Using 2 nics not working

examples/netstack-proxying/main.go

@@ -0,0 +1,181 @@
+// Example of using netstack2 TCP/UDP proxying with WireGuard
+//
+// This example shows how to enable transparent TCP/UDP proxying
+// through a WireGuard tunnel using netstack.
+//
+// Build: go build -o example examples/proxying/main.go
+// Run: ./example
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/netip"
+
+	"github.com/fosrl/newt/netstack2"
+)
+
+func main() {
+	fmt.Println("Netstack2 TCP/UDP Proxying Examples")
+	fmt.Println("====================================\n")
+
+	// Example 1: Recommended - Subnet-based proxying (dual-interface)
+	example1()
+
+	// Example 2: Single interface with proxying (may conflict with WireGuard)
+	example2()
+
+	// Example 3: Enable proxying after creation (single interface)
+	example3()
+
+	// Example 4: Standard netstack without proxying (backward compatible)
+	example4()
+}
+
+func example1() {
+	fmt.Println("=== Example 1: Subnet-Based Proxying (Recommended) ===")
+	fmt.Println("This approach avoids conflicts with WireGuard by using a secondary NIC")
+
+	localAddresses := []netip.Addr{
+		netip.MustParseAddr("10.0.0.2"),
+	}
+	dnsServers := []netip.Addr{
+		netip.MustParseAddr("1.1.1.1"),
+	}
+	mtu := 1420
+
+	// Create netstack normally (no proxying on main interface)
+	tun, tnet, err := netstack2.CreateNetTUN(localAddresses, dnsServers, mtu)
+	if err != nil {
+		log.Fatalf("Failed to create netstack: %v", err)
+	}
+	defer tun.Close()
+
+	fmt.Println("✓ Netstack created (WireGuard uses NIC 1)")
+
+	// Define subnets that should be proxied
+	proxySubnets := []netip.Prefix{
+		netip.MustParsePrefix("192.168.1.0/24"), // Internal services
+		netip.MustParsePrefix("10.20.0.0/16"),   // Application subnet
+	}
+
+	// Enable proxying on a secondary NIC for these subnets
+	err = tnet.EnableProxyOnSubnet(proxySubnets, true, true)
+	if err != nil {
+		log.Fatalf("Failed to enable proxy on subnet: %v", err)
+	}
+
+	fmt.Println("✓ TCP/UDP proxying enabled on NIC 2 for:")
+	for _, subnet := range proxySubnets {
+		fmt.Printf("  - %s\n", subnet)
+	}
+	fmt.Println("✓ Routing table updated to direct subnet traffic to proxy NIC")
+	fmt.Println("  → WireGuard on NIC 1: handles encryption/decryption")
+	fmt.Println("  → Proxy on NIC 2: handles TCP/UDP termination for specified subnets")
+
+	fmt.Println()
+}
+
+func example2() {
+	fmt.Println("=== Example 2: Single Interface with Proxying (Not Recommended) ===")
+	fmt.Println("⚠️  May conflict with WireGuard packet handling!")
+
+	localAddresses := []netip.Addr{
+		netip.MustParseAddr("10.0.0.2"),
+	}
+	dnsServers := []netip.Addr{
+		netip.MustParseAddr("1.1.1.1"),
+	}
+	mtu := 1420
+
+	// Create netstack with both TCP and UDP proxying enabled
+	tun, tnet, err := netstack2.CreateNetTUNWithOptions(
+		localAddresses,
+		dnsServers,
+		mtu,
+		netstack2.NetTunOptions{
+			EnableTCPProxy: true,
+			EnableUDPProxy: true,
+		},
+	)
+	if err != nil {
+		log.Fatalf("Failed to create netstack: %v", err)
+	}
+	defer tun.Close()
+
+	fmt.Println("✓ Netstack created with TCP and UDP proxying enabled")
+	fmt.Println("  → Any TCP/UDP traffic through the tunnel will be proxied to actual targets")
+
+	// Now any TCP or UDP connection made through the tunnel will be
+	// automatically terminated in netstack and proxied to the target
+
+	_ = tnet
+	fmt.Println()
+}
+
+func example2() {
+	fmt.Println("=== Example 2: Enable proxying after creation ===")
+
+	localAddresses := []netip.Addr{
+		netip.MustParseAddr("10.0.0.3"),
+	}
+	dnsServers := []netip.Addr{
+		netip.MustParseAddr("1.1.1.1"),
+	}
+	mtu := 1420
+
+	// Create standard netstack first
+	tun, tnet, err := netstack2.CreateNetTUN(localAddresses, dnsServers, mtu)
+	if err != nil {
+		log.Fatalf("Failed to create netstack: %v", err)
+	}
+	defer tun.Close()
+
+	fmt.Println("✓ Netstack created")
+
+	// Enable TCP proxying
+	if err := tnet.EnableTCPProxy(); err != nil {
+		log.Fatalf("Failed to enable TCP proxy: %v", err)
+	}
+	fmt.Println("✓ TCP proxying enabled")
+
+	// Enable UDP proxying
+	if err := tnet.EnableUDPProxy(); err != nil {
+		log.Fatalf("Failed to enable UDP proxy: %v", err)
+	}
+	fmt.Println("✓ UDP proxying enabled")
+
+	// Calling EnableTCPProxy again is safe (no-op)
+	if err := tnet.EnableTCPProxy(); err != nil {
+		log.Fatalf("Failed to re-enable TCP proxy: %v", err)
+	}
+	fmt.Println("✓ Re-enabling TCP proxying is safe (no-op)")
+
+	fmt.Println()
+}
+
+func example3() {
+	fmt.Println("=== Example 3: Standard netstack (no proxying) ===")
+
+	localAddresses := []netip.Addr{
+		netip.MustParseAddr("10.0.0.4"),
+	}
+	dnsServers := []netip.Addr{
+		netip.MustParseAddr("1.1.1.1"),
+	}
+	mtu := 1420
+
+	// Use standard CreateNetTUN - backward compatible
+	tun, tnet, err := netstack2.CreateNetTUN(localAddresses, dnsServers, mtu)
+	if err != nil {
+		log.Fatalf("Failed to create netstack: %v", err)
+	}
+	defer tun.Close()
+
+	fmt.Println("✓ Standard netstack created (no proxying)")
+	fmt.Println("  → Use tnet.DialTCP(), tnet.DialUDP() for manual connections")
+
+	_ = tnet
+	fmt.Println()
+}