diff --git a/cmd/greywall/main.go b/cmd/greywall/main.go
index 20f1315..56e7d29 100644
--- a/cmd/greywall/main.go
+++ b/cmd/greywall/main.go
@@ -233,13 +233,15 @@ func runCommand(cmd *cobra.Command, args []string) error {
 
 	// GreyHaven defaults: when no proxy or DNS is configured (neither via CLI
 	// nor config file), use the standard GreyHaven infrastructure ports.
-	if cfg.Network.ProxyURL == "" {
+	// Skip GreyHaven proxy default when domain filtering is configured —
+	// the filtering proxy handles outbound instead.
+	if cfg.Network.ProxyURL == "" && !cfg.Network.HasDomainFiltering() {
 		cfg.Network.ProxyURL = "socks5://localhost:42052"
 		if debug {
 			fmt.Fprintf(os.Stderr, "[greywall] Defaulting proxy to socks5://localhost:42052\n")
 		}
 	}
-	if cfg.Network.DnsAddr == "" {
+	if cfg.Network.DnsAddr == "" && !cfg.Network.HasDomainFiltering() {
 		cfg.Network.DnsAddr = "localhost:42053"
 		if debug {
 			fmt.Fprintf(os.Stderr, "[greywall] Defaulting DNS to localhost:42053\n")
diff --git a/internal/config/config.go b/internal/config/config.go
index 352482c..a57fe2b 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -26,8 +26,10 @@ type Config struct {
 
 // NetworkConfig defines network restrictions.
 type NetworkConfig struct {
-	ProxyURL            string   `json:"proxyUrl,omitempty"` // External SOCKS5 proxy (e.g. socks5://host:1080)
-	DnsAddr             string   `json:"dnsAddr,omitempty"`  // DNS server address on host (e.g. localhost:3153)
+	ProxyURL            string   `json:"proxyUrl,omitempty"`       // External SOCKS5 proxy (e.g. socks5://host:1080)
+	DnsAddr             string   `json:"dnsAddr,omitempty"`        // DNS server address on host (e.g. localhost:3153)
+	AllowedDomains      []string `json:"allowedDomains,omitempty"` // Domains to allow outbound connections to (supports wildcards)
+	DeniedDomains       []string `json:"deniedDomains,omitempty"`  // Domains to deny outbound connections to (checked before allowed)
 	AllowUnixSockets    []string `json:"allowUnixSockets,omitempty"`
 	AllowAllUnixSockets bool     `json:"allowAllUnixSockets,omitempty"`
 	AllowLocalBinding   bool     `json:"allowLocalBinding,omitempty"`
@@ -209,6 +211,17 @@ func (c *Config) Validate() error {
 		}
 	}
 
+	for _, domain := range c.Network.AllowedDomains {
+		if err := validateDomainPattern(domain); err != nil {
+			return fmt.Errorf("invalid network.allowedDomains %q: %w", domain, err)
+		}
+	}
+	for _, domain := range c.Network.DeniedDomains {
+		if err := validateDomainPattern(domain); err != nil {
+			return fmt.Errorf("invalid network.deniedDomains %q: %w", domain, err)
+		}
+	}
+
 	if slices.Contains(c.Filesystem.AllowRead, "") {
 		return errors.New("filesystem.allowRead contains empty path")
 	}
@@ -384,6 +397,84 @@ func matchGlob(s, pattern string) bool {
 	return true
 }
 
+// validateDomainPattern validates a domain pattern for allowedDomains/deniedDomains.
+// Rejects patterns with protocol, path, port, or empty strings.
+func validateDomainPattern(pattern string) error {
+	if pattern == "" {
+		return errors.New("empty domain pattern")
+	}
+
+	// Allow wildcard-all
+	if pattern == "*" {
+		return nil
+	}
+
+	// Reject patterns with protocol
+	if strings.Contains(pattern, "://") {
+		return errors.New("domain pattern cannot contain protocol (remove http:// or https://)")
+	}
+
+	// Reject patterns with path
+	if strings.Contains(pattern, "/") {
+		return errors.New("domain pattern cannot contain path")
+	}
+
+	// Reject patterns with port
+	if strings.Contains(pattern, ":") {
+		return errors.New("domain pattern cannot contain port")
+	}
+
+	// Reject patterns with @
+	if strings.Contains(pattern, "@") {
+		return errors.New("domain pattern cannot contain username")
+	}
+
+	return nil
+}
+
+// IsDomainAllowed checks if a hostname is allowed by the domain filtering rules.
+// Strips port from hostname. Deny rules are checked first (deny wins).
+// If AllowedDomains is set, the domain must match at least one allowed pattern.
+// If only DeniedDomains is set, all domains except denied ones are allowed.
+func (n *NetworkConfig) IsDomainAllowed(hostname string) bool {
+	// Strip port if present
+	if host, _, found := strings.Cut(hostname, ":"); found {
+		hostname = host
+	}
+
+	// Check denied domains first (deny wins)
+	for _, pattern := range n.DeniedDomains {
+		if MatchesHost(hostname, pattern) {
+			return false
+		}
+	}
+
+	// If no allowed domains configured, allow all (only deny list is active)
+	if len(n.AllowedDomains) == 0 {
+		return true
+	}
+
+	// Check allowed domains
+	for _, pattern := range n.AllowedDomains {
+		if MatchesHost(hostname, pattern) {
+			return true
+		}
+	}
+
+	// Not in allow list
+	return false
+}
+
+// HasDomainFiltering returns true when domain filtering is configured.
+func (n *NetworkConfig) HasDomainFiltering() bool {
+	return len(n.AllowedDomains) > 0 || len(n.DeniedDomains) > 0
+}
+
+// IsWildcardAllow returns true when AllowedDomains contains "*" (allow all).
+func (n *NetworkConfig) IsWildcardAllow() bool {
+	return slices.Contains(n.AllowedDomains, "*")
+}
+
 // Merge combines a base config with an override config.
 // Values in override take precedence. Slice fields are appended (base + override).
 // The Extends field is cleared in the result since inheritance has been resolved.
@@ -411,6 +502,10 @@ func Merge(base, override *Config) *Config {
 			ProxyURL: mergeString(base.Network.ProxyURL, override.Network.ProxyURL),
 			DnsAddr:  mergeString(base.Network.DnsAddr, override.Network.DnsAddr),
 
+			// Append domain slices
+			AllowedDomains: mergeStrings(base.Network.AllowedDomains, override.Network.AllowedDomains),
+			DeniedDomains:  mergeStrings(base.Network.DeniedDomains, override.Network.DeniedDomains),
+
 			// Append slices (base first, then override additions)
 			AllowUnixSockets: mergeStrings(base.Network.AllowUnixSockets, override.Network.AllowUnixSockets),
 
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 58d268c..b213db6 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -668,6 +668,265 @@ func TestMergeSSHConfig(t *testing.T) {
 	})
 }
 
+func TestValidateDomainPattern(t *testing.T) {
+	tests := []struct {
+		name    string
+		pattern string
+		wantErr bool
+	}{
+		// Valid patterns
+		{"simple domain", "example.com", false},
+		{"subdomain", "api.example.com", false},
+		{"wildcard prefix", "*.example.com", false},
+		{"wildcard all", "*", false},
+		{"wildcard middle", "api-*.example.com", false},
+		{"localhost", "localhost", false},
+
+		// Invalid patterns
+		{"empty", "", true},
+		{"with protocol http", "http://example.com", true},
+		{"with protocol https", "https://example.com", true},
+		{"with path", "example.com/path", true},
+		{"with port", "example.com:443", true},
+		{"with username", "user@example.com", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := validateDomainPattern(tt.pattern)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("validateDomainPattern(%q) error = %v, wantErr %v", tt.pattern, err, tt.wantErr)
+			}
+		})
+	}
+}
+
+func TestIsDomainAllowed(t *testing.T) {
+	tests := []struct {
+		name           string
+		allowedDomains []string
+		deniedDomains  []string
+		hostname       string
+		want           bool
+	}{
+		// Allow list only
+		{"allowed exact match", []string{"api.example.com"}, nil, "api.example.com", true},
+		{"allowed wildcard match", []string{"*.example.com"}, nil, "api.example.com", true},
+		{"allowed no match", []string{"api.example.com"}, nil, "other.com", false},
+		{"allowed wildcard all", []string{"*"}, nil, "anything.com", true},
+		{"allowed multiple", []string{"api.example.com", "cdn.example.com"}, nil, "cdn.example.com", true},
+
+		// Deny list only (no allow list = allow all except denied)
+		{"denied only - not denied", nil, []string{"evil.com"}, "good.com", true},
+		{"denied only - denied match", nil, []string{"evil.com"}, "evil.com", false},
+		{"denied only - wildcard deny", nil, []string{"*.evil.com"}, "sub.evil.com", false},
+
+		// Both allow and deny (deny wins)
+		{"deny wins over allow", []string{"*.example.com"}, []string{"secret.example.com"}, "secret.example.com", false},
+		{"allow works when not denied", []string{"*.example.com"}, []string{"secret.example.com"}, "api.example.com", true},
+		{"not in allow after deny check", []string{"*.example.com"}, []string{"evil.com"}, "other.com", false},
+
+		// Port stripping
+		{"strips port", []string{"api.example.com"}, nil, "api.example.com:443", true},
+		{"strips port denied", nil, []string{"evil.com"}, "evil.com:8080", false},
+
+		// Empty allow list = allow all (only deny active)
+		{"empty allow list allows all", nil, nil, "anything.com", true},
+		{"empty both allows all", []string{}, []string{}, "anything.com", true},
+
+		// Case insensitive
+		{"case insensitive", []string{"API.Example.COM"}, nil, "api.example.com", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			nc := &NetworkConfig{
+				AllowedDomains: tt.allowedDomains,
+				DeniedDomains:  tt.deniedDomains,
+			}
+			got := nc.IsDomainAllowed(tt.hostname)
+			if got != tt.want {
+				t.Errorf("IsDomainAllowed(%q) = %v, want %v (allowed=%v, denied=%v)",
+					tt.hostname, got, tt.want, tt.allowedDomains, tt.deniedDomains)
+			}
+		})
+	}
+}
+
+func TestHasDomainFiltering(t *testing.T) {
+	tests := []struct {
+		name           string
+		allowedDomains []string
+		deniedDomains  []string
+		want           bool
+	}{
+		{"no domains", nil, nil, false},
+		{"empty slices", []string{}, []string{}, false},
+		{"allowed only", []string{"example.com"}, nil, true},
+		{"denied only", nil, []string{"evil.com"}, true},
+		{"both", []string{"example.com"}, []string{"evil.com"}, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			nc := &NetworkConfig{
+				AllowedDomains: tt.allowedDomains,
+				DeniedDomains:  tt.deniedDomains,
+			}
+			got := nc.HasDomainFiltering()
+			if got != tt.want {
+				t.Errorf("HasDomainFiltering() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestIsWildcardAllow(t *testing.T) {
+	tests := []struct {
+		name           string
+		allowedDomains []string
+		want           bool
+	}{
+		{"nil", nil, false},
+		{"empty", []string{}, false},
+		{"specific domain", []string{"example.com"}, false},
+		{"wildcard", []string{"*"}, true},
+		{"wildcard among others", []string{"example.com", "*"}, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			nc := &NetworkConfig{AllowedDomains: tt.allowedDomains}
+			got := nc.IsWildcardAllow()
+			if got != tt.want {
+				t.Errorf("IsWildcardAllow() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestConfigValidateDomains(t *testing.T) {
+	tests := []struct {
+		name    string
+		config  Config
+		wantErr bool
+	}{
+		{
+			name: "valid allowed domains",
+			config: Config{
+				Network: NetworkConfig{
+					AllowedDomains: []string{"api.example.com", "*.cdn.example.com"},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "valid denied domains",
+			config: Config{
+				Network: NetworkConfig{
+					DeniedDomains: []string{"evil.com", "*.malware.com"},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "invalid allowed domain with protocol",
+			config: Config{
+				Network: NetworkConfig{
+					AllowedDomains: []string{"https://example.com"},
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: "invalid denied domain with port",
+			config: Config{
+				Network: NetworkConfig{
+					DeniedDomains: []string{"example.com:443"},
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: "invalid allowed domain empty",
+			config: Config{
+				Network: NetworkConfig{
+					AllowedDomains: []string{""},
+				},
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := tt.config.Validate()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Config.Validate() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}
+
+func TestMergeDomainConfig(t *testing.T) {
+	t.Run("merge allowed domains", func(t *testing.T) {
+		base := &Config{
+			Network: NetworkConfig{
+				AllowedDomains: []string{"api.example.com"},
+			},
+		}
+		override := &Config{
+			Network: NetworkConfig{
+				AllowedDomains: []string{"cdn.example.com"},
+			},
+		}
+		result := Merge(base, override)
+
+		if len(result.Network.AllowedDomains) != 2 {
+			t.Errorf("expected 2 allowed domains, got %d: %v",
+				len(result.Network.AllowedDomains), result.Network.AllowedDomains)
+		}
+	})
+
+	t.Run("merge denied domains", func(t *testing.T) {
+		base := &Config{
+			Network: NetworkConfig{
+				DeniedDomains: []string{"evil.com"},
+			},
+		}
+		override := &Config{
+			Network: NetworkConfig{
+				DeniedDomains: []string{"malware.com"},
+			},
+		}
+		result := Merge(base, override)
+
+		if len(result.Network.DeniedDomains) != 2 {
+			t.Errorf("expected 2 denied domains, got %d: %v",
+				len(result.Network.DeniedDomains), result.Network.DeniedDomains)
+		}
+	})
+
+	t.Run("merge deduplicates domains", func(t *testing.T) {
+		base := &Config{
+			Network: NetworkConfig{
+				AllowedDomains: []string{"api.example.com"},
+			},
+		}
+		override := &Config{
+			Network: NetworkConfig{
+				AllowedDomains: []string{"api.example.com"},
+			},
+		}
+		result := Merge(base, override)
+
+		if len(result.Network.AllowedDomains) != 1 {
+			t.Errorf("expected 1 allowed domain (deduped), got %d: %v",
+				len(result.Network.AllowedDomains), result.Network.AllowedDomains)
+		}
+	})
+}
+
 func TestValidateProxyURL(t *testing.T) {
 	tests := []struct {
 		name    string
diff --git a/internal/sandbox/linux.go b/internal/sandbox/linux.go
index 23be2c2..4b9359e 100644
--- a/internal/sandbox/linux.go
+++ b/internal/sandbox/linux.go
@@ -594,8 +594,8 @@ func isSystemMountPoint(path string) bool {
 
 // WrapCommandLinux wraps a command with Linux bubblewrap sandbox.
 // It uses available security features (Landlock, seccomp) with graceful fallback.
-func WrapCommandLinux(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, debug bool) (string, error) {
-	return WrapCommandLinuxWithOptions(cfg, command, proxyBridge, dnsBridge, reverseBridge, tun2socksPath, LinuxSandboxOptions{
+func WrapCommandLinux(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, filterProxy *FilteringProxy, debug bool) (string, error) {
+	return WrapCommandLinuxWithOptions(cfg, command, proxyBridge, dnsBridge, reverseBridge, tun2socksPath, filterProxy, LinuxSandboxOptions{
 		UseLandlock: true, // Enabled by default, will fall back if not available
 		UseSeccomp:  true, // Enabled by default
 		UseEBPF:     true, // Enabled by default if available
@@ -604,7 +604,7 @@ func WrapCommandLinux(cfg *config.Config, command string, proxyBridge *ProxyBrid
 }
 
 // WrapCommandLinuxWithOptions wraps a command with configurable sandbox options.
-func WrapCommandLinuxWithOptions(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, opts LinuxSandboxOptions) (string, error) {
+func WrapCommandLinuxWithOptions(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, filterProxy *FilteringProxy, opts LinuxSandboxOptions) (string, error) {
 	if _, err := exec.LookPath("bwrap"); err != nil {
 		return "", fmt.Errorf("bubblewrap (bwrap) is required on Linux but not found: %w", err)
 	}
@@ -636,11 +636,18 @@ func WrapCommandLinuxWithOptions(cfg *config.Config, command string, proxyBridge
 	bwrapArgs = append(bwrapArgs, "--die-with-parent")
 
 	// Always use --unshare-net when available (network namespace isolation)
-	// Inside the namespace, tun2socks will provide transparent proxy access
-	if features.CanUnshareNet {
+	// Inside the namespace, tun2socks will provide transparent proxy access.
+	// Skip network namespace when domain filtering with wildcard allow is active
+	// (the filtering proxy handles domain enforcement via env vars).
+	skipUnshareNet := filterProxy != nil && cfg != nil && cfg.Network.IsWildcardAllow()
+	if features.CanUnshareNet && !skipUnshareNet {
 		bwrapArgs = append(bwrapArgs, "--unshare-net") // Network namespace isolation
 	} else if opts.Debug {
-		fmt.Fprintf(os.Stderr, "[greywall:linux] Skipping --unshare-net (network namespace unavailable in this environment)\n")
+		if skipUnshareNet {
+			fmt.Fprintf(os.Stderr, "[greywall:linux] Skipping --unshare-net (wildcard allow with domain filtering)\n")
+		} else {
+			fmt.Fprintf(os.Stderr, "[greywall:linux] Skipping --unshare-net (network namespace unavailable in this environment)\n")
+		}
 	}
 
 	bwrapArgs = append(bwrapArgs, "--unshare-pid") // PID namespace isolation
@@ -1042,6 +1049,23 @@ export no_proxy=localhost,127.0.0.1
 `, proxyBridge.SocketPath))
 	}
 
+	// Set up domain filtering proxy env vars inside the sandbox.
+	// When filterProxy is active, skip tun2socks and use env-var-based proxying
+	// through a socat bridge to the host-side filtering proxy.
+	if filterProxy != nil && proxyBridge == nil {
+		filterProxyAddr := filterProxy.Addr()
+		innerScript.WriteString(fmt.Sprintf(`
+# Domain filtering proxy: bridge to host-side filtering proxy
+export HTTP_PROXY=http://%s
+export HTTPS_PROXY=http://%s
+export http_proxy=http://%s
+export https_proxy=http://%s
+export NO_PROXY=localhost,127.0.0.1
+export no_proxy=localhost,127.0.0.1
+
+`, filterProxyAddr, filterProxyAddr, filterProxyAddr, filterProxyAddr))
+	}
+
 	// Set up reverse (inbound) socat listeners inside the sandbox
 	if reverseBridge != nil && len(reverseBridge.Ports) > 0 {
 		innerScript.WriteString("\n# Start reverse bridge listeners for inbound connections\n")
diff --git a/internal/sandbox/linux_stub.go b/internal/sandbox/linux_stub.go
index 713e72f..ad86da1 100644
--- a/internal/sandbox/linux_stub.go
+++ b/internal/sandbox/linux_stub.go
@@ -63,12 +63,12 @@ func NewReverseBridge(ports []int, debug bool) (*ReverseBridge, error) {
 func (b *ReverseBridge) Cleanup() {}
 
 // WrapCommandLinux returns an error on non-Linux platforms.
-func WrapCommandLinux(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, debug bool) (string, error) {
+func WrapCommandLinux(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, filterProxy *FilteringProxy, debug bool) (string, error) {
 	return "", fmt.Errorf("Linux sandbox not available on this platform")
 }
 
 // WrapCommandLinuxWithOptions returns an error on non-Linux platforms.
-func WrapCommandLinuxWithOptions(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, opts LinuxSandboxOptions) (string, error) {
+func WrapCommandLinuxWithOptions(cfg *config.Config, command string, proxyBridge *ProxyBridge, dnsBridge *DnsBridge, reverseBridge *ReverseBridge, tun2socksPath string, filterProxy *FilteringProxy, opts LinuxSandboxOptions) (string, error) {
 	return "", fmt.Errorf("Linux sandbox not available on this platform")
 }
 
diff --git a/internal/sandbox/macos.go b/internal/sandbox/macos.go
index c13910a..7decc67 100644
--- a/internal/sandbox/macos.go
+++ b/internal/sandbox/macos.go
@@ -631,7 +631,7 @@ func GenerateSandboxProfile(params MacOSSandboxParams) string {
 }
 
 // WrapCommandMacOS wraps a command with macOS sandbox restrictions.
-func WrapCommandMacOS(cfg *config.Config, command string, exposedPorts []int, debug bool) (string, error) {
+func WrapCommandMacOS(cfg *config.Config, command string, exposedPorts []int, filterProxy *FilteringProxy, debug bool) (string, error) {
 	cwd, _ := os.Getwd()
 
 	// Build allow paths: default + configured
@@ -650,7 +650,12 @@ func WrapCommandMacOS(cfg *config.Config, command string, exposedPorts []int, de
 
 	// Parse proxy URL for network rules
 	var proxyHost, proxyPort string
-	if cfg.Network.ProxyURL != "" {
+	if filterProxy != nil {
+		// Domain filtering proxy: point at the local filtering proxy.
+		// Seatbelt only accepts "localhost" or "*" in (remote ip ...) filters.
+		proxyHost = "localhost"
+		proxyPort = filterProxy.Port()
+	} else if cfg.Network.ProxyURL != "" {
 		if u, err := url.Parse(cfg.Network.ProxyURL); err == nil {
 			proxyHost = u.Hostname()
 			proxyPort = u.Port()
@@ -659,7 +664,11 @@ func WrapCommandMacOS(cfg *config.Config, command string, exposedPorts []int, de
 
 	// Restrict network unless proxy is configured to an external host
 	// If no proxy: block all outbound. If proxy: allow outbound only to proxy.
+	// When wildcard allow with domain filtering, allow direct outbound (proxy enforces via env vars)
 	needsNetworkRestriction := true
+	if filterProxy != nil && cfg.Network.IsWildcardAllow() {
+		needsNetworkRestriction = false
+	}
 
 	params := MacOSSandboxParams{
 		Command:                 command,
@@ -700,7 +709,12 @@ func WrapCommandMacOS(cfg *config.Config, command string, exposedPorts []int, de
 		return "", fmt.Errorf("shell %q not found: %w", shell, err)
 	}
 
-	proxyEnvs := GenerateProxyEnvVars(cfg.Network.ProxyURL)
+	var proxyEnvs []string
+	if filterProxy != nil {
+		proxyEnvs = GenerateHTTPProxyEnvVars(fmt.Sprintf("http://127.0.0.1:%s", filterProxy.Port()))
+	} else {
+		proxyEnvs = GenerateProxyEnvVars(cfg.Network.ProxyURL)
+	}
 
 	// Build the command
 	// env VAR1=val1 VAR2=val2 sandbox-exec -p 'profile' shell -c 'command'
diff --git a/internal/sandbox/manager.go b/internal/sandbox/manager.go
index 8ae7ce4..a3ca801 100644
--- a/internal/sandbox/manager.go
+++ b/internal/sandbox/manager.go
@@ -14,6 +14,7 @@ type Manager struct {
 	proxyBridge   *ProxyBridge
 	dnsBridge     *DnsBridge
 	reverseBridge *ReverseBridge
+	filterProxy   *FilteringProxy
 	tun2socksPath string // path to extracted tun2socks binary on host
 	exposedPorts  []int
 	debug         bool
@@ -118,6 +119,36 @@ func (m *Manager) Initialize() error {
 		}
 	}
 
+	// Start domain filtering proxy if allowedDomains/deniedDomains are configured
+	if m.config.Network.HasDomainFiltering() {
+		fp, err := NewFilteringProxy(&m.config.Network, m.debug)
+		if err != nil {
+			// Clean up any bridges that were already started
+			if m.reverseBridge != nil {
+				m.reverseBridge.Cleanup()
+			}
+			if m.dnsBridge != nil {
+				m.dnsBridge.Cleanup()
+			}
+			if m.proxyBridge != nil {
+				m.proxyBridge.Cleanup()
+			}
+			if m.tun2socksPath != "" {
+				_ = os.Remove(m.tun2socksPath)
+			}
+			return fmt.Errorf("failed to start filtering proxy: %w", err)
+		}
+		m.filterProxy = fp
+		m.logDebug("Domain filtering proxy started on %s", fp.Addr())
+
+		// Write Node.js proxy bootstrap script so fetch() honors HTTP_PROXY
+		if bootstrapPath, err := WriteNodeProxyBootstrap(); err != nil {
+			m.logDebug("Warning: failed to write Node.js proxy bootstrap: %v", err)
+		} else {
+			m.logDebug("Node.js proxy bootstrap written to %s", bootstrapPath)
+		}
+	}
+
 	m.initialized = true
 	if m.config.Network.ProxyURL != "" {
 		dnsInfo := "none"
@@ -148,12 +179,12 @@ func (m *Manager) WrapCommand(command string) (string, error) {
 	plat := platform.Detect()
 	switch plat {
 	case platform.MacOS:
-		return WrapCommandMacOS(m.config, command, m.exposedPorts, m.debug)
+		return WrapCommandMacOS(m.config, command, m.exposedPorts, m.filterProxy, m.debug)
 	case platform.Linux:
 		if m.learning {
 			return m.wrapCommandLearning(command)
 		}
-		return WrapCommandLinux(m.config, command, m.proxyBridge, m.dnsBridge, m.reverseBridge, m.tun2socksPath, m.debug)
+		return WrapCommandLinux(m.config, command, m.proxyBridge, m.dnsBridge, m.reverseBridge, m.tun2socksPath, m.filterProxy, m.debug)
 	default:
 		return "", fmt.Errorf("unsupported platform: %s", plat)
 	}
@@ -171,7 +202,7 @@ func (m *Manager) wrapCommandLearning(command string) (string, error) {
 
 	m.logDebug("Strace log file: %s", m.straceLogPath)
 
-	return WrapCommandLinuxWithOptions(m.config, command, m.proxyBridge, m.dnsBridge, m.reverseBridge, m.tun2socksPath, LinuxSandboxOptions{
+	return WrapCommandLinuxWithOptions(m.config, command, m.proxyBridge, m.dnsBridge, m.reverseBridge, m.tun2socksPath, m.filterProxy, LinuxSandboxOptions{
 		UseLandlock:   false, // Disabled: seccomp blocks ptrace which strace needs
 		UseSeccomp:    false, // Disabled: conflicts with strace
 		UseEBPF:       false,
@@ -201,6 +232,9 @@ func (m *Manager) GenerateLearnedTemplate(cmdName string) (string, error) {
 
 // Cleanup stops the proxies and cleans up resources.
 func (m *Manager) Cleanup() {
+	if m.filterProxy != nil {
+		m.filterProxy.Shutdown()
+	}
 	if m.reverseBridge != nil {
 		m.reverseBridge.Cleanup()
 	}
diff --git a/internal/sandbox/monitor.go b/internal/sandbox/monitor.go
index 5cc33a8..1eab6e9 100644
--- a/internal/sandbox/monitor.go
+++ b/internal/sandbox/monitor.go
@@ -138,9 +138,9 @@ func parseViolation(line string) string {
 	timestamp := time.Now().Format("15:04:05")
 
 	if details != "" {
-		return fmt.Sprintf("[greywall:logstream] %s ✗ %s %s (%s:%s)", timestamp, operation, details, process, pid)
+		return fmt.Sprintf("\033[31m[greywall:logstream] %s ✗ %s %s (%s:%s)\033[0m", timestamp, operation, details, process, pid)
 	}
-	return fmt.Sprintf("[greywall:logstream] %s ✗ %s (%s:%s)", timestamp, operation, process, pid)
+	return fmt.Sprintf("\033[31m[greywall:logstream] %s ✗ %s (%s:%s)\033[0m", timestamp, operation, process, pid)
 }
 
 // shouldShowViolation returns true if this violation type should be displayed.
diff --git a/internal/sandbox/proxy.go b/internal/sandbox/proxy.go
new file mode 100644
index 0000000..4a9f966
--- /dev/null
+++ b/internal/sandbox/proxy.go
@@ -0,0 +1,245 @@
+package sandbox
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"gitea.app.monadical.io/monadical/greywall/internal/config"
+)
+
+// FilteringProxy is an HTTP CONNECT proxy that filters outbound connections by domain.
+// It runs on the host and is the only outbound target the sandbox allows.
+type FilteringProxy struct {
+	listener net.Listener
+	server   *http.Server
+	network  *config.NetworkConfig
+	debug    bool
+	mu       sync.Mutex
+	closed   bool
+}
+
+// NewFilteringProxy creates and starts a new domain-filtering HTTP proxy.
+// It listens on 127.0.0.1 with a random available port.
+func NewFilteringProxy(network *config.NetworkConfig, debug bool) (*FilteringProxy, error) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return nil, fmt.Errorf("failed to listen: %w", err)
+	}
+
+	fp := &FilteringProxy{
+		listener: listener,
+		network:  network,
+		debug:    debug,
+	}
+
+	fp.server = &http.Server{
+		Handler:           http.HandlerFunc(fp.serveHTTP),
+		ReadHeaderTimeout: 30 * time.Second,
+	}
+
+	go func() {
+		if err := fp.server.Serve(listener); err != nil && err != http.ErrServerClosed {
+			fp.logDebug("Proxy server error: %v", err)
+		}
+	}()
+
+	if debug {
+		fmt.Fprintf(os.Stderr, "[greywall:proxy] Filtering proxy started on %s\n", listener.Addr().String())
+	}
+
+	return fp, nil
+}
+
+func (fp *FilteringProxy) serveHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method == http.MethodConnect {
+		fp.handleConnect(w, r)
+	} else if r.Method == http.MethodGet && r.URL.Path == "/__greywall_dns" {
+		fp.handleDNS(w, r)
+	} else {
+		fp.handleHTTP(w, r)
+	}
+}
+
+// handleDNS resolves a hostname and returns the IP addresses as JSON.
+// Used by the Node.js bootstrap to patch dns.lookup inside the sandbox.
+func (fp *FilteringProxy) handleDNS(w http.ResponseWriter, r *http.Request) {
+	host := r.URL.Query().Get("host")
+	if host == "" {
+		w.Header().Set("Content-Type", "application/json")
+		http.Error(w, `{"error":"missing host parameter"}`, http.StatusBadRequest)
+		return
+	}
+
+	if !fp.network.IsDomainAllowed(host) {
+		fp.logDenied(host)
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusForbidden)
+		fmt.Fprintf(w, `{"error":"domain denied: %s"}`, host)
+		return
+	}
+
+	addrs, err := net.LookupHost(host)
+	if err != nil {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusNotFound)
+		fmt.Fprintf(w, `{"error":"%s"}`, err.Error())
+		return
+	}
+
+	type addrEntry struct {
+		Address string `json:"address"`
+		Family  int    `json:"family"`
+	}
+
+	var entries []addrEntry
+	for _, addr := range addrs {
+		family := 4
+		if strings.Contains(addr, ":") {
+			family = 6
+		}
+		entries = append(entries, addrEntry{Address: addr, Family: family})
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(map[string]interface{}{
+		"addresses": entries,
+	})
+}
+
+func (fp *FilteringProxy) handleConnect(w http.ResponseWriter, r *http.Request) {
+	host := extractHost(r.Host)
+
+	if !fp.network.IsDomainAllowed(host) {
+		fp.logDenied(host)
+		http.Error(w, fmt.Sprintf("[greywall] domain denied: %s", host), http.StatusForbidden)
+		return
+	}
+
+	// Dial the target
+	target := r.Host
+	if !strings.Contains(target, ":") {
+		target = target + ":443"
+	}
+
+	destConn, err := net.DialTimeout("tcp", target, 10*time.Second)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("[greywall] failed to connect to %s: %v", target, err), http.StatusBadGateway)
+		return
+	}
+
+	// Hijack the client connection
+	hijacker, ok := w.(http.Hijacker)
+	if !ok {
+		destConn.Close()
+		http.Error(w, "[greywall] hijacking not supported", http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+
+	clientConn, _, err := hijacker.Hijack()
+	if err != nil {
+		destConn.Close()
+		return
+	}
+
+	// Bidirectional copy
+	go func() {
+		defer destConn.Close()
+		defer clientConn.Close()
+		_, _ = io.Copy(destConn, clientConn)
+	}()
+	go func() {
+		defer destConn.Close()
+		defer clientConn.Close()
+		_, _ = io.Copy(clientConn, destConn)
+	}()
+}
+
+func (fp *FilteringProxy) handleHTTP(w http.ResponseWriter, r *http.Request) {
+	host := extractHost(r.Host)
+
+	if !fp.network.IsDomainAllowed(host) {
+		fp.logDenied(host)
+		http.Error(w, fmt.Sprintf("[greywall] domain denied: %s", host), http.StatusForbidden)
+		return
+	}
+
+	// Forward the request
+	r.RequestURI = ""
+
+	resp, err := http.DefaultTransport.RoundTrip(r)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("[greywall] failed to forward request: %v", err), http.StatusBadGateway)
+		return
+	}
+	defer resp.Body.Close()
+
+	// Copy response headers
+	for key, values := range resp.Header {
+		for _, value := range values {
+			w.Header().Add(key, value)
+		}
+	}
+	w.WriteHeader(resp.StatusCode)
+	_, _ = io.Copy(w, resp.Body)
+}
+
+// Addr returns the listener address as a string (e.g. "127.0.0.1:12345").
+func (fp *FilteringProxy) Addr() string {
+	return fp.listener.Addr().String()
+}
+
+// Port returns the listener port as a string.
+func (fp *FilteringProxy) Port() string {
+	_, port, _ := net.SplitHostPort(fp.listener.Addr().String())
+	return port
+}
+
+// Shutdown gracefully stops the proxy.
+func (fp *FilteringProxy) Shutdown() {
+	fp.mu.Lock()
+	defer fp.mu.Unlock()
+
+	if fp.closed {
+		return
+	}
+	fp.closed = true
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	_ = fp.server.Shutdown(ctx)
+
+	if fp.debug {
+		fmt.Fprintf(os.Stderr, "[greywall:proxy] Filtering proxy stopped\n")
+	}
+}
+
+func (fp *FilteringProxy) logDenied(host string) {
+	fmt.Fprintf(os.Stderr, "\033[31m[greywall:proxy] domain denied: %s\033[0m\n", host)
+}
+
+func (fp *FilteringProxy) logDebug(format string, args ...interface{}) {
+	if fp.debug {
+		fmt.Fprintf(os.Stderr, "[greywall:proxy] "+format+"\n", args...)
+	}
+}
+
+// extractHost extracts the hostname from a host:port string, stripping the port.
+func extractHost(hostport string) string {
+	host, _, err := net.SplitHostPort(hostport)
+	if err != nil {
+		// No port present
+		return hostport
+	}
+	return host
+}
diff --git a/internal/sandbox/proxy_test.go b/internal/sandbox/proxy_test.go
new file mode 100644
index 0000000..b1a317c
--- /dev/null
+++ b/internal/sandbox/proxy_test.go
@@ -0,0 +1,193 @@
+package sandbox
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"testing"
+	"time"
+
+	"gitea.app.monadical.io/monadical/greywall/internal/config"
+)
+
+func TestFilteringProxy_AllowedDomain(t *testing.T) {
+	nc := &config.NetworkConfig{
+		AllowedDomains: []string{"httpbin.org"},
+	}
+
+	fp, err := NewFilteringProxy(nc, false)
+	if err != nil {
+		t.Fatalf("NewFilteringProxy() error = %v", err)
+	}
+	defer fp.Shutdown()
+
+	if fp.Port() == "" {
+		t.Fatal("expected non-empty port")
+	}
+	if fp.Addr() == "" {
+		t.Fatal("expected non-empty addr")
+	}
+}
+
+func TestFilteringProxy_DeniedDomain_HTTP(t *testing.T) {
+	nc := &config.NetworkConfig{
+		AllowedDomains: []string{"allowed.example.com"},
+	}
+
+	fp, err := NewFilteringProxy(nc, false)
+	if err != nil {
+		t.Fatalf("NewFilteringProxy() error = %v", err)
+	}
+	defer fp.Shutdown()
+
+	// Make a plain HTTP request to a denied domain through the proxy
+	proxyURL, _ := url.Parse(fmt.Sprintf("http://%s", fp.Addr()))
+	client := &http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyURL(proxyURL),
+		},
+		Timeout: 5 * time.Second,
+	}
+
+	resp, err := client.Get("http://denied.example.com/test")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusForbidden {
+		body, _ := io.ReadAll(resp.Body)
+		t.Errorf("expected 403 Forbidden, got %d: %s", resp.StatusCode, string(body))
+	}
+}
+
+func TestFilteringProxy_DeniedDomain_CONNECT(t *testing.T) {
+	nc := &config.NetworkConfig{
+		AllowedDomains: []string{"allowed.example.com"},
+	}
+
+	fp, err := NewFilteringProxy(nc, false)
+	if err != nil {
+		t.Fatalf("NewFilteringProxy() error = %v", err)
+	}
+	defer fp.Shutdown()
+
+	// Make a CONNECT request to a denied domain
+	proxyURL, _ := url.Parse(fmt.Sprintf("http://%s", fp.Addr()))
+	client := &http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyURL(proxyURL),
+		},
+		Timeout: 5 * time.Second,
+	}
+
+	// HTTPS triggers CONNECT method through the proxy
+	_, err = client.Get("https://denied.example.com/test")
+	if err == nil {
+		t.Error("expected error for denied CONNECT, got nil")
+	}
+	// The error should indicate the proxy rejected the connection (403)
+}
+
+func TestFilteringProxy_DenyList_Only(t *testing.T) {
+	nc := &config.NetworkConfig{
+		DeniedDomains: []string{"evil.com"},
+	}
+
+	fp, err := NewFilteringProxy(nc, false)
+	if err != nil {
+		t.Fatalf("NewFilteringProxy() error = %v", err)
+	}
+	defer fp.Shutdown()
+
+	proxyURL, _ := url.Parse(fmt.Sprintf("http://%s", fp.Addr()))
+	client := &http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyURL(proxyURL),
+		},
+		Timeout: 5 * time.Second,
+	}
+
+	// Denied domain should be blocked
+	resp, err := client.Get("http://evil.com/test")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusForbidden {
+		t.Errorf("expected 403 for denied domain, got %d", resp.StatusCode)
+	}
+}
+
+func TestFilteringProxy_WildcardAllow(t *testing.T) {
+	nc := &config.NetworkConfig{
+		AllowedDomains: []string{"*"},
+		DeniedDomains:  []string{"evil.com"},
+	}
+
+	fp, err := NewFilteringProxy(nc, false)
+	if err != nil {
+		t.Fatalf("NewFilteringProxy() error = %v", err)
+	}
+	defer fp.Shutdown()
+
+	proxyURL, _ := url.Parse(fmt.Sprintf("http://%s", fp.Addr()))
+	client := &http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyURL(proxyURL),
+		},
+		Timeout: 5 * time.Second,
+	}
+
+	// Denied domain should still be blocked even with wildcard allow
+	resp, err := client.Get("http://evil.com/test")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusForbidden {
+		t.Errorf("expected 403 for denied domain with wildcard allow, got %d", resp.StatusCode)
+	}
+}
+
+func TestFilteringProxy_Shutdown(t *testing.T) {
+	nc := &config.NetworkConfig{
+		AllowedDomains: []string{"example.com"},
+	}
+
+	fp, err := NewFilteringProxy(nc, false)
+	if err != nil {
+		t.Fatalf("NewFilteringProxy() error = %v", err)
+	}
+
+	// Shutdown should not panic
+	fp.Shutdown()
+
+	// Double shutdown should not panic
+	fp.Shutdown()
+}
+
+func TestExtractHost(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string
+	}{
+		{"example.com:443", "example.com"},
+		{"example.com:80", "example.com"},
+		{"example.com", "example.com"},
+		{"127.0.0.1:8080", "127.0.0.1"},
+		{"[::1]:443", "::1"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			got := extractHost(tt.input)
+			if got != tt.want {
+				t.Errorf("extractHost(%q) = %q, want %q", tt.input, got, tt.want)
+			}
+		})
+	}
+}
diff --git a/internal/sandbox/utils.go b/internal/sandbox/utils.go
index 4b888cd..ed8fe40 100644
--- a/internal/sandbox/utils.go
+++ b/internal/sandbox/utils.go
@@ -86,6 +86,353 @@ func GenerateProxyEnvVars(proxyURL string) []string {
 	return envVars
 }
 
+// GenerateHTTPProxyEnvVars creates environment variables for an HTTP proxy.
+// Used when domain filtering is active (HTTP CONNECT proxy, not SOCKS5).
+func GenerateHTTPProxyEnvVars(httpProxyURL string) []string {
+	envVars := []string{
+		"GREYWALL_SANDBOX=1",
+		"TMPDIR=/tmp/greywall",
+	}
+
+	if httpProxyURL == "" {
+		return envVars
+	}
+
+	// NO_PROXY for localhost and private networks
+	noProxy := strings.Join([]string{
+		"localhost",
+		"127.0.0.1",
+		"::1",
+		"*.local",
+		".local",
+		"169.254.0.0/16",
+		"10.0.0.0/8",
+		"172.16.0.0/12",
+		"192.168.0.0/16",
+	}, ",")
+
+	envVars = append(envVars,
+		"NO_PROXY="+noProxy,
+		"no_proxy="+noProxy,
+		"HTTP_PROXY="+httpProxyURL,
+		"HTTPS_PROXY="+httpProxyURL,
+		"http_proxy="+httpProxyURL,
+		"https_proxy="+httpProxyURL,
+	)
+
+	// Inject Node.js proxy bootstrap so fetch() honors HTTP_PROXY.
+	// Appends to existing NODE_OPTIONS if set.
+	nodeOpts := "--require " + nodeProxyBootstrapPath
+	if existing := os.Getenv("NODE_OPTIONS"); existing != "" {
+		nodeOpts = existing + " " + nodeOpts
+	}
+	envVars = append(envVars, "NODE_OPTIONS="+nodeOpts)
+
+	return envVars
+}
+
+// nodeProxyBootstrapJS is the Node.js bootstrap script that makes both
+// fetch() and http/https.request() respect HTTP_PROXY/HTTPS_PROXY env vars.
+//
+// Two mechanisms are needed because Node.js has two separate HTTP stacks:
+// 1. fetch() — powered by undici, patched via EnvHttpProxyAgent
+// 2. http.request()/https.request() — built-in modules, patched via
+//    Agent.prototype.createConnection on BOTH http.Agent and https.Agent.
+//    This patches the prototype so ALL agent instances (including custom ones
+//    created by libraries like node-fetch, axios, got, etc.) tunnel through
+//    the proxy — not just globalAgent.
+//
+// The undici setup tries multiple strategies to find the module:
+// 1. require('undici') from CWD
+// 2. createRequire from the main script's path (finds it in the app's node_modules)
+const nodeProxyBootstrapJS = `'use strict';
+(function() {
+  var proxyUrl = process.env.HTTPS_PROXY || process.env.HTTP_PROXY ||
+                 process.env.https_proxy || process.env.http_proxy;
+  if (!proxyUrl) return;
+
+  // --- Part 1: Patch fetch() via undici EnvHttpProxyAgent ---
+  // Strategy: set global dispatcher AND wrap globalThis.fetch to force proxy.
+  // This prevents openclaw or other code from overriding the global dispatcher.
+  var undiciModule = null;
+  var proxyAgent = null;
+
+  function tryGetUndici(undici) {
+    if (undici && typeof undici.EnvHttpProxyAgent === 'function' &&
+        typeof undici.setGlobalDispatcher === 'function') {
+      return undici;
+    }
+    return null;
+  }
+
+  try { undiciModule = tryGetUndici(require('undici')); } catch (e) {}
+
+  if (!undiciModule) {
+    try {
+      var mainScript = process.argv[1];
+      if (mainScript) {
+        var createRequire = require('module').createRequire;
+        var requireFrom = createRequire(require('path').resolve(mainScript));
+        undiciModule = tryGetUndici(requireFrom('undici'));
+      }
+    } catch (e) {}
+  }
+
+  if (undiciModule) {
+    proxyAgent = new undiciModule.EnvHttpProxyAgent();
+    undiciModule.setGlobalDispatcher(proxyAgent);
+
+    // Wrap globalThis.fetch to force proxy dispatcher on every call.
+    // This prevents code that overrides the global dispatcher from bypassing the proxy.
+    if (typeof globalThis.fetch === 'function') {
+      var _origFetch = globalThis.fetch;
+      globalThis.fetch = function(input, init) {
+        process.stderr.write('[greywall:node-bootstrap] fetch: ' + (typeof input === 'string' ? input : (input && input.url ? input.url : '?')) + '\n');
+        if (!init) init = {};
+        init.dispatcher = proxyAgent;
+        return _origFetch.call(globalThis, input, init);
+      };
+    }
+
+    // Also wrap undici.fetch and undici.request to catch direct usage
+    if (typeof undiciModule.fetch === 'function') {
+      var _origUndFetch = undiciModule.fetch;
+      undiciModule.fetch = function(input, init) {
+        if (!init) init = {};
+        init.dispatcher = proxyAgent;
+        return _origUndFetch.call(undiciModule, input, init);
+      };
+    }
+    if (typeof undiciModule.request === 'function') {
+      var _origUndRequest = undiciModule.request;
+      undiciModule.request = function(url, opts) {
+        if (!opts) opts = {};
+        opts.dispatcher = proxyAgent;
+        return _origUndRequest.call(undiciModule, url, opts);
+      };
+    }
+  }
+  // --- Shared setup for Parts 2 and 3 ---
+  var url = require('url');
+  var http = require('http');
+  var https = require('https');
+  var tls = require('tls');
+
+  var parsed = new url.URL(proxyUrl);
+  var proxyHost = parsed.hostname;
+  var proxyPort = parseInt(parsed.port, 10);
+
+  var noProxyRaw = process.env.NO_PROXY || process.env.no_proxy || '';
+  var noProxyList = noProxyRaw.split(',').map(function(s) { return s.trim(); }).filter(Boolean);
+
+  function isIPAddress(h) {
+    // IPv4 or IPv6 — skip DNS proxy for raw IPs
+    return /^\d{1,3}(\.\d{1,3}){3}$/.test(h) || h.indexOf(':') !== -1;
+  }
+
+  function shouldProxy(hostname) {
+    if (!hostname || isIPAddress(hostname)) return false;
+    for (var i = 0; i < noProxyList.length; i++) {
+      var p = noProxyList[i];
+      if (p === hostname) return false;
+      if (p.charAt(0) === '.' && hostname.length > p.length &&
+          hostname.indexOf(p, hostname.length - p.length) !== -1) return false;
+      if (p.charAt(0) === '*' && hostname.length >= p.length - 1 &&
+          hostname.indexOf(p.slice(1), hostname.length - p.length + 1) !== -1) return false;
+    }
+    return true;
+  }
+
+  // Save originals before patching
+  var origHttpCreateConnection = http.Agent.prototype.createConnection;
+  var origHttpsCreateConnection = https.Agent.prototype.createConnection;
+
+  // Direct agent for CONNECT requests to the proxy itself (avoids recursion)
+  var directAgent = new http.Agent({ keepAlive: false });
+  directAgent.createConnection = origHttpCreateConnection;
+
+  // --- Part 2: Patch Agent.prototype.createConnection on both http and https ---
+  // This ensures ALL agent instances tunnel through the proxy, not just globalAgent.
+  // Libraries like node-fetch, axios, got create their own agents — patching the
+  // prototype catches them all.
+  try {
+    // Patch https.Agent.prototype — affects ALL https.Agent instances
+    https.Agent.prototype.createConnection = function(options, callback) {
+      var targetHost = options.host || options.hostname;
+      var targetPort = options.port || 443;
+
+      if (!shouldProxy(targetHost)) {
+        return origHttpsCreateConnection.call(this, options, callback);
+      }
+
+      var connectReq = http.request({
+        host: proxyHost,
+        port: proxyPort,
+        method: 'CONNECT',
+        path: targetHost + ':' + targetPort,
+        agent: directAgent,
+      });
+
+      connectReq.on('connect', function(res, socket) {
+        if (res.statusCode === 200) {
+          var tlsSocket = tls.connect({
+            socket: socket,
+            servername: options.servername || targetHost,
+            rejectUnauthorized: options.rejectUnauthorized !== false,
+          });
+          callback(null, tlsSocket);
+        } else {
+          socket.destroy();
+          callback(new Error('Proxy CONNECT failed: ' + res.statusCode));
+        }
+      });
+
+      connectReq.on('error', function(err) { callback(err); });
+      connectReq.end();
+    };
+
+    // Patch http.Agent.prototype — affects ALL http.Agent instances
+    http.Agent.prototype.createConnection = function(options, callback) {
+      var targetHost = options.host || options.hostname;
+      var targetPort = options.port || 80;
+
+      if (!shouldProxy(targetHost)) {
+        return origHttpCreateConnection.call(this, options, callback);
+      }
+
+      var connectReq = http.request({
+        host: proxyHost,
+        port: proxyPort,
+        method: 'CONNECT',
+        path: targetHost + ':' + targetPort,
+        agent: directAgent,
+      });
+
+      connectReq.on('connect', function(res, socket) {
+        if (res.statusCode === 200) {
+          callback(null, socket);
+        } else {
+          socket.destroy();
+          callback(new Error('Proxy CONNECT failed: ' + res.statusCode));
+        }
+      });
+
+      connectReq.on('error', function(err) { callback(err); });
+      connectReq.end();
+    };
+  } catch (e) {}
+
+  // --- Part 3: Patch dns.lookup / dns.promises.lookup to resolve through proxy ---
+  // OpenClaw (and other apps) do DNS resolution before fetch for SSRF protection.
+  // Inside the sandbox, DNS is blocked. Route lookups through the proxy's
+  // /__greywall_dns endpoint which resolves on the host side.
+  try {
+    var dns = require('dns');
+    var dnsPromises = require('dns/promises');
+    var origDnsLookup = dns.lookup;
+    var origDnsPromisesLookup = dnsPromises.lookup;
+
+    function proxyDnsResolve(hostname) {
+      return new Promise(function(resolve, reject) {
+        var req = http.request({
+          host: proxyHost,
+          port: proxyPort,
+          path: '/__greywall_dns?host=' + encodeURIComponent(hostname),
+          method: 'GET',
+          agent: directAgent,
+        }, function(res) {
+          var data = '';
+          res.on('data', function(chunk) { data += chunk; });
+          res.on('end', function() {
+            try {
+              var parsed = JSON.parse(data);
+              if (parsed.error) {
+                var err = new Error(parsed.error);
+                err.code = 'ENOTFOUND';
+                reject(err);
+              } else {
+                resolve(parsed.addresses || []);
+              }
+            } catch(e) {
+              reject(e);
+            }
+          });
+        });
+        req.on('error', reject);
+        req.end();
+      });
+    }
+
+    dnsPromises.lookup = function(hostname, options) {
+      if (!shouldProxy(hostname)) {
+        return origDnsPromisesLookup.call(dnsPromises, hostname, options);
+      }
+
+      return proxyDnsResolve(hostname).then(function(addresses) {
+        if (!addresses || addresses.length === 0) {
+          var err = new Error('getaddrinfo ENOTFOUND ' + hostname);
+          err.code = 'ENOTFOUND';
+          throw err;
+        }
+
+        var opts = (typeof options === 'object' && options !== null) ? options : {};
+        var family = typeof options === 'number' ? options : (opts.family || 0);
+
+        var filtered = addresses;
+        if (family === 4 || family === 6) {
+          filtered = addresses.filter(function(a) { return a.family === family; });
+          if (filtered.length === 0) filtered = addresses;
+        }
+
+        if (opts.all) {
+          return filtered;
+        }
+
+        return filtered[0];
+      });
+    };
+
+    dns.lookup = function(hostname, options, callback) {
+      if (typeof options === 'function') {
+        callback = options;
+        options = {};
+      }
+
+      if (!shouldProxy(hostname)) {
+        return origDnsLookup.call(dns, hostname, options, callback);
+      }
+
+      dnsPromises.lookup(hostname, options).then(function(result) {
+        if (Array.isArray(result)) {
+          callback(null, result);
+        } else {
+          callback(null, result.address, result.family);
+        }
+      }, function(err) {
+        callback(err);
+      });
+    };
+
+  } catch (e) {}
+})();
+`
+
+// nodeProxyBootstrapPath is the path where the bootstrap script is written.
+const nodeProxyBootstrapPath = "/tmp/greywall/node-proxy-bootstrap.js"
+
+// WriteNodeProxyBootstrap writes the Node.js proxy bootstrap script to disk.
+// Returns the path to the script, or an error if it couldn't be written.
+func WriteNodeProxyBootstrap() (string, error) {
+	dir := filepath.Dir(nodeProxyBootstrapPath)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return "", err
+	}
+	if err := os.WriteFile(nodeProxyBootstrapPath, []byte(nodeProxyBootstrapJS), 0o644); err != nil {
+		return "", err
+	}
+	return nodeProxyBootstrapPath, nil
+}
+
 // EncodeSandboxedCommand encodes a command for sandbox monitoring.
 func EncodeSandboxedCommand(command string) string {
 	if len(command) > 100 {
diff --git a/internal/sandbox/utils_test.go b/internal/sandbox/utils_test.go
index a0fbd91..0b8b5c3 100644
--- a/internal/sandbox/utils_test.go
+++ b/internal/sandbox/utils_test.go
@@ -199,6 +199,72 @@ func TestGenerateProxyEnvVars(t *testing.T) {
 	}
 }
 
+func TestGenerateHTTPProxyEnvVars(t *testing.T) {
+	tests := []struct {
+		name         string
+		httpProxyURL string
+		wantEnvs     []string
+		dontWant     []string
+	}{
+		{
+			name:         "no proxy",
+			httpProxyURL: "",
+			wantEnvs: []string{
+				"GREYWALL_SANDBOX=1",
+				"TMPDIR=/tmp/greywall",
+			},
+			dontWant: []string{
+				"HTTP_PROXY=",
+				"HTTPS_PROXY=",
+			},
+		},
+		{
+			name:         "http proxy",
+			httpProxyURL: "http://127.0.0.1:12345",
+			wantEnvs: []string{
+				"GREYWALL_SANDBOX=1",
+				"HTTP_PROXY=http://127.0.0.1:12345",
+				"HTTPS_PROXY=http://127.0.0.1:12345",
+				"http_proxy=http://127.0.0.1:12345",
+				"https_proxy=http://127.0.0.1:12345",
+				"NO_PROXY=",
+				"no_proxy=",
+			},
+			dontWant: []string{
+				"ALL_PROXY=",
+				"all_proxy=",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := GenerateHTTPProxyEnvVars(tt.httpProxyURL)
+
+			for _, want := range tt.wantEnvs {
+				found := false
+				for _, env := range got {
+					if strings.HasPrefix(env, want) || env == want {
+						found = true
+						break
+					}
+				}
+				if !found {
+					t.Errorf("GenerateHTTPProxyEnvVars(%q) missing %q", tt.httpProxyURL, want)
+				}
+			}
+
+			for _, dontWant := range tt.dontWant {
+				for _, env := range got {
+					if strings.HasPrefix(env, dontWant) {
+						t.Errorf("GenerateHTTPProxyEnvVars(%q) should not contain %q, got %q", tt.httpProxyURL, dontWant, env)
+					}
+				}
+			}
+		})
+	}
+}
+
 func TestEncodeSandboxedCommand(t *testing.T) {
 	tests := []struct {
 		name    string