f.Close()
+
+	if err := os.Rename(tmpPath, m.HostsFilePath()); err != nil {
+		return 0, fmt.Errorf("renaming hosts file: %w", err)
+	}
+
+	// Update entry counts and save
+	_ = m.SaveFilterData(fd)
+
+	slog.Info("dns-filter: compiled blocklist", "domains", len(sorted))
+	return len(sorted), nil
+}
+
+// GetStats returns current filtering statistics.
+func (m *Manager) GetStats() FilterStats {
+	fd, err := m.LoadFilterData()
+	if err != nil {
+		return FilterStats{}
+	}
+
+	var enabled int
+	var lastUpdated time.Time
+	for _, bl := range fd.Lists {
+		if bl.Enabled {
+			enabled++
+		}
+		if bl.LastUpdated.After(lastUpdated) {
+			lastUpdated = bl.LastUpdated
+		}
+	}
+
+	// Count lines in hosts.blocked for total
+	total := 0
+	if f, err := os.Open(m.HostsFilePath()); err == nil {
+		scanner := bufio.NewScanner(f)
+		for scanner.Scan() {
+			total++
+		}
+		_ = scanner.Err()
+		f.Close()
+	}
+
+	return FilterStats{
+		TotalBlocked: total,
+		ListCount:    len(fd.Lists),
+		EnabledLists: enabled,
+		LastUpdated:  lastUpdated,
+	}
+}
+
+// GetQueryStats parses dnsmasq journal logs to count total and blocked queries.
+// With address=/ directives, blocked queries log as "config <domain> is NXDOMAIN"
+// (for address=/domain/) or "config <domain> is 0.0.0.0".
+func (m *Manager) GetQueryStats() *QueryStats {
+	// Use journalctl to read dnsmasq logs from the last 24 hours.
+	// Run via sudo since the wildcloud user may not be in the systemd-journal group.
+	cmd := exec.Command("sudo", "journalctl", "-u", "dnsmasq", "--since", "24 hours ago", "--no-pager", "-o", "cat")
+	output, err := cmd.Output()
+	if err != nil {
+		slog.Debug("dns-filter: failed to read dnsmasq journal", "error", err)
+		return nil
+	}
+
+	var total, blocked int
+	scanner := bufio.NewScanner(strings.NewReader(string(output)))
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.Contains(line, "query[") {
+			total++
+		}
+		// dnsmasq logs address=/ blocks as: "config <domain> is NXDOMAIN"
+		// and addn-hosts blocks as: "/path/file <domain> is 0.0.0.0"
+		if strings.HasPrefix(line, "config ") && strings.Contains(line, " is NXDOMAIN") {
+			blocked++
+		}
+	}
+
+	var pct float64
+	if total > 0 {
+		pct = float64(blocked) / float64(total) * 100
+	}
+
+	return &QueryStats{
+		TotalQueries:   total,
+		BlockedQueries: blocked,
+		BlockedPercent: pct,
+		Period:         "24h",
+	}
+}
+
+// SuggestedLists returns well-known blocklists for easy adding.
+// Prefers dnsmasq-format lists which support wildcard subdomain blocking.
+func SuggestedLists() []Blocklist {
+	type entry struct {
+		url  string
+		name string
+	}
+	lists := []entry{
+		{"https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts", "Steven Black - Unified Hosts"},
+		{"https://cdn.jsdelivr.net/gh/hagezi/dns-blocklists@latest/dnsmasq/light.txt", "Hagezi - Light"},
+		{"https://cdn.jsdelivr.net/gh/hagezi/dns-blocklists@latest/dnsmasq/pro.txt", "Hagezi - Pro"},
+		{"https://cdn.jsdelivr.net/gh/hagezi/dns-blocklists@latest/dnsmasq/ultimate.txt", "Hagezi - Ultimate"},
+		{"https://big.oisd.nl/dnsmasq2", "OISD - Big"},
+		{"https://small.oisd.nl/dnsmasq2", "OISD - Small"},
+	}
+	result := make([]Blocklist, len(lists))
+	for i, l := range lists {
+		result[i] = Blocklist{ID: listID(l.url), URL: l.url, Name: l.name}
+	}
+	return result
+}

internal/dnsfilter/parser.go

@@ -0,0 +1,89 @@
+package dnsfilter
+
+import (
+	"bufio"
+	"net"
+	"os"
+	"strings"
+)
+
+// ParseLine extracts a domain from a single blocklist line.
+// Handles hosts format (0.0.0.0 domain), dnsmasq format (address=/domain/...),
+// and plain domain lists. Returns empty string and false for unparseable lines.
+func ParseLine(line string) (string, bool) {
+	line = strings.TrimSpace(line)
+	if line == "" || line[0] == '#' || line[0] == '!' {
+		return "", false
+	}
+
+	// dnsmasq format: address=/domain/0.0.0.0 or server=/domain/
+	if strings.HasPrefix(line, "address=/") || strings.HasPrefix(line, "server=/") {
+		parts := strings.SplitN(line, "/", 4)
+		if len(parts) >= 3 && parts[1] != "" {
+			return validateDomain(parts[1])
+		}
+		return "", false
+	}
+
+	// Hosts format: 0.0.0.0 domain or 127.0.0.1 domain
+	fields := strings.Fields(line)
+	if len(fields) >= 2 {
+		ip := fields[0]
+		if ip == "0.0.0.0" || ip == "127.0.0.1" || ip == "::1" || ip == "::0" {
+			domain := fields[1]
+			// Strip inline comments
+			if i := strings.IndexByte(domain, '#'); i >= 0 {
+				domain = domain[:i]
+			}
+			return validateDomain(domain)
+		}
+	}
+
+	// Plain domain format: one domain per line
+	if len(fields) == 1 {
+		return validateDomain(fields[0])
+	}
+
+	return "", false
+}
+
+// validateDomain checks that a string looks like a valid domain for blocking.
+func validateDomain(d string) (string, bool) {
+	d = strings.ToLower(strings.TrimSpace(d))
+	if d == "" || !strings.Contains(d, ".") {
+		return "", false
+	}
+
+	// Reject known non-domains
+	switch d {
+	case "localhost", "localhost.localdomain", "local", "broadcasthost",
+		"ip6-localhost", "ip6-loopback", "ip6-localnet",
+		"ip6-mcastprefix", "ip6-allnodes", "ip6-allrouters":
+		return "", false
+	}
+
+	// Reject IP addresses
+	if net.ParseIP(d) != nil {
+		return "", false
+	}
+
+	return d, true
+}
+
+// ParseFile reads a cached blocklist file and returns all unique domains.
+func ParseFile(path string) (map[string]struct{}, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	domains := make(map[string]struct{})
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		if domain, ok := ParseLine(scanner.Text()); ok {
+			domains[domain] = struct{}{}
+		}
+	}
+	return domains, scanner.Err()
+}

internal/dnsfilter/parser_test.go

@@ -0,0 +1,141 @@
+package dnsfilter
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestParseLine_HostsFormat(t *testing.T) {
+	tests := []struct {
+		line   string
+		want   string
+		wantOK bool
+	}{
+		{"0.0.0.0 ads.example.com", "ads.example.com", true},
+		{"127.0.0.1 tracker.example.com", "tracker.example.com", true},
+		{"0.0.0.0 ads.example.com # comment", "ads.example.com", true},
+		{"::1 ads.example.com", "ads.example.com", true},
+		{"0.0.0.0 localhost", "", false},
+		{"0.0.0.0 broadcasthost", "", false},
+		{"0.0.0.0 localhost.localdomain", "", false},
+		{"127.0.0.1 local", "", false},
+	}
+
+	for _, tt := range tests {
+		got, ok := ParseLine(tt.line)
+		if ok != tt.wantOK || got != tt.want {
+			t.Errorf("ParseLine(%q) = (%q, %v), want (%q, %v)", tt.line, got, ok, tt.want, tt.wantOK)
+		}
+	}
+}
+
+func TestParseLine_DnsmasqFormat(t *testing.T) {
+	tests := []struct {
+		line   string
+		want   string
+		wantOK bool
+	}{
+		{"address=/ads.example.com/0.0.0.0", "ads.example.com", true},
+		{"address=/tracker.example.com/", "tracker.example.com", true},
+		{"server=/blocked.example.com/", "blocked.example.com", true},
+		{"address=//", "", false},
+	}
+
+	for _, tt := range tests {
+		got, ok := ParseLine(tt.line)
+		if ok != tt.wantOK || got != tt.want {
+			t.Errorf("ParseLine(%q) = (%q, %v), want (%q, %v)", tt.line, got, ok, tt.want, tt.wantOK)
+		}
+	}
+}
+
+func TestParseLine_PlainDomain(t *testing.T) {
+	tests := []struct {
+		line   string
+		want   string
+		wantOK bool
+	}{
+		{"ads.example.com", "ads.example.com", true},
+		{"TRACKER.Example.COM", "tracker.example.com", true},
+		{"nodot", "", false},
+		{"# comment", "", false},
+		{"", "", false},
+		{"  ", "", false},
+		{"192.168.1.1", "", false},
+	}
+
+	for _, tt := range tests {
+		got, ok := ParseLine(tt.line)
+		if ok != tt.wantOK || got != tt.want {
+			t.Errorf("ParseLine(%q) = (%q, %v), want (%q, %v)", tt.line, got, ok, tt.want, tt.wantOK)
+		}
+	}
+}
+
+func TestParseFile(t *testing.T) {
+	content := `# Steven Black hosts file
+0.0.0.0 localhost
+0.0.0.0 ads.example.com
+0.0.0.0 tracker.example.com
+127.0.0.1 more-ads.example.com
+# duplicate
+0.0.0.0 ads.example.com
+`
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.hosts")
+	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	domains, err := ParseFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Should have 3 unique domains (localhost excluded)
+	if len(domains) != 3 {
+		t.Errorf("got %d domains, want 3", len(domains))
+	}
+
+	for _, expected := range []string{"ads.example.com", "tracker.example.com", "more-ads.example.com"} {
+		if _, ok := domains[expected]; !ok {
+			t.Errorf("missing expected domain: %s", expected)
+		}
+	}
+}
+
+func TestParseFile_MixedFormats(t *testing.T) {
+	content := `# Mixed format file
+0.0.0.0 hosts-format.example.com
+address=/dnsmasq-format.example.com/0.0.0.0
+plain-domain.example.com
+! adblock comment
+127.0.0.1 another.example.com
+`
+	dir := t.TempDir()
+	path := filepath.Join(dir, "mixed.txt")
+	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	domains, err := ParseFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(domains) != 4 {
+		t.Errorf("got %d domains, want 4", len(domains))
+	}
+
+	for _, expected := range []string{
+		"hosts-format.example.com",
+		"dnsmasq-format.example.com",
+		"plain-domain.example.com",
+		"another.example.com",
+	} {
+		if _, ok := domains[expected]; !ok {
+			t.Errorf("missing expected domain: %s", expected)
+		}
+	}
+}

internal/dnsfilter/runner.go

@@ -0,0 +1,115 @@
+package dnsfilter
+
+import (
+	"context"
+	"log/slog"
+	"sync"
+	"time"
+)
+
+// Runner manages the background blocklist update goroutine.
+type Runner struct {
+	mu       sync.RWMutex
+	manager  *Manager
+	cancel   context.CancelFunc
+	trigger  chan struct{}
+	running  bool
+	onUpdate func() // called after lists are downloaded and compiled
+}
+
+// NewRunner creates a new DNS filter update runner.
+func NewRunner(manager *Manager, onUpdate func()) *Runner {
+	return &Runner{
+		manager:  manager,
+		trigger:  make(chan struct{}, 1),
+		onUpdate: onUpdate,
+	}
+}
+
+// Start launches the background update goroutine.
+// Safe to call multiple times — cancels the previous run first.
+func (r *Runner) Start(parentCtx context.Context, intervalHours int) {
+	r.mu.Lock()
+	if r.cancel != nil {
+		r.cancel()
+	}
+
+	ctx, cancel := context.WithCancel(parentCtx)
+	r.cancel = cancel
+	r.running = true
+	r.mu.Unlock()
+
+	if intervalHours <= 0 {
+		intervalHours = 24
+	}
+
+	go r.run(ctx, intervalHours)
+}
+
+// Stop cancels the running goroutine.
+func (r *Runner) Stop() {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.cancel != nil {
+		r.cancel()
+		r.cancel = nil
+	}
+	r.running = false
+}
+
+// IsRunning returns whether the runner is active.
+func (r *Runner) IsRunning() bool {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	return r.running
+}
+
+// Trigger requests an immediate update (non-blocking).
+func (r *Runner) Trigger() {
+	select {
+	case r.trigger <- struct{}{}:
+	default:
+	}
+}
+
+func (r *Runner) run(ctx context.Context, intervalHours int) {
+	interval := time.Duration(intervalHours) * time.Hour
+
+	slog.Info("dns-filter: runner started", "interval", interval)
+
+	// Immediate update on start
+	r.updateAndCompile(ctx)
+
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			r.mu.Lock()
+			r.running = false
+			r.mu.Unlock()
+			slog.Info("dns-filter: runner stopped")
+			return
+		case <-ticker.C:
+			r.updateAndCompile(ctx)
+		case <-r.trigger:
+			r.updateAndCompile(ctx)
+		}
+	}
+}
+
+func (r *Runner) updateAndCompile(ctx context.Context) {
+	if err := r.manager.UpdateLists(ctx); err != nil {
+		slog.Error("dns-filter: update failed", "error", err)
+	}
+
+	if _, err := r.manager.Compile(); err != nil {
+		slog.Error("dns-filter: compile failed", "error", err)
+		return
+	}
+
+	if r.onUpdate != nil {
+		r.onUpdate()
+	}
+}

internal/dnsmasq/config.go

@@ -26,7 +26,8 @@ type DNSEntry struct {
 
 // ConfigGenerator handles dnsmasq configuration generation
 type ConfigGenerator struct {
-	configPath string
+	configPath    string
+	filterConfPath string // path to addn-hosts file for DNS filtering
 }
 
 // NewConfigGenerator creates a new dnsmasq config generator
@@ -44,6 +45,12 @@ func (g *ConfigGenerator) GetConfigPath() string {
 	return g.configPath
 }
 
+// SetFilterConfPath sets the path to an additional hosts file for DNS filtering.
+// When set, the generated config includes an addn-hosts= directive.
+func (g *ConfigGenerator) SetFilterConfPath(path string) {
+	g.filterConfPath = path
+}
+
 // Generate creates a dnsmasq configuration from registered domain entries.
 // It auto-detects the Wild Central server's IP address for the listen directive.
 func (g *ConfigGenerator) Generate(cfg *config.State, entries []DNSEntry) string {
@@ -94,10 +101,16 @@ log-queries
 log-dhcp
 `
 
-	return fmt.Sprintf(template,
+	result := fmt.Sprintf(template,
 		dnsIP,
 		resolution_section,
 	)
+
+	if g.filterConfPath != "" {
+		result += fmt.Sprintf("\n# DNS Filtering\nconf-file=%s\n", g.filterConfPath)
+	}
+
+	return result
 }
 
 // RestartService reloads the dnsmasq service (SIGHUP — no downtime).
@@ -270,6 +283,10 @@ log-dhcp
 		}
 	}
 
+	if g.filterConfPath != "" {
+		fmt.Fprintf(&sb, "\n# DNS Filtering\nconf-file=%s\n", g.filterConfPath)
+	}
+
 	return sb.String()
 }
 

internal/dnsmasq/config_test.go

@@ -313,6 +313,43 @@ func TestGenerate_MultipleEntries(t *testing.T) {
 	}
 }
 
+func TestGenerate_ConfFile(t *testing.T) {
+	g := NewConfigGenerator("/tmp/test-dnsmasq.conf")
+	g.SetFilterConfPath("/var/lib/wild-central/dns-filter/hosts.blocked")
+
+	out := g.Generate(nil, nil)
+
+	if !strings.Contains(out, "conf-file=/var/lib/wild-central/dns-filter/hosts.blocked") {
+		t.Errorf("expected addn-hosts directive, got:\n%s", out)
+	}
+	if !strings.Contains(out, "# DNS Filtering") {
+		t.Errorf("expected DNS Filtering comment, got:\n%s", out)
+	}
+}
+
+func TestGenerate_NoConfFileWhenEmpty(t *testing.T) {
+	g := NewConfigGenerator("/tmp/test-dnsmasq.conf")
+	// addnHostsPath is empty by default
+
+	out := g.Generate(nil, nil)
+
+	if strings.Contains(out, "addn-hosts") {
+		t.Errorf("should not contain addn-hosts when path is empty, got:\n%s", out)
+	}
+}
+
+func TestGenerateMainConfig_ConfFile(t *testing.T) {
+	g := NewConfigGenerator("/tmp/test-dnsmasq.conf")
+	g.SetFilterConfPath("/tmp/hosts.blocked")
+
+	cfg := &config.State{}
+	out := g.GenerateMainConfig(cfg)
+
+	if !strings.Contains(out, "conf-file=/tmp/hosts.blocked") {
+		t.Errorf("expected addn-hosts in main config, got:\n%s", out)
+	}
+}
+
 // Test: nil config doesn't panic, uses auto-detect for IP
 func TestGenerate_NilConfig(t *testing.T) {
 	g := NewConfigGenerator("/tmp/test-dnsmasq.conf")

main.go

@@ -123,6 +123,7 @@ func main() {
 	slog.Info("central status broadcaster started")
 
 	api.StartDDNS(ctx)
+	api.StartDNSFilter(ctx)
 
 	router := mux.NewRouter()
 	api.RegisterRoutes(router)

web/src/components/DnsFilterComponent.tsx

@@ -0,0 +1,501 @@
+import { useState, useRef } from 'react';
+import { Card, CardHeader, CardTitle, CardContent } from './ui/card';
+import { Button } from './ui/button';
+import { Input, Label } from './ui';
+import { Alert, AlertDescription } from './ui/alert';
+import { Switch } from './ui/switch';
+import { Badge } from './ui/badge';
+import { Select, SelectTrigger, SelectValue, SelectContent, SelectItem } from './ui/select';
+import {
+  ShieldBan, Loader2, Plus, Trash2, RotateCw, Upload,
+  CheckCircle, AlertCircle, X, ExternalLink, List,
+} from 'lucide-react';
+import { useDnsFilter } from '../hooks/useDnsFilter';
+
+export function DnsFilterComponent() {
+  const {
+    status, isLoadingStatus, config,
+    lists, customEntries, suggestedLists,
+    updateConfig, isUpdatingConfig,
+    addList, isAddingList,
+    removeList, toggleList,
+    addCustomEntry, removeCustomEntry,
+    triggerUpdate, isUpdating,
+    uploadList, isUploading,
+  } = useDnsFilter();
+
+  const [successMessage, setSuccessMessage] = useState<string | null>(null);
+  const [errorMessage, setErrorMessage] = useState<string | null>(null);
+
+  // Add list form
+  const [newListUrl, setNewListUrl] = useState('');
+  const [newListName, setNewListName] = useState('');
+  const [showAddList, setShowAddList] = useState(false);
+
+  // Upload form
+  const [uploadName, setUploadName] = useState('');
+  const fileInputRef = useRef<HTMLInputElement>(null);
+
+  // Custom entry form
+  const [showAddCustom, setShowAddCustom] = useState(false);
+  const [newCustomDomain, setNewCustomDomain] = useState('');
+  const [newCustomType, setNewCustomType] = useState<'allow' | 'block'>('block');
+
+  const showSuccess = (msg: string) => {
+    setSuccessMessage(msg);
+    setErrorMessage(null);
+    setTimeout(() => setSuccessMessage(null), 5000);
+  };
+
+  const showError = (msg: string) => {
+    setErrorMessage(msg);
+    setSuccessMessage(null);
+    setTimeout(() => setErrorMessage(null), 8000);
+  };
+
+  const handleToggleEnabled = async () => {
+    try {
+      await updateConfig({ enabled: !status?.enabled });
+      showSuccess(status?.enabled ? 'DNS filtering disabled' : 'DNS filtering enabled');
+    } catch (e) {
+      showError(`Failed to update config: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleAddList = async () => {
+    if (!newListUrl || !newListName) return;
+    try {
+      await addList({ url: newListUrl, name: newListName });
+      setNewListUrl('');
+      setNewListName('');
+      setShowAddList(false);
+      showSuccess(`Added list: ${newListName}`);
+    } catch (e) {
+      showError(`Failed to add list: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleAddSuggested = async (url: string, name: string) => {
+    try {
+      await addList({ url, name });
+      showSuccess(`Added list: ${name}`);
+    } catch (e) {
+      showError(`Failed to add list: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleUpload = async () => {
+    const file = fileInputRef.current?.files?.[0];
+    if (!file || !uploadName) return;
+    try {
+      await uploadList({ name: uploadName, file });
+      setUploadName('');
+      if (fileInputRef.current) fileInputRef.current.value = '';
+      showSuccess(`Uploaded list: ${uploadName}`);
+    } catch (e) {
+      showError(`Failed to upload: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleRemoveList = async (id: string) => {
+    try {
+      await removeList(id);
+      showSuccess('List removed');
+    } catch (e) {
+      showError(`Failed to remove list: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleToggleList = async (id: string, enabled: boolean) => {
+    try {
+      await toggleList({ id, enabled });
+    } catch (e) {
+      showError(`Failed to toggle list: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleAddCustom = async () => {
+    if (!newCustomDomain) return;
+    try {
+      await addCustomEntry({ domain: newCustomDomain, type: newCustomType });
+      setNewCustomDomain('');
+      setShowAddCustom(false);
+      showSuccess(`Added ${newCustomType} entry for ${newCustomDomain}`);
+    } catch (e) {
+      showError(`Failed to add entry: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleRemoveCustom = async (domain: string) => {
+    try {
+      await removeCustomEntry(domain);
+      showSuccess('Custom entry removed');
+    } catch (e) {
+      showError(`Failed to remove entry: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  const handleTriggerUpdate = async () => {
+    try {
+      await triggerUpdate();
+      showSuccess('Update triggered — lists will refresh in the background');
+    } catch (e) {
+      showError(`Failed to trigger update: ${e instanceof Error ? e.message : String(e)}`);
+    }
+  };
+
+  // Filter suggested lists to exclude already-added ones
+  const addedIds = new Set(lists.map(l => l.id));
+  const availableSuggested = suggestedLists.filter(s => !addedIds.has(s.id));
+
+  return (
+    <div className="space-y-6">
+      {/* Header */}
+      <div className="flex items-center gap-4">
+        <div className="p-2 bg-primary/10 rounded-lg">
+          <ShieldBan className="h-6 w-6 text-primary" />
+        </div>
+        <div>
+          <h2 className="text-2xl font-semibold">DNS Filter</h2>
+          <p className="text-muted-foreground">Block ads, trackers, and malware at the DNS level</p>
+        </div>
+      </div>
+
+      {/* Alerts */}
+      {successMessage && (
+        <Alert className="border-green-500 bg-green-50 dark:bg-green-900/20">
+          <CheckCircle className="h-4 w-4 text-green-600" />
+          <AlertDescription className="flex items-center justify-between">
+            <span className="text-green-800 dark:text-green-200">{successMessage}</span>
+            <Button variant="ghost" size="sm" onClick={() => setSuccessMessage(null)}><X className="h-3 w-3" /></Button>
+          </AlertDescription>
+        </Alert>
+      )}
+      {errorMessage && (
+        <Alert variant="error">
+          <AlertCircle className="h-4 w-4" />
+          <AlertDescription className="flex items-center justify-between">
+            <span>{errorMessage}</span>
+            <Button variant="ghost" size="sm" onClick={() => setErrorMessage(null)}><X className="h-3 w-3" /></Button>
+          </AlertDescription>
+        </Alert>
+      )}
+
+      {/* Status Card */}
+      <Card className="border-l-4 border-l-blue-500">
+        <CardHeader>
+          <div className="flex items-center justify-between">
+            <CardTitle className="text-lg">Status</CardTitle>
+            <div className="flex items-center gap-3">
+              {status?.enabled && (
+                <Button
+                  variant="outline"
+                  size="sm"
+                  onClick={handleTriggerUpdate}
+                  disabled={isUpdating}
+                >
+                  {isUpdating ? <Loader2 className="h-4 w-4 animate-spin mr-1" /> : <RotateCw className="h-4 w-4 mr-1" />}
+                  Update Now
+                </Button>
+              )}
+              <div className="flex items-center gap-2">
+                <Label htmlFor="dns-filter-toggle" className="text-sm">
+                  {status?.enabled ? 'Enabled' : 'Disabled'}
+                </Label>
+                <Switch
+                  id="dns-filter-toggle"
+                  checked={status?.enabled ?? false}
+                  onCheckedChange={handleToggleEnabled}
+                  disabled={isUpdatingConfig || isLoadingStatus}
+                />
+              </div>
+            </div>
+          </div>
+        </CardHeader>
+        {status?.enabled && (
+          <CardContent className="space-y-4">
+            {/* Query stats */}
+            {status.queryStats && (
+              <div className="grid grid-cols-3 gap-4">
+                <div className="bg-muted rounded-md p-3 text-center">
+                  <p className="text-2xl font-bold font-mono">{status.queryStats.totalQueries.toLocaleString()}</p>
+                  <p className="text-xs text-muted-foreground">Queries ({status.queryStats.period})</p>
+                </div>
+                <div className="bg-muted rounded-md p-3 text-center">
+                  <p className="text-2xl font-bold font-mono text-red-500">{status.queryStats.blockedQueries.toLocaleString()}</p>
+                  <p className="text-xs text-muted-foreground">Blocked</p>
+                </div>
+                <div className="bg-muted rounded-md p-3 text-center">
+                  <p className="text-2xl font-bold font-mono text-red-500">{status.queryStats.blockedPercent.toFixed(1)}%</p>
+                  <p className="text-xs text-muted-foreground">Block rate</p>
+                </div>
+              </div>
+            )}
+
+            {/* List stats */}
+            <div className="grid grid-cols-2 sm:grid-cols-4 gap-4">
+              <div className="bg-muted rounded-md p-3 text-center">
+                <p className="text-2xl font-bold font-mono">{status.totalBlocked.toLocaleString()}</p>
+                <p className="text-xs text-muted-foreground">Domains in blocklist</p>
+              </div>
+              <div className="bg-muted rounded-md p-3 text-center">
+                <p className="text-2xl font-bold font-mono">{status.enabledLists}</p>
+                <p className="text-xs text-muted-foreground">Active lists</p>
+              </div>
+              <div className="bg-muted rounded-md p-3 text-center">
+                <p className="text-2xl font-bold font-mono">{status.listCount}</p>
+                <p className="text-xs text-muted-foreground">Total lists</p>
+              </div>
+              <div className="bg-muted rounded-md p-3 text-center">
+                <p className="text-sm font-mono">
+                  {status.lastUpdated ? new Date(status.lastUpdated).toLocaleString() : 'Never'}
+                </p>
+                <p className="text-xs text-muted-foreground">Last updated</p>
+              </div>
+            </div>
+            {config && (
+              <p className="text-sm text-muted-foreground">
+                Lists update every {config.intervalHours || 24} hours
+              </p>
+            )}
+          </CardContent>
+        )}
+      </Card>
+
+      {/* Blocklists Card */}
+      <Card className="border-l-4 border-l-green-500">
+        <CardHeader>
+          <div className="flex items-center justify-between">
+            <CardTitle className="text-lg flex items-center gap-2">
+              <List className="h-5 w-5" />
+              Blocklists
+            </CardTitle>
+            <div className="flex gap-2">
+              <Button variant="outline" size="sm" onClick={() => setShowAddList(!showAddList)}>
+                <Plus className="h-4 w-4 mr-1" />
+                Add List
+              </Button>
+            </div>
+          </div>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          {/* Add list form */}
+          {showAddList && (
+            <Card className="p-4 bg-muted/50">
+              <div className="space-y-3">
+                <h4 className="font-medium text-sm">Add blocklist by URL</h4>
+                <div>
+                  <Label htmlFor="list-name">Name</Label>
+                  <Input
+                    id="list-name"
+                    placeholder="e.g. My Custom Blocklist"
+                    value={newListName}
+                    onChange={e => setNewListName(e.target.value)}
+                    className="mt-1"
+                  />
+                </div>
+                <div>
+                  <Label htmlFor="list-url">URL</Label>
+                  <Input
+                    id="list-url"
+                    placeholder="https://example.com/blocklist.txt"
+                    value={newListUrl}
+                    onChange={e => setNewListUrl(e.target.value)}
+                    className="mt-1"
+                  />
+                </div>
+                <div className="flex gap-2">
+                  <Button size="sm" onClick={handleAddList} disabled={isAddingList || !newListUrl || !newListName}>
+                    {isAddingList ? <Loader2 className="h-4 w-4 animate-spin mr-1" /> : <Plus className="h-4 w-4 mr-1" />}
+                    Add
+                  </Button>
+                  <Button variant="ghost" size="sm" onClick={() => setShowAddList(false)}>Cancel</Button>
+                </div>
+
+                {/* Upload */}
+                <div className="border-t pt-3 mt-3">
+                  <h4 className="font-medium text-sm mb-2">Or upload a file</h4>
+                  <div className="flex gap-2 items-end">
+                    <div className="flex-1">
+                      <Label htmlFor="upload-name">Name</Label>
+                      <Input
+                        id="upload-name"
+                        placeholder="My uploaded list"
+                        value={uploadName}
+                        onChange={e => setUploadName(e.target.value)}
+                        className="mt-1"
+                      />
+                    </div>
+                    <div className="flex-1">
+                      <Label htmlFor="upload-file">File</Label>
+                      <Input id="upload-file" type="file" ref={fileInputRef} accept=".txt,.hosts,.conf" className="mt-1" />
+                    </div>
+                    <Button size="sm" onClick={handleUpload} disabled={isUploading || !uploadName}>
+                      {isUploading ? <Loader2 className="h-4 w-4 animate-spin mr-1" /> : <Upload className="h-4 w-4 mr-1" />}
+                      Upload
+                    </Button>
+                  </div>
+                </div>
+              </div>
+            </Card>
+          )}
+
+          {/* Current lists */}
+          {lists.length === 0 ? (
+            <div className="text-center py-8 text-muted-foreground">
+              <ShieldBan className="h-12 w-12 mx-auto mb-3 opacity-50" />
+              <p className="font-medium">No blocklists added</p>
+              <p className="text-sm mt-1">Add a blocklist URL or choose from the suggestions below</p>
+            </div>
+          ) : (
+            <div className="space-y-2">
+              {lists.map(list => (
+                <div key={list.id} className="flex items-center gap-3 p-3 bg-muted/50 rounded-md">
+                  <Switch
+                    checked={list.enabled}
+                    onCheckedChange={(checked) => handleToggleList(list.id, checked)}
+                  />
+                  <div className="flex-1 min-w-0">
+                    <div className="flex items-center gap-2">
+                      <span className="font-medium text-sm truncate">{list.name}</span>
+                      {list.entryCount > 0 && (
+                        <Badge variant="secondary" className="text-xs">
+                          {list.entryCount.toLocaleString()} domains
+                        </Badge>
+                      )}
+                      {list.lastError && (
+                        <Badge variant="destructive" className="text-xs">Error</Badge>
+                      )}
+                    </div>
+                    {list.url && (
+                      <p className="text-xs text-muted-foreground font-mono truncate mt-0.5">{list.url}</p>
+                    )}
+                    {!list.url && (
+                      <p className="text-xs text-muted-foreground mt-0.5">Uploaded file</p>
+                    )}
+                    {list.lastError && (
+                      <p className="text-xs text-red-500 mt-0.5">{list.lastError}</p>
+                    )}
+                  </div>
+                  <Button variant="ghost" size="sm" onClick={() => handleRemoveList(list.id)}>
+                    <Trash2 className="h-4 w-4 text-muted-foreground hover:text-destructive" />
+                  </Button>
+                </div>
+              ))}
+            </div>
+          )}
+
+          {/* Suggested lists */}
+          {availableSuggested.length > 0 && (
+            <div className="border-t pt-4 mt-4">
+              <h4 className="text-sm font-medium mb-3 text-muted-foreground">Suggested lists</h4>
+              <div className="space-y-2">
+                {availableSuggested.map(suggested => (
+                  <div key={suggested.id} className="flex items-center gap-3 p-2 rounded-md hover:bg-muted/50 transition-colors">
+                    <div className="flex-1 min-w-0">
+                      <span className="text-sm font-medium">{suggested.name}</span>
+                      {suggested.url && (
+                        <p className="text-xs text-muted-foreground font-mono truncate">{suggested.url}</p>
+                      )}
+                    </div>
+                    <div className="flex gap-1">
+                      {suggested.url && (
+                        <Button variant="ghost" size="sm" asChild>
+                          <a href={suggested.url} target="_blank" rel="noopener noreferrer">
+                            <ExternalLink className="h-3.5 w-3.5" />
+                          </a>
+                        </Button>
+                      )}
+                      <Button
+                        variant="outline"
+                        size="sm"
+                        onClick={() => handleAddSuggested(suggested.url!, suggested.name)}
+                        disabled={isAddingList}
+                      >
+                        <Plus className="h-3.5 w-3.5 mr-1" />
+                        Add
+                      </Button>
+                    </div>
+                  </div>
+                ))}
+              </div>
+            </div>
+          )}
+        </CardContent>
+      </Card>
+
+      {/* Custom Entries Card */}
+      <Card className="border-l-4 border-l-blue-500">
+        <CardHeader>
+          <div className="flex items-center justify-between">
+            <CardTitle className="text-lg">Custom Entries</CardTitle>
+            <Button variant="outline" size="sm" onClick={() => setShowAddCustom(!showAddCustom)}>
+              <Plus className="h-4 w-4 mr-1" />
+              Add Entry
+            </Button>
+          </div>
+        </CardHeader>
+        <CardContent className="space-y-4">
+          {showAddCustom && (
+            <Card className="p-4 bg-muted/50">
+              <div className="space-y-3">
+                <div className="flex gap-3 items-end">
+                  <div className="flex-1">
+                    <Label htmlFor="custom-domain">Domain</Label>
+                    <Input
+                      id="custom-domain"
+                      placeholder="ads.example.com"
+                      value={newCustomDomain}
+                      onChange={e => setNewCustomDomain(e.target.value)}
+                      className="mt-1 font-mono"
+                    />
+                  </div>
+                  <div className="w-32">
+                    <Label htmlFor="custom-type">Type</Label>
+                    <Select value={newCustomType} onValueChange={(v) => setNewCustomType(v as 'allow' | 'block')}>
+                      <SelectTrigger className="mt-1">
+                        <SelectValue />
+                      </SelectTrigger>
+                      <SelectContent>
+                        <SelectItem value="block">Block</SelectItem>
+                        <SelectItem value="allow">Allow</SelectItem>
+                      </SelectContent>
+                    </Select>
+                  </div>
+                  <Button size="sm" onClick={handleAddCustom} disabled={!newCustomDomain}>
+                    <Plus className="h-4 w-4 mr-1" />
+                    Add
+                  </Button>
+                  <Button variant="ghost" size="sm" onClick={() => setShowAddCustom(false)}>Cancel</Button>
+                </div>
+                <p className="text-xs text-muted-foreground">
+                  <strong>Block</strong> adds a domain to the blocklist. <strong>Allow</strong> overrides blocklists to permit a specific domain.
+                </p>
+              </div>
+            </Card>
+          )}
+
+          {customEntries.length === 0 ? (
+            <p className="text-sm text-muted-foreground text-center py-4">
+              No custom entries. Use allow entries to override blocklists for specific domains.
+            </p>
+          ) : (
+            <div className="space-y-1">
+              {customEntries.map(entry => (
+                <div key={entry.domain} className="flex items-center gap-3 p-2 rounded-md hover:bg-muted/50">
+                  <Badge variant={entry.type === 'block' ? 'destructive' : 'default'} className="text-xs w-14 justify-center">
+                    {entry.type}
+                  </Badge>
+                  <span className="flex-1 font-mono text-sm">{entry.domain}</span>
+                  <Button variant="ghost" size="sm" onClick={() => handleRemoveCustom(entry.domain)}>
+                    <Trash2 className="h-4 w-4 text-muted-foreground hover:text-destructive" />
+                  </Button>
+                </div>
+              ))}
+            </div>
+          )}
+        </CardContent>
+      </Card>
+    </div>
+  );
+}

web/src/hooks/useDnsFilter.ts

@@ -0,0 +1,101 @@
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { dnsFilterApi, type CustomEntry } from '../services/api/dnsfilter';
+
+export function useDnsFilter() {
+  const queryClient = useQueryClient();
+
+  const statusQuery = useQuery({
+    queryKey: ['dns-filter', 'status'],
+    queryFn: () => dnsFilterApi.getStatus(),
+  });
+
+  const configQuery = useQuery({
+    queryKey: ['dns-filter', 'config'],
+    queryFn: () => dnsFilterApi.getConfig(),
+  });
+
+  const listsQuery = useQuery({
+    queryKey: ['dns-filter', 'lists'],
+    queryFn: () => dnsFilterApi.getLists(),
+  });
+
+  const customQuery = useQuery({
+    queryKey: ['dns-filter', 'custom'],
+    queryFn: () => dnsFilterApi.getCustomEntries(),
+  });
+
+  const suggestedQuery = useQuery({
+    queryKey: ['dns-filter', 'suggested'],
+    queryFn: () => dnsFilterApi.getSuggested(),
+    staleTime: Infinity,
+  });
+
+  const invalidateAll = () => {
+    queryClient.invalidateQueries({ queryKey: ['dns-filter'] });
+  };
+
+  const updateConfigMutation = useMutation({
+    mutationFn: dnsFilterApi.updateConfig,
+    onSuccess: invalidateAll,
+  });
+
+  const addListMutation = useMutation({
+    mutationFn: (data: { url: string; name: string }) => dnsFilterApi.addList(data),
+    onSuccess: invalidateAll,
+  });
+
+  const removeListMutation = useMutation({
+    mutationFn: (id: string) => dnsFilterApi.removeList(id),
+    onSuccess: invalidateAll,
+  });
+
+  const toggleListMutation = useMutation({
+    mutationFn: ({ id, enabled }: { id: string; enabled: boolean }) => dnsFilterApi.toggleList(id, enabled),
+    onSuccess: invalidateAll,
+  });
+
+  const addCustomMutation = useMutation({
+    mutationFn: (entry: CustomEntry) => dnsFilterApi.setCustomEntry(entry),
+    onSuccess: invalidateAll,
+  });
+
+  const removeCustomMutation = useMutation({
+    mutationFn: (domain: string) => dnsFilterApi.removeCustomEntry(domain),
+    onSuccess: invalidateAll,
+  });
+
+  const triggerUpdateMutation = useMutation({
+    mutationFn: () => dnsFilterApi.triggerUpdate(),
+    onSuccess: () => {
+      // Delay invalidation to give the runner time to download + compile
+      setTimeout(invalidateAll, 3000);
+    },
+  });
+
+  const uploadListMutation = useMutation({
+    mutationFn: ({ name, file }: { name: string; file: File }) => dnsFilterApi.uploadList(name, file),
+    onSuccess: invalidateAll,
+  });
+
+  return {
+    status: statusQuery.data,
+    isLoadingStatus: statusQuery.isLoading,
+    config: configQuery.data,
+    lists: listsQuery.data?.lists ?? [],
+    customEntries: customQuery.data?.customEntries ?? [],
+    suggestedLists: suggestedQuery.data?.lists ?? [],
+    updateConfig: updateConfigMutation.mutateAsync,
+    isUpdatingConfig: updateConfigMutation.isPending,
+    addList: addListMutation.mutateAsync,
+    isAddingList: addListMutation.isPending,
+    removeList: removeListMutation.mutateAsync,
+    toggleList: toggleListMutation.mutateAsync,
+    addCustomEntry: addCustomMutation.mutateAsync,
+    removeCustomEntry: removeCustomMutation.mutateAsync,
+    triggerUpdate: triggerUpdateMutation.mutateAsync,
+    isUpdating: triggerUpdateMutation.isPending,
+    uploadList: uploadListMutation.mutateAsync,
+    isUploading: uploadListMutation.isPending,
+    refetch: invalidateAll,
+  };
+}

web/src/router/pages/DnsFilterPage.tsx

@@ -0,0 +1,10 @@
+import { ErrorBoundary } from '../../components';
+import { DnsFilterComponent } from '../../components/DnsFilterComponent';
+
+export function DnsFilterPage() {
+  return (
+    <ErrorBoundary>
+      <DnsFilterComponent />
+    </ErrorBoundary>
+  );
+}

web/src/services/api/dnsfilter.ts

@@ -0,0 +1,94 @@
+import { apiClient } from './client';
+import { getApiBaseUrl } from './config';
+
+export interface QueryStats {
+  totalQueries: number;
+  blockedQueries: number;
+  blockedPercent: number;
+  period: string;
+}
+
+export interface DNSFilterStats {
+  enabled: boolean;
+  totalBlocked: number;
+  listCount: number;
+  enabledLists: number;
+  lastUpdated: string;
+  queryStats?: QueryStats;
+}
+
+export interface DNSFilterConfig {
+  enabled: boolean;
+  intervalHours: number;
+}
+
+export interface Blocklist {
+  id: string;
+  url?: string;
+  name: string;
+  enabled: boolean;
+  entryCount: number;
+  lastUpdated: string;
+  lastError?: string;
+}
+
+export interface CustomEntry {
+  domain: string;
+  type: 'allow' | 'block';
+}
+
+export const dnsFilterApi = {
+  getStatus: () =>
+    apiClient.get<DNSFilterStats>('/api/v1/dns-filter/status'),
+
+  getConfig: () =>
+    apiClient.get<DNSFilterConfig>('/api/v1/dns-filter/config'),
+
+  updateConfig: (data: Partial<DNSFilterConfig>) =>
+    apiClient.put<{ message: string }>('/api/v1/dns-filter/config', data),
+
+  getLists: () =>
+    apiClient.get<{ lists: Blocklist[] }>('/api/v1/dns-filter/lists'),
+
+  addList: (data: { url: string; name: string }) =>
+    apiClient.post<{ message: string }>('/api/v1/dns-filter/lists', data),
+
+  removeList: (id: string) =>
+    apiClient.delete<{ message: string }>(`/api/v1/dns-filter/lists/${id}`),
+
+  toggleList: (id: string, enabled: boolean) =>
+    apiClient.put<{ message: string }>(`/api/v1/dns-filter/lists/${id}/toggle`, { enabled }),
+
+  getCustomEntries: () =>
+    apiClient.get<{ customEntries: CustomEntry[] }>('/api/v1/dns-filter/custom'),
+
+  setCustomEntry: (entry: CustomEntry) =>
+    apiClient.post<{ message: string }>('/api/v1/dns-filter/custom', entry),
+
+  removeCustomEntry: (domain: string) =>
+    apiClient.delete<{ message: string }>(`/api/v1/dns-filter/custom/${domain}`),
+
+  triggerUpdate: () =>
+    apiClient.post<{ message: string }>('/api/v1/dns-filter/update'),
+
+  getSuggested: () =>
+    apiClient.get<{ lists: Blocklist[] }>('/api/v1/dns-filter/lists/suggested'),
+
+  uploadList: async (name: string, file: File): Promise<{ id: string; message: string }> => {
+    const formData = new FormData();
+    formData.append('name', name);
+    formData.append('file', file);
+
+    const response = await fetch(`${getApiBaseUrl()}/api/v1/dns-filter/lists/upload`, {
+      method: 'POST',
+      body: formData,
+    });
+
+    if (!response.ok) {
+      const errorData = await response.json().catch(() => ({}));
+      throw new Error(errorData.error || `HTTP ${response.status}`);
+    }
+
+    return response.json();
+  },
+};