definition du protocole dhcp

DHCP: Definition

Do you know that anonymity on social networks doesn’t protect you that much? Are you aware that anyone can find you using your IP address? Do you know of the existence of a temporary nomination procedure between the different devices on a home network so that communication between them can take place? Today, we are taking a close look at the identifier made up of a series of numbers. This article talks about the assignment protocol commonly called DHCP. Follow the leader.

The Dynamic Host Configuration Protocol

DHCP is the acronym for Dynamic Host Configuration Protocol. This English term is commonly used by network technicians and IT professionals, but everyone should know it. It indicates the rule for assigning a unique identification to each piece of equipment. The DHCP address is like a name that allows you to distinguish a device from the rest of the computer equipment. As with the telephone, an IP (Internet Protocol) address should be associated with a single terminal which can be a computer, a Smartphone or other connected equipment.

The DHCP protocol is therefore essential so that all assigned identifiers are compatible. This standard helps monitor the evolution of PCs and peripherals attached to a network. It allows you to connect equipment to the system or check its presence. Regardless, there are two distinct categories of devices. Alongside classic workstations, there are servers. They don’t follow the same rule. The first have a dynamic identifier automatically assigned while the other will have a fixed IP address which can be manually changed.

The history of DHCP begins long before the advent of the Web

In 1984, it was necessary to create a new interconnection protocol between machines. It was first called RARP (Reverse Address Resolution Protocol). This technology makes it possible to identify each PC. The IETF (Internet Engineering Task Force) was the Web standards body still in its infancy. Diskless workstations did not have an operating system. The OS was then downloaded from a central server each time it was started. As there were several interconnected machines, addresses had to be assigned.

Too complicated, the RARP protocol is abandoned. In 1985, it was replaced by the Bootstrap Protocol (BOOTP). The latter automatically gives addresses not on one, but several networks. The DHCP identifier is a revolution in its time. Dynamic granting was constantly improved in the 90s. In addition to PCs, peripherals also obtain their IP codes. Since 1993, DHCP has become the standard when there are several devices connected to each other. It is mainly available in operating systems, including Windows Server.

Complex and dynamic operation

At home, the DHCP protocol is managed by the Internet service provider’s box. Address assignment is carried out at the LAN level. The identifier is temporary in accordance with a lease system, hence the D in Dynamic Host Configuration Protocol. For small professional structures such as a start-up (SME), DHCP addresses are distributed at the level of a router. Larger companies need a special server.

A DHCP server also manages the connection with machines external to the home network. It controls the gateway, a sort of tunnel that provides connection to the entire Internet. Each time the device is powered on, a so-called DHCPDISCOVER request, or a DHCPOFFER signal depending on the transmitter, is exchanged between the devices and the servers. If the assigned IP address is OK, the affected device sends a DHCPREQUEST message to the DHCP service. An ACK validates the identifier throughout the system. As a reminder, it is temporary. In the event of a problem, a NACK report is issued.

Proper configuration is required

Configuring DHCP was quite a job in the past. Nowadays, Plug and Play devices do not need much specific manipulation to be recognized by other equipment. That said, the use of fixed IP addresses and DHCP identifiers is still relevant. The ideal would be to configure everything manually. This allows you to adjust the speed of the network and properly calibrate the gateway for the intended tasks. If you don’t understand anything, just remember that DHCP is configured depending on the situation. The more devices there are, the more complex it will be and require the intervention of a network technician.

It is recommended to specify one outgoing and one incoming IP address during configuration. The DHCP setting also requires a subnet mask. This allows you to have extensions of the unique fixed identifier to access the Internet. Often, it is necessary to determine the length of the lease mentioned above. Then, it is preferable to indicate the default gateway, the primary and secondary DNS server. The latter manages the DHCP protocol.

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IP and DHCP addresses

DHCP identifiers avoid discord between different devices on the same network. That said, the fixed IP address is important. Moreover, any beginner technician can mix them. This kind of maneuver is as useless as it is dangerous. It would be even more tolerable not to touch DHCP protocols. In a pinch, the static IP address can be generated remotely by a third party. Many do it to circumvent controls.

The mission of DHCP is to connect a device to an Ethernet network connection. At the same time, it allows you to configure each device for Internet access. DHCP addresses are temporarily assigned and become free again after the lease period, which the technician can specify himself. To recognize the status of a terminal, you must enter the “ipconfig” command from the Windows menu. What should be the displayed IP address then changes over time.

The DHCP identifier is a dynamic IP address. Internet service providers (ISPs) rely on this technology in parallel with the TCP IP protocol. The latter also manages network communication between computers. Unless you want to keep a fixed IP, this number is likely to change over time. Under Windows, a malfunction of the HDCP server is quickly compensated by the APIPA system. Which allows the PC to control a peripheral.

What is DHCP?

It is absolutely necessary to have a communications protocol or network protocol such as DHCP, or Dynamic Host Configuration Protocol.
Dynamic Host Configuration Protocol is usually used to translate it to another language.

You need to make sure that the IP settings are configured automatically.

The Dynamic Host Configuration Protocol (DHCP) must ensure the automatic configuration of the IP parameters of a machine or station.
It provides it with an effective IP address and allows it to be configured in two ways:

Addresses such as the default gateway, DNS servers, NBNS servers (which Microsoft refers to as WINS servers), and other information are required.

The DHCP protocol addresses a number of shortcomings of the IP protocol, including:

Operating computers may choose to use an address from the address space because it centralizes parameter changes, which it sends back to stations at boot time, and it centralizes parameter changes.

A potentially expensive purchase that should only be made by major networks

Purchasing a computer to serve as a DHCP server can be prohibitive, with only large businesses and government organizations able to afford such an investment.
Therefore, routers are increasingly used as a substitute for DHCP servers by households and small and medium-sized businesses (SMEs).

What is DHCP and how does it work?

This involves assigning IP addresses and configuring other data in a fully automated manner.

DHCP and broadcast are two protocols used.

dhcp protocol

When a machine boots, it sends a broadcast packet to the local network’s DHCP server, informing it of its presence.
The DHCP server then sends a second broadcast packet containing the information the client needs to complete its request.
Therefore, the DHCP server, which is the sole owner of a fixed IP address, is responsible for distributing the different IP addresses throughout the network environment.

Based on BOOTP, or Bootstrap Protocol, the procedure determines the IP address of a machine that does not have a hard drive or a network connection.

Here are the different variants of IP packets:

In addition to DHCPRELEASE, which allows the client to release its own IP address, DHCPDISCOVER, which is used to discover available DHCP servers, DHCPOFFER, which responds to a DHCPDISCOVER packet with the first parameters, and DHCPNAK, which notifies the client Whether its network configuration is incorrect or its lease has expired, there are several other protocols.

The DHCPREQUEST corresponds to a request from the client to extend its lease, the DHCPINFORM corresponds to a request from the client to request local parameters, and the DHCPACK corresponds to a response from the server to the client request.
It contains parameters as well as the client’s IP address, as well as the DHCPDECLINE, which is used by the client to notify the server that the specified address is in use.

What is the purpose of the DHCP server?

DHCP is a network protocol that allows automatic configuration and assignment of IP addresses to other devices on the network.
It significantly reduces the need for human intervention while providing economies of scale.

The effectiveness of centralized administration

DHCP is a protocol that centralizes and automatically manages addresses.

Distribution of addresses and other information

The DHCP server is responsible for assigning IP addresses to each computer on the network.
It also has the advantage of broadcasting a large amount of information on the network.
Of course, nothing stops the network administrator from assigning fixed IP addresses to other machines that are outside the IP address range provided by the DHCP server.

It is necessary for the administration of large networks.