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Promiscuous Mode and interfaces

posted Sep 6, 2011, 12:58 PM by Andre Rossouw
Promiscuous mode is required for correct operation of bridging - especially with OpenVPN in bridge mode as a guest. Example interfaces file:

# The loopback network interface auto lo iface lo inet loopback # Create our bridge interface using a static IP address on the network auto br0 iface br0 inet static address netmask network broadcast gateway pre-up ifconfig eth0 down pre-up ifconfig eth0 promisc up pre-up brctl addbr br0 pre-up brctl addif br0 eth0 bridge_fd 9 bridge_hello 2 bridge_maxage 12 bridge_stp off # Configure the actual Ethernet device in promiscuous mode and # add it to the bridge iface eth0 inet manual pre-up ifconfig eth0 promisc up pre-up brctl addif br0 eth0 pre-down brctl delif br0 eth0 pre-down ifconfig eth0 down

As a side note - Microsoft Hyper-V does not support promiscuous mode. This equals a fail for any services that need this, typically security, vpn and packet inspection appliances.
Hyper-V has only wasted 2 days of my life... :|