Linux – How to create a Linux virtual network interface (alias) with a real interface name

linuxnetworking

I want to create a Linux virtual network interface (normally labeled eth0:0) using a real network interface name like eth1.

To put it another way, can I have eth0 and eth1 have different IP addresses but use the same physical network interface?

Is it possible? How?

I have a legacy application which expects two physical network interfaces (eth0 and eth1) which I want to install on a platform which has only one physical network interface.

Best Answer

What you describe are not virtual interfaces, those are just a way (the legacy way, these days you use ip addr from iproute) to assign more than one ip-address to a single interface. Technically, eth0:0 is just eth0.

Related Solutions

Copy Packets from One Interface to Another in Linux

If your kernel is recent enough you could use iptables --tee to forward frames from eth0 to the capture machine.

Debian – How to know what network interface devices the Linux kernel recognises

You can see all networking devices by running:

ifconfig -a

Another trick to debugging the ethernet drivers is to look at dmesg:

dmesg|less

You will see each driver loading and creating ethernet devices.

You mention your ethernet device changing to eth2. Did you copy or move the VM? Typically when you make a copy of a VM it will re-create the MAC address so as to not conflict with the former copy. If this happens udev will assign the "new card" another eth* device and save the previous device for the "missing" card. These rules are stored in:

/etc/udev/rules.d/

Typically in a file called ##-persistant-net.rules. You can safely remove the assignments stored in this file and reboot to have the ethernet devices reassigned.

Best Answer

Related Solutions

Copy Packets from One Interface to Another in Linux

Debian – How to know what network interface devices the Linux kernel recognises

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