Differences between venet and veth

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Revision as of 20:56, 17 June 2008 by Dowdle (talk | contribs) (There were a few typos... and I changed veth to venet with regards to speed and the host node admin config.)
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OpenVZ provides you to use either veth (Virtual eTHernet) or venet (Virtual NETwork) devices (or both) for in-CT networking. Here we describe the differences between those devices.

  • veth allows broadcasts in CT, so you can use even a DHCP server inside a CT, or a samba server with domain broadcasts or other such stuff.
  • veth has some security implications, so is not recommended in untrusted environments like HSP. This is due to broadcasts, traffic sniffing, possible IP collisions etc. i.e. CT's user can actually ruin your ethernet network with such direct access to ethernet layer.
  • With venet device, only OpenVZ host node administrator can assign an IP to a CT. With veth device, network settings can be fully done on CT side by the CT administrator. CT should setup correct gateway, IP/netmask etc. and then a node admin can only choose where your traffic goes.
  • veth devices can be bridged together and/or with other devices. For example, in host system admin can bridge veth from 2 CTs with some VLAN eth0.X. In this case, these 2 CTs will be connected to this VLAN.
  • venet device is a bit faster and more efficient.
  • With veth devices, IPv6 auto generates an address from MAC.

The brief summary:

Differences between veth and venet
Feature veth venet
MAC address Yes No
Broadcasts inside CT Yes No
Traffic sniffing Yes No
Network security Low [1] High
Can be used in bridges Yes No
Performance Fast Fastest
  1. Due to broadcasts, sniffing and possible IP collisions etc.