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3.1 Link

The (ip link) module introduces procedures to access and modify the network links on your machine. They are equivalent to the ip link family of commands, from iproute2.

Datatype: <link> ¶

Datatype representing the status of a network link.

get-links print-link

<link> make-link link? link-name link-id link-type link-flags link-mtu link-qdisc link-state link-mode link-group link-qlen link-addr link-brd

name

Name of the link, such as "enp1s0".

id

Index of the link, a unique number used to identify the link.

type

Type of the link, as an integer.

flags

Flags associated with the device, as a list of symbols, such as '(UP LOOPBACK).

mtu

MTU of the link, as an integer.

qdisc

Queuing discipline of the link, as a string, such as "noqueue".

state

State of the link, as an integer. Use int->operstate from (netlink constant) to get a symbol, such as IF_OPER_UP.

mode

Mode of the link. 0 means DORMANT, 1 means DEFAULT.

group

Identifier of the group it belongs to. 0 for default.

qlen

Size of the queue.

addr

Ethernet address of the link, as a string.

brd

Broadcast (ethernet) address of the link, as a string.

Scheme Procedure: get-links ¶

Returns the list of existing links in the system, as a list of <link> objects.

Scheme Procedure: wait-for-link name [#:blocking? #t] ¶

Wait until a link called name (a string such as "ens3") shows up.

When blocking? is false, use a non-blocking socket and cooperate via current-read-waiter—useful when using Fibers.

Sceme Procedure: print-link link ¶

Display link on the standard output, using a format similar to ip link from iproute2.

Scheme Procedure: link-set device [#:up #f] [#:down #f] [#:type #f] [#:arp-on #f] [#:arp-off #f] [#:dynamic-on #f] [#:dynamic-off #f] [#:multicast-on #f] [#:multicast-off #f] [#:allmulticast-on #f] [#:allmulticast-off #f] [#:promisc-on #f] [#:promisc-off #f] [#:trailers-on #f] [#:trailers-off #f] [#:carrier-on #f] [#:carrier-off #f] [#:txqueuelen #f] [#:name #f] [#:address #f] [#:broadcast #f] [#:mtu #f] [#:netns #f] ¶

Modify an existing link and set its flags and attributes to the ones specified by the various keywords. When a keyword is omited, the corresponding attribute is not changed.

device can be a device index (as a number) or a device name (as a string).

Do not set #:up and #:down at the same time. Do not set *-on and *-off at the same time.

Scheme Procedure: link-show [#:device #f] [#:group #f] [#:up #f] [#:master #f] [#:vrf #f] [#:type #f] ¶

Print the set of devices on standard output. Setting any of the keyword to a non-false value will filter the results to only show results that match the corresponding value. You may set more than one keyword.

Scheme Procedure: link-add name type [#:type-args '()] ¶

Add a new link with given name and type. Additional arguments can be passed to control the state of the link at creation. type-args is an association list containing additional values for the given type.

When type is "vlan", type-args can contain a number associated with 'id: the VLAN id to be created and a link name associated with "link": the name of the link on which the vlan is created.

The following is an example in which we create a new vlan link:

;; same as "ip l add link eth0 name eth0.7 type vlan id 7"
(link-add "eth0.7" "vlan" #:type-args '((id . 7) (link . "eth0")))

When type is "veth", type-args can contain a string associated with 'peer: the name of the peer.

The following is an example in which we create a new veth (virtual ethernet) pair and give them a name:

;; same as "ip l add v0p0 type veth peer v0p1"
(link-add "v0p0" "veth" #:type-args '((peer . "v0p1")))

Scheme Procedure: link-del device ¶

Delete a link. device can contain the name of the link, as a string, or its index, as a number.