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I have a qemu debian guest that is being launched with the following command.

qemu-system-x86_64 -boot order=c -drive file=image.img,if=virtio -enable-kvm -netdev type=user,id=net0,hostfwd=tcp: -device virtio-net,netdev=net0 -vga std

However within the guest there are two visible network interfaces.

Output from lshw

         description: Ethernet interface  
         product: 82540EM Gigabit Ethernet Controller  
         vendor: Intel Corporation  
         physical id: 3  
         bus info: pci@0000:00:03.0  
         logical name: eth0  
         version: 03  
         serial: 52:54:00:12:34:56  
         size: 1Gbit/s  
         capacity: 1Gbit/s  
         width: 32 bits  
         clock: 33MHz  
         capabilities: bus_master rom ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd   1000bt-fd autonegotiation  
         configuration: autonegotiation=on broadcast=yes driver=e1000   driverversion=7.3.21-k8-NAPI duplex=full firmware=N/A latency=0 link=yes multicast=yes   port=twisted pair speed=1Gbit/s  
         resources: irq:11 memory:febc0000-febdffff ioport:c000(size=64)   memory:feb40000-feb7ffff` 

         description: Ethernet controller  
         product: Virtio network device  
         vendor: Red Hat, Inc  
         physical id: 4  
         bus info: pci@0000:00:04.0  
         version: 00  
         width: 32 bits  
         clock: 33MHz  
         capabilities: msix bus_master cap_list rom  
         configuration: driver=virtio-pci latency=0  
         resources: irq:10 ioport:c080(size=32) memory:febf0000-febf0fff   memory:feb80000-febbffff

To my understanding, I only specified a single interface when launching the guest, so why are there two? network:1 makes sense, that is the Virtio interface, but why is network:0 there?


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