Add support for local outbound connections in sandbox configuration

README.md

@@ -71,6 +71,7 @@ Create `~/.fence.json` to configure allowed domains and filesystem access:
 | `allowUnixSockets` | List of allowed Unix socket paths (macOS) |
 | `allowAllUnixSockets` | Allow all Unix sockets |
 | `allowLocalBinding` | Allow binding to local ports |
+| `allowLocalOutbound` | Allow outbound connections to localhost, e.g., local DBs (defaults to `allowLocalBinding` if not set) |
 | `httpProxyPort` | Fixed port for HTTP proxy (default: random available port) |
 | `socksProxyPort` | Fixed port for SOCKS5 proxy (default: random available port) |
 
@@ -138,6 +139,12 @@ import (
 )
 
 func main() {
+    // Check if platform supports sandboxing (macOS/Linux)
+    if !fence.IsSupported() {
+        fmt.Println("Sandboxing not supported on this platform")
+        return
+    }
+
     // Create config
     cfg := &fence.Config{
         Network: fence.NetworkConfig{

internal/config/config.go

@@ -25,6 +25,7 @@ type NetworkConfig struct {
 	AllowUnixSockets    []string `json:"allowUnixSockets,omitempty"`
 	AllowAllUnixSockets bool     `json:"allowAllUnixSockets,omitempty"`
 	AllowLocalBinding   bool     `json:"allowLocalBinding,omitempty"`
+	AllowLocalOutbound  *bool    `json:"allowLocalOutbound,omitempty"` // If nil, defaults to AllowLocalBinding value
 	HTTPProxyPort       int      `json:"httpProxyPort,omitempty"`
 	SOCKSProxyPort      int      `json:"socksProxyPort,omitempty"`
 }

internal/sandbox/macos.go

@@ -33,6 +33,7 @@ type MacOSSandboxParams struct {
 	AllowUnixSockets        []string
 	AllowAllUnixSockets     bool
 	AllowLocalBinding       bool
+	AllowLocalOutbound      bool
 	ReadDenyPaths           []string
 	WriteAllowPaths         []string
 	WriteDenyPaths          []string
@@ -419,10 +420,15 @@ func GenerateSandboxProfile(params MacOSSandboxParams) string {
 		profile.WriteString("(allow network*)\n")
 	} else {
 		if params.AllowLocalBinding {
+			// Allow binding and inbound connections on localhost (for servers)
 			profile.WriteString(`(allow network-bind (local ip "localhost:*"))
 (allow network-inbound (local ip "localhost:*"))
-(allow network-outbound (local ip "localhost:*"))
 `)
+			// Process can make outbound connections to localhost
+			if params.AllowLocalOutbound {
+				profile.WriteString(`(allow network-outbound (local ip "localhost:*"))
+`)
+			}
 		}
 
 		if params.AllowAllUnixSockets {
@@ -492,6 +498,11 @@ func WrapCommandMacOS(cfg *config.Config, command string, httpPort, socksPort in
 	// Enable local binding if ports are exposed or if explicitly configured
 	allowLocalBinding := cfg.Network.AllowLocalBinding || len(exposedPorts) > 0
 
+	allowLocalOutbound := allowLocalBinding
+	if cfg.Network.AllowLocalOutbound != nil {
+		allowLocalOutbound = *cfg.Network.AllowLocalOutbound
+	}
+
 	params := MacOSSandboxParams{
 		Command:                 command,
 		NeedsNetworkRestriction: needsNetwork || len(cfg.Network.AllowedDomains) == 0, // Block if no domains allowed
@@ -500,6 +511,7 @@ func WrapCommandMacOS(cfg *config.Config, command string, httpPort, socksPort in
 		AllowUnixSockets:        cfg.Network.AllowUnixSockets,
 		AllowAllUnixSockets:     cfg.Network.AllowAllUnixSockets,
 		AllowLocalBinding:       allowLocalBinding,
+		AllowLocalOutbound:      allowLocalOutbound,
 		ReadDenyPaths:           cfg.Filesystem.DenyRead,
 		WriteAllowPaths:         allowPaths,
 		WriteDenyPaths:          cfg.Filesystem.DenyWrite,
@@ -510,6 +522,9 @@ func WrapCommandMacOS(cfg *config.Config, command string, httpPort, socksPort in
 	if debug && len(exposedPorts) > 0 {
 		fmt.Fprintf(os.Stderr, "[fence:macos] Enabling local binding for exposed ports: %v\n", exposedPorts)
 	}
+	if debug && allowLocalBinding && !allowLocalOutbound {
+		fmt.Fprintf(os.Stderr, "[fence:macos] Blocking localhost outbound (AllowLocalOutbound=false)\n")
+	}
 
 	profile := GenerateSandboxProfile(params)
 

pkg/fence/fence.go

@@ -3,9 +3,15 @@ package fence
 
 import (
 	"github.com/Use-Tusk/fence/internal/config"
+	"github.com/Use-Tusk/fence/internal/platform"
 	"github.com/Use-Tusk/fence/internal/sandbox"
 )
 
+// IsSupported returns true if the current platform supports sandboxing (macOS/Linux).
+func IsSupported() bool {
+	return platform.IsSupported()
+}
+
 // Config is the configuration for fence.
 type Config = config.Config