A high-performance virtual Ethernet switch that accepts socket connections from QEMU VMs and provides MAC learning and frame forwarding capabilities with isolated VLANs.

• Isolated VLANs: Each port creates a separate isolated virtual LAN
• MAC Learning: Automatically learns VM MAC addresses from incoming frames
• Efficient Forwarding: Direct unicast forwarding based on learned MAC table
• Broadcast Handling: Intelligent flooding of broadcast frames within each VLAN
• Connection Management: Proper cleanup when VMs disconnect
• Daemon Mode: Can run in background with PID file management
• Concurrent Safe: Thread-safe operations for multiple simultaneous VM connections
• Performance Optimized: Efficient frame processing with minimal overhead

# Start with multiple isolated VLANs (foreground)
./vswitch -ports 9999,9998

# Start as daemon in background
./vswitch -daemon -ports 9999,9998

# Check daemon status
./vswitch -status

# Stop daemon
./vswitch -stop

# Custom configuration
./vswitch -ports 8080,8081 -log-level debug

The virtual switch creates isolated VLANs where:

• Each port represents a separate virtual network segment
• VMs connecting to the same port can communicate with each other
• VMs on different ports are completely isolated
• MAC learning and forwarding occurs independently within each VLAN

As an example, you may have this mapping:

• Port 9999: VLAN 1 (e.g., internal network)
• Port 9998: VLAN 2 (e.g., external network)

Configure QEMU VMs to connect to specific VLANs:

# VM connecting to VLAN 1 (port 9999)
-netdev socket,id=net0,connect=:9999
-device virtio-net-pci,netdev=net0

# VM connecting to VLAN 2 (port 9998)
-netdev socket,id=net0,connect=:9998
-device virtio-net-pci,netdev=net0

The virtual switch supports daemon mode for production deployments:

# Start daemon with custom PID and log files
./vswitch -daemon -pid-file /var/run/vswitch.pid -log-file /var/log/vswitch.log

# Check if daemon is running
./vswitch -status -pid-file /var/run/vswitch.pid

# Stop daemon
./vswitch -stop -pid-file /var/run/vswitch.pid

This virtual switch replaces complex QEMU hubport configurations while providing proper Ethernet switching semantics and better network isolation. Instead of managing multiple hubport configurations, simply:

1. Start the virtual switch with desired ports
2. Configure QEMU VMs to connect to appropriate ports
3. Enjoy automatic MAC learning and proper frame forwarding

# Build the application
make build

# Install to /usr/local/bin
make install

# Clean build artifacts
make clean