Virtual Ethernet
The veth devices are virtual Ethernet devices. They can act as tunnels between network namespaces to create a bridge to a physical network device in another namespace or VRF, but can also be used as standalone network devices.
Note
veth interfaces need to be created in pairs - it’s called the peer name
Configuration
Common interface configuration
Configure interface <interface> with one or more interface addresses.
address can be specified multiple times as IPv4 and/or IPv6 address, e.g. 192.0.2.1/24 and/or 2001:db8::1/64
dhcp interface address is received by DHCP from a DHCP server on this segment.
dhcpv6 interface address is received by DHCPv6 from a DHCPv6 server on this segment.
Note
When using DHCP to retrieve IPv4 address and if local customizations are needed, they should be possible using the enter and exit hooks provided. The hook dirs are:
/config/scripts/dhcp-client/pre-hooks.d//config/scripts/dhcp-client/post-hooks.d/
Example:
set interfaces virtual-ethernet veth0 address 192.0.2.1/24
set interfaces virtual-ethernet veth0 address 2001:db8::1/64
set interfaces virtual-ethernet veth0 address dhcp
set interfaces virtual-ethernet veth0 address dhcpv6
Set a human readable, descriptive alias for this connection. Alias is used by
e.g. the show interfaces command or SNMP based monitoring tools.
Example:
set interfaces virtual-ethernet veth0 description 'This is an awesome interface running on VyOS'
VLAN
Regular VLANs (802.1q)
IEEE 802.1q, often referred to as Dot1q, is the networking standard that supports virtual LANs (VLANs) on an IEEE 802.3 Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the accompanying procedures to be used by bridges and switches in handling such frames. The standard also contains provisions for a quality-of-service prioritization scheme commonly known as IEEE 802.1p and defines the Generic Attribute Registration Protocol.
Portions of the network which are VLAN-aware (i.e., IEEE 802.1q conformant) can include VLAN tags. When a frame enters the VLAN-aware portion of the network, a tag is added to represent the VLAN membership. Each frame must be distinguishable as being within exactly one VLAN. A frame in the VLAN-aware portion of the network that does not contain a VLAN tag is assumed to be flowing on the native VLAN.
The standard was developed by IEEE 802.1, a working group of the IEEE 802 standards committee, and continues to be actively revised. One of the notable revisions is 802.1Q-2014 which incorporated IEEE 802.1aq (Shortest Path Bridging) and much of the IEEE 802.1d standard.
802.1q VLAN interfaces are represented as virtual sub-interfaces in VyOS. The
term used for this is vif.
Create a new VLAN interface on interface <interface> using the VLAN number provided via <vlan-id>.
You can create multiple VLAN interfaces on a physical interface. The VLAN ID range is from 0 to 4094.
Note
Only 802.1Q-tagged packets are accepted on Ethernet vifs.
Configure interface <interface> with one or more interface addresses.
address can be specified multiple times as IPv4 and/or IPv6 address, e.g. 192.0.2.1/24 and/or 2001:db8::1/64
dhcp interface address is received by DHCP from a DHCP server on this segment.
dhcpv6 interface address is received by DHCPv6 from a DHCPv6 server on this segment.
Note
When using DHCP to retrieve IPv4 address and if local customizations are needed, they should be possible using the enter and exit hooks provided. The hook dirs are:
/config/scripts/dhcp-client/pre-hooks.d//config/scripts/dhcp-client/post-hooks.d/
Example:
set interfaces virtual-ethernet veth0 vif 10 address 192.0.2.1/24
set interfaces virtual-ethernet veth0 vif 10 address 2001:db8::1/64
set interfaces virtual-ethernet veth0 vif 10 address dhcp
set interfaces virtual-ethernet veth0 vif 10 address dhcpv6
Set a human readable, descriptive alias for this connection. Alias is used by
e.g. the show interfaces command or SNMP based monitoring tools.
Example:
set interfaces virtual-ethernet veth0 vif 10 description 'This is an awesome interface running on VyOS'
Disable given <interface>. It will be placed in administratively down
(A/D) state.
Example:
set interfaces virtual-ethernet veth0 vif 10 disable
Use this command to direct an interface to not detect any physical state changes on a link, for example, when the cable is unplugged.
Default is to detects physical link state changes.
Example:
set interfaces virtual-ethernet veth0 vif 10 disable-link-detect
Configure user defined MAC address on given <interface>.
Example:
set interfaces virtual-ethernet veth0 vif 10 mac '00:01:02:03:04:05'
Configure MTU on given <interface>. It is the size (in bytes) of the largest ethernet frame sent on this link.
Example:
set interfaces virtual-ethernet veth0 vif 10 mtu 1600
As Internet wide PMTU discovery rarely works, we sometimes need to clamp our TCP MSS value to a specific value. This is a field in the TCP options part of a SYN packet. By setting the MSS value, you are telling the remote side unequivocally ‘do not try to send me packets bigger than this value’.
Note
This command was introduced in VyOS 1.4 - it was previously called:
set firewall options interface <name> adjust-mss <value>
Hint
MSS value = MTU - 20 (IP header) - 20 (TCP header), resulting in 1452 bytes on a 1492 byte MTU.
Instead of a numerical MSS value clamp-mss-to-pmtu can be used to automatically set the proper value.
Once a neighbor has been found, the entry is considered to be valid for at least for this specific time. An entry’s validity will be extended if it receives positive feedback from higher level protocols.
This defaults to 30 seconds.
Example:
set interfaces virtual-ethernet veth0 vif 10 ip arp-cache-timeout 180
If set the kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load-balancing, does this behaviour cause problems.
If not set (default) allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP’d IP out that interface (therefore you must use source based routing for this to work).
In other words it allows control of which cards (usually 1) will respond to an arp request.
Example:
set interfaces virtual-ethernet veth0 vif 10 ip disable-arp-filter
Configure interface-specific Host/Router behaviour. If set, the interface will switch to host mode and IPv6 forwarding will be disabled on this interface.
set interfaces virtual-ethernet veth0 vif 10 ip disable-forwarding
Define different modes for IP directed broadcast forwarding as described in RFC 1812 and RFC 2644.
If configured, incoming IP directed broadcast packets on this interface will be forwarded.
If this option is unset (default), incoming IP directed broadcast packets will not be forwarded.
set interfaces virtual-ethernet veth0 vif 10 ip enable-directed-broadcast
Define behavior for gratuitous ARP frames who’s IP is not already present in the ARP table. If configured create new entries in the ARP table.
Both replies and requests type gratuitous arp will trigger the ARP table to be updated, if this setting is on.
If the ARP table already contains the IP address of the gratuitous arp frame, the arp table will be updated regardless if this setting is on or off.
set interfaces virtual-ethernet veth0 vif 10 ip enable-arp-accept
Define different restriction levels for announcing the local source IP address from IP packets in ARP requests sent on interface.
Use any local address, configured on any interface if this is not set.
If configured, try to avoid local addresses that are not in the target’s subnet for this interface. This mode is useful when target hosts reachable via this interface require the source IP address in ARP requests to be part of their logical network configured on the receiving interface. When we generate the request we will check all our subnets that include the target IP and will preserve the source address if it is from such subnet. If there is no such subnet we select source address according to the rules for level 2.
set interfaces virtual-ethernet veth0 vif 10 ip enable-arp-announce
Define different modes for sending replies in response to received ARP requests that resolve local target IP addresses:
If configured, reply only if the target IP address is local address configured on the incoming interface.
If this option is unset (default), reply for any local target IP address, configured on any interface.
set interfaces virtual-ethernet veth0 vif 10 ip enable-arp-ignore
Use this command to enable proxy Address Resolution Protocol (ARP) on this interface. Proxy ARP allows an Ethernet interface to respond with its own MAC address to ARP requests for destination IP addresses on subnets attached to other interfaces on the system. Subsequent packets sent to those destination IP addresses are forwarded appropriately by the system.
Example:
set interfaces virtual-ethernet veth0 vif 10 ip enable-proxy-arp
Private VLAN proxy arp. Basically allow proxy arp replies back to the same interface (from which the ARP request/solicitation was received).
This is done to support (ethernet) switch features, like RFC 3069, where the individual ports are NOT allowed to communicate with each other, but they are allowed to talk to the upstream router. As described in RFC 3069, it is possible to allow these hosts to communicate through the upstream router by proxy_arp’ing.
Note
Does not need to be used together with proxy_arp.
This technology is known by different names:
In RFC 3069 it is called VLAN Aggregation
Cisco and Allied Telesyn call it Private VLAN
Hewlett-Packard call it Source-Port filtering or port-isolation
Ericsson call it MAC-Forced Forwarding (RFC Draft)
Enable policy for source validation by reversed path, as specified in RFC 3704. Current recommended practice in RFC 3704 is to enable strict mode to prevent IP spoofing from DDos attacks. If using asymmetric routing or other complicated routing, then loose mode is recommended.
strict: Each incoming packet is tested against the FIB and if the interface is not the best reverse path the packet check will fail. By default failed packets are discarded.
loose: Each incoming packet’s source address is also tested against the FIB and if the source address is not reachable via any interface the packet check will fail.
disable: No source validation
SLAAC RFC 4862. IPv6 hosts can configure themselves automatically when connected to an IPv6 network using the Neighbor Discovery Protocol via ICMPv6 router discovery messages. When first connected to a network, a host sends a link-local router solicitation multicast request for its configuration parameters; routers respond to such a request with a router advertisement packet that contains Internet Layer configuration parameters.
Note
This method automatically disables IPv6 traffic forwarding on the interface in question.
Example:
set interfaces virtual-ethernet veth0 vif 10 ipv6 address autoconf
EUI-64 as specified in RFC 4291 allows a host to assign iteslf a unique 64-Bit IPv6 address.
Example:
set interfaces virtual-ethernet veth0 vif 10 ipv6 address eui64 2001:db8:beef::/64
Do not assign a link-local IPv6 address to this interface.
Example:
set interfaces virtual-ethernet veth0 vif 10 ipv6 address no-default-link-local
Configure interface-specific Host/Router behaviour. If set, the interface will switch to host mode and IPv6 forwarding will be disabled on this interface.
Example:
set interfaces virtual-ethernet veth0 vif 10 ipv6 disable-forwarding
As Internet wide PMTU discovery rarely works, we sometimes need to clamp our TCP MSS value to a specific value. This is a field in the TCP options part of a SYN packet. By setting the MSS value, you are telling the remote side unequivocally ‘do not try to send me packets bigger than this value’.
Note
This command was introduced in VyOS 1.4 - it was previously called:
set firewall options interface <name> adjust-mss6 <value>
Hint
MSS value = MTU - 40 (IPv6 header) - 20 (TCP header), resulting in 1432 bytes on a 1492 byte MTU.
Instead of a numerical MSS value clamp-mss-to-pmtu can be used to automatically set the proper value.
Whether to accept DAD (Duplicate Address Detection).
0: Disable DAD
1: Enable DAD (default)
2: Enable DAD, and disable IPv6 operation if MAC-based duplicate link-local address has been found.
Example:
set interfaces virtual-ethernet veth0 vif 10 ipv6 accept-dad 2
The amount of Duplicate Address Detection probes to send.
Default: 1
Example:
set interfaces virtual-ethernet veth0 vif 10 ipv6 dup-addr-detect-transmits 5
Place interface in given VRF instance.
See also
There is an entire chapter about how to configure a VRF, please check this for additional information.
Example:
set interfaces virtual-ethernet veth0 vif 10 vrf red
DHCP(v6)
RFC 2131 states: The client MAY choose to explicitly provide the identifier through the ‘client identifier’ option. If the client supplies a ‘client identifier’, the client MUST use the same ‘client identifier’ in all subsequent messages, and the server MUST use that identifier to identify the client.
Example:
set interfaces virtual-ethernet veth0 vif 10 dhcp-options client-id 'foo-bar'
Instead of sending the real system hostname to the DHCP server, overwrite the host-name with this given-value.
Example:
set interfaces virtual-ethernet veth0 vif 10 dhcp-options host-name 'VyOS'
This option is used by some DHCP clients to identify the vendor type and possibly the configuration of a DHCP client. The information is a string of bytes whose contents are specific to the vendor and are not specified in a standard.
The vendor-class-id option can be used to request a specific class of vendor options from the server.
Example:
set interfaces virtual-ethernet veth0 vif 10 dhcp-options vendor-class-id 'VyOS'
Only request an address from the DHCP server but do not request a default gateway.
Example:
set interfaces virtual-ethernet veth0 vif 10 dhcp-options no-default-route
Set the distance for the default gateway sent by the DHCP server.
Example:
set interfaces virtual-ethernet veth0 vif 10 dhcp-options default-route-distance 220
Reject DHCP leases from a given address or range. This is useful when a modem gives a local IP when first starting.
address can be specified multiple times, e.g. 192.168.100.1 and/or 192.168.100.0/24
Example:
set interfaces virtual-ethernet veth0 vif 10 dhcp-options reject 192.168.100.0/24
This option is used by some DHCP clients as a way for users to specify identifying information to the client. This can be used in a similar way to the vendor-class-identifier option, but the value of the option is specified by the user, not the vendor.
Example:
set interfaces virtual-ethernet veth0 vif 10 dhcp-options user-class VyOS
The DHCP unique identifier (DUID) is used by a client to get an IP address from a DHCPv6 server. It has a 2-byte DUID type field, and a variable-length identifier field up to 128 bytes. Its actual length depends on its type. The server compares the DUID with its database and delivers configuration data (address, lease times, DNS servers, etc.) to the client.
set interfaces virtual-ethernet veth0 vif 10 duid '0e:00:00:01:00:01:27:71:db:f0:00:50:56:bf:c5:6d'
When no-release is specified, dhcp6c will send a release message on client exit to prevent losing an assigned address or prefix.
set interfaces virtual-ethernet veth0 vif 10 dhcpv6-options no-release
This statement specifies dhcp6c to only exchange informational configuration parameters with servers. A list of DNS server addresses is an example of such parameters. This statement is useful when the client does not need stateful configuration parameters such as IPv6 addresses or prefixes.
set interfaces virtual-ethernet veth0 vif 10 dhcpv6-options parameters-only
When rapid-commit is specified, dhcp6c will include a rapid-commit option in solicit messages and wait for an immediate reply instead of advertisements.
set interfaces virtual-ethernet veth0 vif 10 dhcpv6-options rapid-commit
Request only a temporary address and not form an IA_NA (Identity Association for Non-temporary Addresses) partnership.
set interfaces virtual-ethernet veth0 vif 10 dhcpv6-options temporary
DHCPv6 Prefix Delegation (PD)
VyOS 1.3 (equuleus) supports DHCPv6-PD (RFC 3633). DHCPv6 Prefix Delegation is supported by most ISPs who provide native IPv6 for consumers on fixed networks.
Some ISPs by default only delegate a /64 prefix. To request for a specific prefix size use this option to request for a bigger delegation for this pd <id>. This value is in the range from 32 - 64 so you could request up to a /32 prefix (if your ISP allows this) down to a /64 delegation.
The default value corresponds to 64.
To request a /56 prefix from your ISP use:
set interfaces virtual-ethernet veth0 vif 10 dhcpv6-options pd 0 length 56
Specify the interface address used locally on the interface where the prefix has been delegated to. ID must be a decimal integer.
It will be combined with the delegated prefix and the sla-id to form a complete interface address. The default is to use the EUI-64 address of the interface.
Example: Delegate a /64 prefix to interface eth8 which will use a local
address on this router of <prefix>::ffff, as the address 65534 will
correspond to ffff in hexadecimal notation.
set interfaces virtual-ethernet veth0 vif 10 dhcpv6-options pd 0 interface eth8 address 65534
Specify the identifier value of the site-level aggregator (SLA) on the interface. ID must be a decimal number greater then 0 which fits in the length of SLA IDs (see below).
Example: If ID is 1 and the client is delegated an IPv6 prefix 2001:db8:ffff::/48, dhcp6c will combine the two values into a single IPv6 prefix, 2001:db8:ffff:1::/64, and will configure the prefix on the specified interface.
set interfaces virtual-ethernet veth0 vif 10 dhcpv6-options pd 0 interface eth8 sla-id 1
QinQ (802.1ad)
Call for Contributions
This section needs improvements, examples and explanations.
Please take a look at the Contributing Guide for our Write Documentation.
IEEE 802.1ad was an Ethernet networking standard informally known as QinQ as an amendment to IEEE standard 802.1q VLAN interfaces as described above. 802.1ad was incorporated into the base 802.1q standard in 2011. The technique is also known as provider bridging, Stacked VLANs, or simply QinQ or Q-in-Q. “Q-in-Q” can for supported devices apply to C-tag stacking on C-tag (Ethernet Type = 0x8100).
The original 802.1q specification allows a single Virtual Local Area Network (VLAN) header to be inserted into an Ethernet frame. QinQ allows multiple VLAN tags to be inserted into a single frame, an essential capability for implementing Metro Ethernet network topologies. Just as QinQ extends 802.1Q, QinQ itself is extended by other Metro Ethernet protocols.
In a multiple VLAN header context, out of convenience the term “VLAN tag” or just “tag” for short is often used in place of “802.1q VLAN header”. QinQ allows multiple VLAN tags in an Ethernet frame; together these tags constitute a tag stack. When used in the context of an Ethernet frame, a QinQ frame is a frame that has 2 VLAN 802.1q headers (double-tagged).
In VyOS the terms vif-s and vif-c stand for the ethertype tags that
are used.
The inner tag is the tag which is closest to the payload portion of the frame. It is officially called C-TAG (customer tag, with ethertype 0x8100). The outer tag is the one closer/closest to the Ethernet header, its name is S-TAG (service tag with Ethernet Type = 0x88a8).
Configure interface <interface> with one or more interface addresses.
address can be specified multiple times as IPv4 and/or IPv6 address, e.g. 192.0.2.1/24 and/or 2001:db8::1/64
dhcp interface address is received by DHCP from a DHCP server on this segment.
dhcpv6 interface address is received by DHCPv6 from a DHCPv6 server on this segment.
Note
When using DHCP to retrieve IPv4 address and if local customizations are needed, they should be possible using the enter and exit hooks provided. The hook dirs are:
/config/scripts/dhcp-client/pre-hooks.d//config/scripts/dhcp-client/post-hooks.d/
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 address 192.0.2.1/24
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 address 2001:db8::1/64
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 address dhcp
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 address dhcpv6
Set a human readable, descriptive alias for this connection. Alias is used by
e.g. the show interfaces command or SNMP based monitoring tools.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 description 'This is an awesome interface running on VyOS'
Disable given <interface>. It will be placed in administratively down
(A/D) state.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 disable
Use this command to direct an interface to not detect any physical state changes on a link, for example, when the cable is unplugged.
Default is to detects physical link state changes.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 disable-link-detect
Configure user defined MAC address on given <interface>.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 mac '00:01:02:03:04:05'
Configure MTU on given <interface>. It is the size (in bytes) of the largest ethernet frame sent on this link.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 mtu 1600
As Internet wide PMTU discovery rarely works, we sometimes need to clamp our TCP MSS value to a specific value. This is a field in the TCP options part of a SYN packet. By setting the MSS value, you are telling the remote side unequivocally ‘do not try to send me packets bigger than this value’.
Note
This command was introduced in VyOS 1.4 - it was previously called:
set firewall options interface <name> adjust-mss <value>
Hint
MSS value = MTU - 20 (IP header) - 20 (TCP header), resulting in 1452 bytes on a 1492 byte MTU.
Instead of a numerical MSS value clamp-mss-to-pmtu can be used to automatically set the proper value.
Once a neighbor has been found, the entry is considered to be valid for at least for this specific time. An entry’s validity will be extended if it receives positive feedback from higher level protocols.
This defaults to 30 seconds.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip arp-cache-timeout 180
If set the kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load-balancing, does this behaviour cause problems.
If not set (default) allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP’d IP out that interface (therefore you must use source based routing for this to work).
In other words it allows control of which cards (usually 1) will respond to an arp request.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip disable-arp-filter
Configure interface-specific Host/Router behaviour. If set, the interface will switch to host mode and IPv6 forwarding will be disabled on this interface.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip disable-forwarding
Define different modes for IP directed broadcast forwarding as described in RFC 1812 and RFC 2644.
If configured, incoming IP directed broadcast packets on this interface will be forwarded.
If this option is unset (default), incoming IP directed broadcast packets will not be forwarded.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip enable-directed-broadcast
Define behavior for gratuitous ARP frames who’s IP is not already present in the ARP table. If configured create new entries in the ARP table.
Both replies and requests type gratuitous arp will trigger the ARP table to be updated, if this setting is on.
If the ARP table already contains the IP address of the gratuitous arp frame, the arp table will be updated regardless if this setting is on or off.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip enable-arp-accept
Define different restriction levels for announcing the local source IP address from IP packets in ARP requests sent on interface.
Use any local address, configured on any interface if this is not set.
If configured, try to avoid local addresses that are not in the target’s subnet for this interface. This mode is useful when target hosts reachable via this interface require the source IP address in ARP requests to be part of their logical network configured on the receiving interface. When we generate the request we will check all our subnets that include the target IP and will preserve the source address if it is from such subnet. If there is no such subnet we select source address according to the rules for level 2.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip enable-arp-announce
Define different modes for sending replies in response to received ARP requests that resolve local target IP addresses:
If configured, reply only if the target IP address is local address configured on the incoming interface.
If this option is unset (default), reply for any local target IP address, configured on any interface.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip enable-arp-ignore
Use this command to enable proxy Address Resolution Protocol (ARP) on this interface. Proxy ARP allows an Ethernet interface to respond with its own MAC address to ARP requests for destination IP addresses on subnets attached to other interfaces on the system. Subsequent packets sent to those destination IP addresses are forwarded appropriately by the system.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ip enable-proxy-arp
Private VLAN proxy arp. Basically allow proxy arp replies back to the same interface (from which the ARP request/solicitation was received).
This is done to support (ethernet) switch features, like RFC 3069, where the individual ports are NOT allowed to communicate with each other, but they are allowed to talk to the upstream router. As described in RFC 3069, it is possible to allow these hosts to communicate through the upstream router by proxy_arp’ing.
Note
Does not need to be used together with proxy_arp.
This technology is known by different names:
In RFC 3069 it is called VLAN Aggregation
Cisco and Allied Telesyn call it Private VLAN
Hewlett-Packard call it Source-Port filtering or port-isolation
Ericsson call it MAC-Forced Forwarding (RFC Draft)
Enable policy for source validation by reversed path, as specified in RFC 3704. Current recommended practice in RFC 3704 is to enable strict mode to prevent IP spoofing from DDos attacks. If using asymmetric routing or other complicated routing, then loose mode is recommended.
strict: Each incoming packet is tested against the FIB and if the interface is not the best reverse path the packet check will fail. By default failed packets are discarded.
loose: Each incoming packet’s source address is also tested against the FIB and if the source address is not reachable via any interface the packet check will fail.
disable: No source validation
SLAAC RFC 4862. IPv6 hosts can configure themselves automatically when connected to an IPv6 network using the Neighbor Discovery Protocol via ICMPv6 router discovery messages. When first connected to a network, a host sends a link-local router solicitation multicast request for its configuration parameters; routers respond to such a request with a router advertisement packet that contains Internet Layer configuration parameters.
Note
This method automatically disables IPv6 traffic forwarding on the interface in question.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ipv6 address autoconf
EUI-64 as specified in RFC 4291 allows a host to assign iteslf a unique 64-Bit IPv6 address.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ipv6 address eui64 2001:db8:beef::/64
Do not assign a link-local IPv6 address to this interface.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ipv6 address no-default-link-local
Configure interface-specific Host/Router behaviour. If set, the interface will switch to host mode and IPv6 forwarding will be disabled on this interface.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ipv6 disable-forwarding
As Internet wide PMTU discovery rarely works, we sometimes need to clamp our TCP MSS value to a specific value. This is a field in the TCP options part of a SYN packet. By setting the MSS value, you are telling the remote side unequivocally ‘do not try to send me packets bigger than this value’.
Note
This command was introduced in VyOS 1.4 - it was previously called:
set firewall options interface <name> adjust-mss6 <value>
Hint
MSS value = MTU - 40 (IPv6 header) - 20 (TCP header), resulting in 1432 bytes on a 1492 byte MTU.
Instead of a numerical MSS value clamp-mss-to-pmtu can be used to automatically set the proper value.
Whether to accept DAD (Duplicate Address Detection).
0: Disable DAD
1: Enable DAD (default)
2: Enable DAD, and disable IPv6 operation if MAC-based duplicate link-local address has been found.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ipv6 accept-dad 2
The amount of Duplicate Address Detection probes to send.
Default: 1
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 ipv6 dup-addr-detect-transmits 5
Place interface in given VRF instance.
See also
There is an entire chapter about how to configure a VRF, please check this for additional information.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 vrf red
DHCP(v6)
RFC 2131 states: The client MAY choose to explicitly provide the identifier through the ‘client identifier’ option. If the client supplies a ‘client identifier’, the client MUST use the same ‘client identifier’ in all subsequent messages, and the server MUST use that identifier to identify the client.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcp-options client-id 'foo-bar'
Instead of sending the real system hostname to the DHCP server, overwrite the host-name with this given-value.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcp-options host-name 'VyOS'
This option is used by some DHCP clients to identify the vendor type and possibly the configuration of a DHCP client. The information is a string of bytes whose contents are specific to the vendor and are not specified in a standard.
The vendor-class-id option can be used to request a specific class of vendor options from the server.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcp-options vendor-class-id 'VyOS'
Only request an address from the DHCP server but do not request a default gateway.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcp-options no-default-route
Set the distance for the default gateway sent by the DHCP server.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcp-options default-route-distance 220
Reject DHCP leases from a given address or range. This is useful when a modem gives a local IP when first starting.
address can be specified multiple times, e.g. 192.168.100.1 and/or 192.168.100.0/24
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcp-options reject 192.168.100.0/24
This option is used by some DHCP clients as a way for users to specify identifying information to the client. This can be used in a similar way to the vendor-class-identifier option, but the value of the option is specified by the user, not the vendor.
Example:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcp-options user-class VyOS
The DHCP unique identifier (DUID) is used by a client to get an IP address from a DHCPv6 server. It has a 2-byte DUID type field, and a variable-length identifier field up to 128 bytes. Its actual length depends on its type. The server compares the DUID with its database and delivers configuration data (address, lease times, DNS servers, etc.) to the client.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 duid '0e:00:00:01:00:01:27:71:db:f0:00:50:56:bf:c5:6d'
When no-release is specified, dhcp6c will send a release message on client exit to prevent losing an assigned address or prefix.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcpv6-options no-release
This statement specifies dhcp6c to only exchange informational configuration parameters with servers. A list of DNS server addresses is an example of such parameters. This statement is useful when the client does not need stateful configuration parameters such as IPv6 addresses or prefixes.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcpv6-options parameters-only
When rapid-commit is specified, dhcp6c will include a rapid-commit option in solicit messages and wait for an immediate reply instead of advertisements.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcpv6-options rapid-commit
Request only a temporary address and not form an IA_NA (Identity Association for Non-temporary Addresses) partnership.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcpv6-options temporary
DHCPv6 Prefix Delegation (PD)
VyOS 1.3 (equuleus) supports DHCPv6-PD (RFC 3633). DHCPv6 Prefix Delegation is supported by most ISPs who provide native IPv6 for consumers on fixed networks.
Some ISPs by default only delegate a /64 prefix. To request for a specific prefix size use this option to request for a bigger delegation for this pd <id>. This value is in the range from 32 - 64 so you could request up to a /32 prefix (if your ISP allows this) down to a /64 delegation.
The default value corresponds to 64.
To request a /56 prefix from your ISP use:
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcpv6-options pd 0 length 56
Specify the interface address used locally on the interface where the prefix has been delegated to. ID must be a decimal integer.
It will be combined with the delegated prefix and the sla-id to form a complete interface address. The default is to use the EUI-64 address of the interface.
Example: Delegate a /64 prefix to interface eth8 which will use a local
address on this router of <prefix>::ffff, as the address 65534 will
correspond to ffff in hexadecimal notation.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcpv6-options pd 0 interface eth8 address 65534
Specify the identifier value of the site-level aggregator (SLA) on the interface. ID must be a decimal number greater then 0 which fits in the length of SLA IDs (see below).
Example: If ID is 1 and the client is delegated an IPv6 prefix 2001:db8:ffff::/48, dhcp6c will combine the two values into a single IPv6 prefix, 2001:db8:ffff:1::/64, and will configure the prefix on the specified interface.
set interfaces virtual-ethernet veth0 vif-s 1000 vif-c 20 dhcpv6-options pd 0 interface eth8 sla-id 1
Disable given <interface>. It will be placed in administratively down
(A/D) state.
Example:
set interfaces virtual-ethernet veth0 disable
Place interface in given VRF instance.
See also
There is an entire chapter about how to configure a VRF, please check this for additional information.
Example:
set interfaces virtual-ethernet veth0 vrf red
Operation
Show brief interface information.
vyos@vyos:~$ show interfaces virtual-ethernet
Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface IP Address S/L Description
--------- ---------- --- -----------
veth10 100.64.0.0/31 u/u
veth11 100.64.0.1/31 u/u
Show detailed information on given <interface>
vyos@vyos:~$ show interfaces virtual-ethernet veth11
10: veth11@veth10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master red state UP group default qlen 1000
link/ether b2:7b:df:47:e9:11 brd ff:ff:ff:ff:ff:ff
inet 100.64.0.1/31 scope global veth11
valid_lft forever preferred_lft forever
inet6 fe80::b07b:dfff:fe47:e911/64 scope link
valid_lft forever preferred_lft forever
RX: bytes packets errors dropped overrun mcast
0 0 0 0 0 0
TX: bytes packets errors dropped carrier collisions
1369707 4267 0 0 0 0
Example
Interconnect the global VRF with vrf “red” using the veth10 <-> veth 11 pair
set interfaces virtual-ethernet veth10 address '100.64.0.0/31'
set interfaces virtual-ethernet veth10 peer-name 'veth11'
set interfaces virtual-ethernet veth11 address '100.64.0.1/31'
set interfaces virtual-ethernet veth11 peer-name 'veth10'
set interfaces virtual-ethernet veth11 vrf 'red'
set vrf name red table '1000'
vyos@vyos:~$ ping 100.64.0.1
PING 100.64.0.1 (100.64.0.1) 56(84) bytes of data.
64 bytes from 100.64.0.1: icmp_seq=1 ttl=64 time=0.080 ms
64 bytes from 100.64.0.1: icmp_seq=2 ttl=64 time=0.119 ms