interfaces(5) # NAME */etc/network/interfaces* - interface configuration database # DESCRIPTION The */etc/network/interfaces* file is used to specify how network interfaces are configured. The file is processed by *ifquery*(8), *ifup*(8) and *ifdown*(8) to introspect and change system state. In most cases, syntax from legacy implementations is supported as well, but that syntax is not discussed here. # FILE SYNTAX The interface configuration database is composed of a series of stanzas. Hash symbols designate comments, which are ignored by the system. A stanza is a collection of triples, where a triple is a key and value combination that is related to an *object*. Triples which are not associated with an *object* are considered to be part of the root of the configuration tree. The following is a simple example of a stanza: ``` auto eth0 iface eth0 address 203.0.113.2/24 gateway 203.0.113.1 ``` This stanza defines an interface named *eth0* which is configured with an address of *203.0.113.2* and gateway of *203.0.113.1*. # SUPPORTED KEYWORDS FOR UNASSOCIATED TRIPLES *auto* _object_ Designates that _object_ should be automatically configured by the system when appropriate. *iface* _object_ Begins a new declaration for _object_. Any child keyword associated with the declaration will be stored inside _object_. *template* _object_ Begins a new declaration for _object_, like *iface*, except that _object_ is defined as a *template*. # SUPPORTED KEYWORDS FOR OBJECT TRIPLES Any keyword may be used inside an interface declaration block, but the system will only respond to certain keywords by default: *address* _address_ Associates an IPv4 or IPv6 address in CIDR notation with the parent interface. *gateway* _address_ Associates an IPv4 or IPv6 address with the parent interface for use as a default route (gateway). *netmask* _netmask_ Associates a fallback netmask with the parent interface for addresses which do not have a CIDR length set. This option is for backwards compatibility and should not be used in new deployments. *link-type* _link-type_ Denotes the link-type of the interface. When set to _dummy_, the interface is created as a virtual dummy interfaces. When set to _veth_ the interface is created as virtual veth interface (pair). *veth-peer-name* _peer-name_ Denotes the name of the veth peer interfaces. If not set the kernel will name the veth peer interface as _vethN_ with N being an integer number. *alias* _alias_ Sets the given alias on the interface. *requires* _interfaces_... Designates one or more required interfaces that must be brought up before configuration of the parent interface. Interfaces associated with the parent are taken down at the same time as the parent. *inherit* _object_ Designates that the configured interface should inherit configuration data from _object_. Normally _object_ must be a *template*. *use* _option_ Designates that an option should be used. See _OPTIONS_ section for more information on options. *pre-down* _command_ Runs _command_ before taking the interface down. *down* _command_ Runs _command_ when the interface is taken down. *post-down* _command_ Runs _command_ after taking the interface down. *pre-up* _command_ Runs _command_ before bringing the interface up. *up* _command_ Runs _command_ when the interface is brought up. *post-up* _command_ Runs _command_ after bringing the interface up. Additional packages such as *bonding*, *bridge*, *tunnel*, *vrf* and *vxlan* add additional keywords to this vocabulary. # OPTIONS The *use* keyword designates that an _option_ should be used. This system is extendable by additional packages, but the most common options are: *batman* The interface is a B.A.T.M.A.N. adv. mesh interface. Configuration of B.A.T.M.A.N. adv. interfaces requires the *batctl* untiliy to be installed. *bond* The interface is a bonded interface. Configuration of bonded interfaces requires the *bonding* package to be installed. *bridge* The interface is an ethernet bridge. Configuration of ethernet bridges requires the *bridge* package to be installed. *dhcp* Use a DHCP client to learn the IPv4 address of an interface. *loopback* Designates the interface as a loopback device. *tunnel* The interface is a tunnel. Configuration of tunnels requires the *tunnel* package to be installed. *vrf* The interface is a VRF. Configuration of VRFs requires the *vrf* package to be installed. *vxlan* The interface is a Virtual Extensible LAN (VXLAN) tunnel endpoint. Check *interfaces-