The Linux kernel universally distinguishes between two types of software network interfaces:
wlan19, .. always represent an actual network hardware device such as a NIC, WNIC or some other kind of Modem. As soon as the device driver is loaded into the Kernel a corresponding physical network interface becomes present and available.
Any physical network interface is a named software representation by the operating system to the user to enable him to configure the hardware network device and also to integrate it into programs and scripts.
teql0, .. are virtual network interfaces that do NOT represent an existent hardware device but are linked to one (otherwise they would be useless). Virtual network interfaces were invented to give the system administrator maximum flexibility when configuring a Linux-based operating system. A virtual network interface is generally associated with a physical network interface (eth6) or another virtual interface (eth6.9) or be stand alone such as the loopback interface
|UCI is a small C utility designed to centralize configuration in OpenWrt.
UCI creates an abstraction layer for configuring network interfaces:
The OpenWrt default configuration is explained in …
Most GNU/Linux distributions offer various software packages in their repositories which contain standard Unix networking tools for controlling the network subsystem of the Linux kernel; they serve the task of configuring network interfaces, routing tables, managing the ARP table, and so on. In Debian multiple such tools are combined into packages, e.g. net-tools, iproute2, vlan, bridge-utils, wireless-tools, iw and some more.
The utilities contained in the “net-tools”-suite are old and deprecated. The ones contained in the "iproute2"-suite communicate with the Linux kernel via the (rt)netlink interface, providing advanced features not available through the legacy "net-tools"- commands
route. See e.g. iproute2 or net-tools VS iproute2) for a comparison.
| In the OpenWrt software package repositories networking utilities are available as separate
| || ||Purpose|
| || ||network device configuration|
| ||protocol IPv4 or IPv6 address management on a device|
| ||protocol address label management, label configuration for protocol address selection|
| || establish static (aka unmanaged) L2TPv3 Ethernet tunnels.
For unmanaged tunnels, there is no L2TP control protocol so no userspace daemon is required - tunnels are manually created by issuing commands at a local system and at a remote peer.
L2TPv3 is suitable for Layer-2 tunneling. Static tunnels are useful to establish network links across IP networks when the tunnels are fixed. L2TPv3 tunnels can carry data of more than one session. Each session is identified by a session_id and its parent tunnel's tunnel_id. A tunnel must be created before a session can be created in the tunnel.
When creating an L2TP tunnel, the IP address of the remote peer is specified, which can be either an IPv4 or IPv6 address. The local IP address to be used to reach the peer must also be specified. This is the address on which the local system will listen for and accept received L2TP data packets from the peer.
L2TPv3 defines two packet encapsulation formats: UDP or IP. UDP encapsulation is most common. IP encapsulation uses a dedicated IP protocol value to carry L2TP data without the overhead of UDP. Use IP encapsulation only when there are no NAT devices or firewalls in the network path.
When an L2TPv3 Ethernet session is created, a virtual network interface is created for the session, which must then be configured and brought up, just like any other network interface. When data is passed through the interface, it is carried over the L2TP tunnel to the peer. By configuring the system's routing tables or adding the interface to a bridge, the L2TP interface is like a virtual wire (pseudowire) connected to the peer.
Establishing an unmanaged L2TPv3 Ethernet pseudowire involves manually creating L2TP contexts on the local system and at the peer. Parameters used at each site must correspond or no data will be passed. No consistency checks are possible since there is no control protocol used to establish unmanaged L2TP tunnels. Once the virtual network interface of a given L2TP session is configured and enabled, data can be transmitted, even if the peer isn't yet configured. If the peer isn't configured, the L2TP data packets will be discarded by the peer.
To establish an unmanaged L2TP tunnel, use
Note that unmanaged tunnels carry only Ethernet frames. If you need to carry PPP traffic (L2TPv2) or your peer doesn't support unmanaged L2TPv3 tunnels, you will need an L2TP server which implements the L2TP control protocol. The L2TP control protocol allows dynamic L2TP tunnels and sessions to be established and provides for detecting and acting upon network failures.
| ||neighbour/arp tables management, ARP or NDISC cache entry|
| ||network configuration monitoring
utility can monitor IPv4 and IPv6 parameters (see
| || process network namespace management
A network namespace is logically another copy of the network stack, with its own routes, firewall rules, and network devices.
| || neighbour table configuration
controls the parameters for the neighbour tables
| || routing table management. Configuration files are:
| ||routing policy database management|
| ||multicast addresses management|
| ||multicast routing cache management|
| ||tunnel over IP configuration|
| || state monitoring, see
| ||setting xfrm, framework for IPsec protocol|
| || used to manipulate entries in the Linux kernel that keep TCP information for IPv4 and IPv6 destinations. The entries are created when TCP sockets want to share information for destinations and are stored in a cache keyed by the destination address. The saved information may include values for metrics (initially obtained from routes), recent TSVAL for TIME-WAIT recycling purposes, state for the Fast Open feature, etc. For performance reasons the cache can not grow above configured limit and the older entries are replaced with fresh information, sometimes reclaimed and used for new destinations. The kernel never removes entries, they can be flushed only with this tool.
| ||Listens to and monitors RTnetlink|
| || Set of helper scripts you can use instead of
| || utility to dump socket statistics. It allows showing information similar to the deprecated
| ||show / manipulate traffic control settings. tc is used to configure the Network packet scheduler of the Linux kernel|
| || Unified Linux network statistics
A generalized and more feature-complete replacement for the old
| ||userspace arp daemon|
| ||VLAN (IEEE 802.1q) configuration program. Allows you to create and remove VLAN−devices on a VLAN enabled Linux kernel. VLAN−devices are virtual Ethernet devices which represents the virtual lans on the physical lan|
| ||Linux Ethernet bridge administration|
| || show / manipulate bridge addresses and devices;
| ||show / manipulate wireless devices and their configuration|
| || iwinfo is a CLI frontend to the library
|Purpose|| ||replaced with|
| IPv4/IPv6 address|
and link configuration
|Routing tables|| ||
|Manipulate the kernel's ARP table. Add, delete an entry, or to dump the entire cache|| ||
|Adds, changes, deletes and shows an interface's tunnels|| ||
|Adds, deletes and shows an interface's multicast addresses|| ||
|Report network connections, routing tables, and interface statistics|| ||
|Manipulate the kernel's RARP table|| |
|Name network interfaces based on MAC addresses|| |
|Fine tune the PLIP device parameters, to improve its performance|| |
|Attaches a network interface to a serial line. This allows to use normal terminal lines for point-to-point links to other computers.|| |
|Checks or sets the status of a network interface's Media Independent Interface (MII) unit|| |
|configure a wireless network interface|| ||
|Display Wireless Events generated by drivers and setting changes|| ||
|Report ESSID, NWID or AP/Cell Address of wireless network|| ||
|Get more detailed wireless information from a wireless interface|| ||
|configure optionals (private) parameters of a wireless network interface|| ||
|Get wireless statistics from specific nodes|| ||