<translate><!--T:1-->'''Virtual ethernet Ethernet device''' is an ethernetEthernet-like device which that can be used inside a [[VEcontainer]]. Unlikea [[venet]] network device, a [[veth ]] device has a MAC address. Due to thisTherefore, it can be used in more configurations, when . When veth is bridged to ethX or other device and VE a [[CT0]] network interface (e.g., eth0), the container can act as anindependent host on the network. The container's user fully sets can set up his all of the networking himself, including IPs, gateways , etc.

Virtual ethernet <!--T:2-->A virtual Ethernet device consist consists of two ethernet Ethernet devices - ,one in [[VE0CT0]] (e.g., vethN.0) and another a corresponding one in VECT (e. These devices g., eth0) that are connected to each other, so if . If a packet goes is sent to onedevice it will come out from the other device.

== Virtual ethernet Ethernet device usage ==<!--T:3-->

=== Kernel module ===<!--T:4-->First of all, make sure the The <code>vzethdev</code> module is should be loaded:. You can check it with the following commands.

You might want to add the module to === MAC addresses === <code>/etc/init.d/vz script</code!--T:6-->The following steps to generate a MAC address are not necessary, so it since newer versionsof vzctl will be loaded during startupautomatically generate a MAC address for you. These steps are providedin case you want to set a MAC address manually.

{{Note|since vzctl version 3<!--T:7-->You should use a random MAC address when adding a network interface to a container.0.11Do not use MAC addresses of real eth devices, vzethdev is loaded by /etc/initbecause this can lead to collisions.d/vz}}

=== Adding veth to <!--T:9-->There is a VE ===utility script available for generating MAC addresses: https://github.com/moutai/eucalyptus-utils/blob/master/easymac.sh. It is used like this:

{{Note|Use random MAC addresses <!--T:10-->chmod +x easymac.sh . Do not use MAC addresses of real eth devices, because this can lead to collisions and MAC addresses must be entered in XX:XX:XX:XX:XX:XX format/easymac.}}sh -R

==== syntax vzctl version < 3.0.14 =Adding veth to a CT ===<!--T:11-->

<pre!--T:12-->vzctl set <VEIDCTID> --veth_add netif_add <dev_nameifname>[,<dev_addrmac>,<ve_dev_namehost_ifname>,<ve_dev_addrhost_mac>,</prebridge>]

<!--T:13-->Here * <tt>dev_nameifname</tt> is the ethernet Ethernet device name that you are creating on in the [[VE0|host system]]CT* <tt>dev_addrmac</tt> is its MAC addressin the CT* <tt>ve_dev_namehost_ifname</tt> is the corresponding ethernet Ethernet device name you are creating on the VEhost ([[CT0]])* <tt>ve_dev_addrhost_mac</tt> is its MAC addresson the host ([[CT0]]), if you want independent communication with the Container through the bridge, you should explicitly specify multicast MAC address here (FE:FF:FF:FF:FF:FF). {{Note| that this option * <tt>bridge</tt> is incremental, so devices are added an optional parameter which can be used in custom network start scripts to automatically add the interface to a bridge. (See the reference to already existing onesthe vznetaddbr script below and persistent bridge configurations.}})

NB there <!--T:14-->{{Note|All parameters except <code>ifname</code> are no spaces after the commasoptional. Missing parameters, except for bridge, are automatically generated, if not specified.}}

<pre>vzctl set 101 !--veth_add veth101.0,00:12:34:56:78:9A,eth0,00:12:34:56:78T:9B 16--save</pre>After executing this command <tt>veth</tt> device will be created for VE vzctl set 101 and veth configuration will be saved to a VE configuration file.Host-side ethernet device will have <tt>veth101.0</tt> name and <tt>00:12:34:56:78:9A</tt> MAC address.VE-side ethernet device will have <tt>netif_add eth0</tt> name and <tt>00:12:34:56:78:9B</tt> MAC address.  ==== syntax vzctl version >= 3.0.14 ==== Read Update infos about [http://openvz.org/news/updates/vzctl-3.0.14-1 vzctl 3.0.14] <pre>vzctl set <VEID> --netif_add <ifname>[,<mac>,<host_ifname>,<host_mac]</pre> Here* <tt>ifname</tt> is the ethernet device name in the VE* <tt>mac</tt> is its MAC address in the VE* <tt>host_ifname</tt> is the ethernet device name on the host ([[VE0]])* <tt>host_mac</tt> is its MAC address on the host ([[VE0]]) {{Note|All parameters except ifname are optional and are automatically generated if not specified.}}save

Example<!--T:17-->If you want to specify everything:

<pre!--T:18-->

==== syntax <!--T:20-->vzctl version < 3set 101 --netif_add eth0,00:12:34:56:78:9A,veth101.0.14 ====,FE:FF:FF:FF:FF:FF,vzbr0 --save

<pre>vzctl set <VEID> !--T:21--veth_del <dev_name></pre>Here <tt>dev_name</tt> is If you want to specify the ethernet device name in bridge and autogenerate the [[VE0|host system]].other values:

Example <!--T:<pre22-->vzctl set 101 --veth_del veth101.0 netif_add eth0,,,,vzbr0 --save</pre>After executing this command veth device with host-side ethernet name veth101.0 will be removed from VE 101 and veth configuration will be updated in VE config file.

==== syntax vzctl version >= 3.0.14 ==== <pre!--T:24-->vzctl set <VEIDCTID> --netif_del <dev_name>|all</pre>

* <code>dev_name</code> is the ethernet Ethernet device name in the [[VECT]].

<!--T:26-->{{Note|If you want to remove all ethernet Ethernet devices in VECT, use <code>all</code>.}}

<pre!--T:28-->

== Common configurations with virtual ethernet Ethernet devices ==<!--T:29-->

=== Simple configuration with virtual ethernet Ethernet device ===<!--T:30--> <!--T:31-->Assuming that 192.168.0.0/24 is being used on your LAN, the following sections show how to configure a container for the LAN using veth. ==== Start a CT ==== <!--T:32-->

==== Start a VE ==== <pre!--T:33-->

==== Add veth device to VE CT ====<!--T:34-->  <pre!--T:35-->[host-node]# vzctl set 101 --veth_add veth101.0,00:12:34:56:78:9A,netif_add eth0,00:12:34:56:78:9B --save </pre!--T:36-->This allocates a MAC address and associates it with the host eth0 port.

==== Configure devices in VE0 CT0 ====<!--T:37-->The following steps are needed when the [[CT]] is '''not''' bridged to a [[CT0]] network interface. That is because the [[CT]] is connected to a virtual network that is "behind" [[CT0]]. [[CT0]] must forward packets between its physical network interface and the virtual network interface where [[CT]] is located. The first step below to configure the interface is not necessary if the container has been started, since the device will have been initialized.

==== Configure device in VE CT ====<!--T:38-->The following steps show an example of a quick manual configuration of the [[CT]] network interface. Typically, you would configure the network settings in /etc/network/interfaces (Debian, see below) or however it is normally configured on your distribution. You can also comment or remove the configuration for venet0, if it exists, because that device will not be used.

<!--T:39-->Notes:* Until you ifconfig eth0 it won't appear. When you do it will use the mac address netif_add added earlier* 192.168.0.101 is chosen to be an [[unrouteable private ip address]]. Where 101 reminds you that it is node 101.* The "ip route" tells all traffic to head to "device eth0"* In theory you could [[use dhcpd with OpenVZ]] and dhclient to pick up an DHCP address from your router instead of hardwiring it** http://openvz.org/pipermail/users/2005-November/000020.html ==== Add route in [[VE0CT0]] ====<pre!--T:40-->Since [[CT0]] is acting as a router between its physical network interface and the virtual network interface of the [[CT]], we need to add a route to the [[CT]] to direct traffic to the right destination. [host-node]# ip route add 192.168.0.101 dev veth101.0 === Using a directly routed IPv4 with virtual Ethernet device === <!--T:41--> ==== Situation ==== <!--T:42-->Hardware Node (HN/CT0) has 192.168.0.1/pre24 with router 192.168.0.254. <!--T:43-->We also know that IPv4 10.0.0.1/32 is directly routed to 192.168.0.1 (this is called a ''fail-over IP''). <!--T:44-->We want to give this directly routed IPv4 address to a container (CT).

=== Virtual ethernet device with IPv6 =Start container ==== <!--T:45-->

==== Start [[VE]] ==== <pre!--T:46-->

==== Add veth device to CT ==== <!--T:47-->  <!--T:48-->[[VE]host-node] # vzctl set 101 --netif_add eth0 --save <!--T:49-->This allocates a MAC address and associates it with the host eth0 port. ==== Configure device and add route in CT0 ====<!--T:50--> <!--T:51-->

[host-node]# vzctl set 101 ifconfig veth101.0 0[host--veth_add node]# ip route add 10.0.0.1 dev veth101.0,00:12:34:56:78:9A,eth0,00:12:34:56:78:9B --save

==== Configure devices <!--T:52-->You can automatize this at VPS creation by using a mount script <tt>$VEID.mount</tt>. <!--T:53-->The problem here is that the ''veth'' interface appears in [[VE0]] ====CT0 '''after''' VPS has started, therefore we cannot directly use the commands in the mount script. We launch a shell script (enclosed by { }) in background (operator '''&''') that waits for the interface to be ready and then adds the IP route. <!--T:54-->Contents of the mount script <tt>/etc/vz/conf/101.mount</tt>:

[host#!/bin/bash# This script source VPS configuration files in the same order as vzctl does <!--T:55--node]># ifconfig veth101.0 0if one of these files does not exist then something is really broken[host-node]# echo 1 > f /procetc/sys/net/ipv6vz/vz.conf/veth101.0/forwarding] || exit 1[host-nodef $VE_CONFFILE ]# echo || exit 1  <!--T:56--> # source both files. Note the order, it is important. /procetc/sys/net/ipv6vz/vz.conf/eth0/forwarding[host. $VE_CONFFILE <!--T:57--node]># echo Configure veth with IP after VPS has started{ IP=X.Y.Z.T DEV=veth101.0 while sleep 1 > ; do /procsbin/sysifconfig $DEV 0 >/netdev/ipv6null 2>&1 if [ $? -eq 0 ]; then /confsbin/all/forwardingip route add $IP dev $DEV break fi done} &

==== Configure device Make sure IPv4 forwarding is enabled in [[VE]] CT0 ====<!--T:58--> <!--T:59-->

[host-node]# vzctl enter 101echo 1 > /proc/sys/net/ipv4/ip_forward[vehost-101node]# echo 1 > /sbinproc/sys/net/ipv4/conf/ifconfig eth0 /forwarding[host-node]# echo 1 > /proc/sys/net/ipv4/conf/veth101.0/forwarding

==== Start router advertisement daemon (radvd) for IPv6 Configure device in VE0 CT ====First you need to edit radvd configuration file. Here is a simple example of <tt>/etc/radv.conf</tt>!--T:<pre60-->interface veth101.0{ AdvSendAdvert on; MinRtrAdvInterval 3; MaxRtrAdvInterval 10; AdvHomeAgentFlag off;

prefix 3ffe<!--T:2400:0:0::/64 { AdvOnLink on; AdvAutonomous on; AdvRouterAddr off; };61-->};1. Configure IP address

prefix 3ffe<!--T:0302:0011:0002::/64 { AdvOnLink on; AdvAutonomous on; AdvRouterAddr off;63--> };};</pre>3. Add default route

Then, start radvd<!--T:64-->

[hostve-node101]# /etcsbin/initifconfig eth0 10.d0.0.1 netmask 255.255.255.255[ve-101]# /sbin/ip route add 192.168.0.1 dev eth0[ve-101]# /radvd startsbin/ip route add default via 192.168.0.1

[host-node]# ip addr add dev veth101auto eth0iface eth0 inet static address 10.0.0 3ffe:2400::212:34ff:fe56:789a.1 netmask 255.255.255.255 up /sbin/64[host-node]# ip addr route add 192.168.0.1 dev eth0 3ffe:0302:0011:0002:211:22ff:fe33:4455 up /sbin/64ip route add default via 192.168.0.1

=== Virtual ethernet devices can be joined in one bridge Ethernet device with IPv6 ===Perform steps 1 <!- 4 from Simple configuration chapter for several VEs and/or veth devices-T:66-->

<!--T:67-->See the [[VEs and HNs in same subnets]] article. === Independent Virtual Ethernet communication through the bridge === <!--T:68-->Bridging a [[CT]] interface to a [[CT0]] interface is the magic that allows the [[CT]] to be an independent host on the network with its own IP address, gateway, etc. [[CT0]] does not need any configuration for forwarding packets to the [[CT]] or performing proxy arp for the [[CT]] or event the routing. <!--T:69-->To manually configure a bridge and add devices to it, perform steps 1 - 4 from Simple configuration chapter for several containers and/or veth devices using FE:FF:FF:FF:FF:FF as a [[CT0]] veth side MAC address and then follow these steps. ==== Create bridge device ====<!--T:70-->

==== Add veth devices to bridge ====<!--T:71-->

==== Configure bridge device ====<!--T:72-->

===Automating the bridge = Add routes == <!--T:73-->The most convenient method is to automatically create the bridge at boot as a network interface, add the physical interface from [[CT0]] and then add the interface from each [[CT]] as it starts. All devices are connected to a virtual switch, and containers directly access the network just as any other host without additional configuration on [[CT0]]. <!--T:74-->In Debian, configure the network interface on [[CT0]] to plug into a bridge in /etc/network/interfaces. The [[VE0CT0]] ====physical device is added to the bridge as the "uplink" port to the physical network. You need to have bridge-utils installed for this to work. <!--T:75-->The bridge forwarding delay is set to 0 seconds so that forwarding begins immediately when a new interface is added to a bridge. The default delay is 30 seconds, during which the bridge pauses all traffic to listen and figure out where devices are. This can interrupt services when a container is added to the bridge. If you aren't running the spanning tree protocol (off by default) and the bridge does not create a loop in your network, then there is no need for a forwarding delay.

[hostiface eth0 inet manual <!-node]# ip route add 192.168.101.1 dev -T:76-->auto vzbr0iface vzbr0inet static... bridge_ports eth0[host-node]# ip route add 192.168.101.n dev vzbr0 bridge_fd 0[host-node]# ip route add address 192.168.102.1 dev vzbr0...100 netmask 255.255.255.0[host-node]# ip route add gateway 192.168.XXX1.N dev vzbr0254

Thus you'll have more convinient configuration=== Making a veth-device persistent === <!--T:77-->These steps are no longer necessary, ias the veth device is automatically created when the container is started.e. all routes to VEs will be through this bridge and VEs can communicate with each other even without these routesThey remain here as a reference.

=== Making a bridged veth-device persistent ===<!--T:81-->

At <!--T:82-->Like the momentabove example, here it is not possible how to have add the commands needed for veth device to a bridge in a persistent veth being made automatically be vzctl. A bugreport ( http://bugzilla.openvz.org/show_bug.cgi?id=301 ) has already been made. Until then, here's a way to make the above steps persistent.

1. First<!--T:83-->vzctl includes a 'vznetaddbr' script, edit which makes use of the VE's configuration to specify what 'bridge'' parameter of the veth's IP address(es) should be, and to indicate that a custom script should be run when starting up a VE--netif_add switch. * Open up /etc/vz/conf/VEID.conf * Comment out any IP_ADDRESS entries to prevent a VENET-device from being created in the VE * Add or change the entry CONFIG_CUSTOMIZED="yes" * Add an entry VETH_IP_ADDRESS="<VE IP>" The VE IP can have multiple IPs, separated by spaces

2. Now to <!--T:84-->Just create that "custom script". The following helper script will check the configuration file for IP addresses and for the veth interface, and configure the IP routing accordingly. Create the script /usretc/sbinvz/vznetaddroute to have vznet.conf containing the following, and then <code>chmod 0500 /usr/sbin/vznetaddroute</code> to make it executable.

#!/bin/bash# EXTERNAL_SCRIPT="/usr/sbin/vznetaddroute# a script to bring up bridged network interfaces (veth's) in a VE CONFIGFILE=/etc/vz/conf/$VEID.conf. $CONFIGFILEVZHOSTIF=`echo $NETIF |sed 's/^.*host_ifname=\(.*\),.*$/\1/g'` if [ ! -n "$VETH_IP_ADDRESSvznetaddbr" ]; then echo "According to $CONFIGFILE VE$VEIDI has no veth IPs configured." exit 1fi if [ ! -n "$VZHOSTIF" ]; then echo "According to $CONFIGFILE VE$VEIDI has no veth interface configured." exit 1fi for IP in $VETH_IP_ADDRESS; do echo "Adding interface $VZHOSTIF and route $IP for VE$VEID to VE0" /sbin/ifconfig $VZHOSTIF 0 echo 1 > /proc/sys/net/ipv4/conf/$VZHOSTIF/proxy_arp echo 1 > /proc/sys/net/ipv4/conf/$VZHOSTIF/forwarding /sbin/ip route add $IP dev $VZHOSTIFdone exit 0

3. Now create /etc/vz/vznet.conf containing the following. This is what defines the "custom script" as being the vznetaddroute which you <!--T:86-->Or just created.run command

#!/bin/bashecho 'EXTERNAL_SCRIPT="/usr/sbin/vznetaddroutevznetaddbr"' > /etc/vz/vznet.conf

4. Of course, the VE<!--T:87-->The script uses 'vmbr0's operating system will need to be configured with those IP address(es) as well. Consult the manual for your VE's OS for details. That's it! At this point, default bridge name when you restart the VE you should see a new line in the output, indicating that the interface no bridge is being configured and a new route being added. And you should be able to ping the host, and to enter the VE and use the networkspecified.

=== Virtual ethernet Ethernet devices + VLAN ===<!--T:88-->

== See also ==<!--T:89-->

== External links ==<!--T:90-->