What is DHCP?

DHCP (Dynamic Host Configuration Protocol) is a client-server network protocol that automatically assigns IP addresses within a set range. The DHCP server assigns IP addresses as they become free or unused by other members of the network. To achieve its goal a DHCP server can assign IP addresses as follows: Manual or static assignment: assigns an IP address to a specific machine. Automatic assignment: assigns an IP address to a client machine the first time it makes the request to the DHCP server and until the client releases it. And the third way to assign an IP address by a DHCP server is dynamic assignment.

So, let’s start.

Configuring DHCP Server on Rocky Linux 8 / AlmaLinux OS 8 / CentOS 8

Before we start we need to make sure that the server is fully up to date. So, connect to it and update it.

sudo dnf update

Set a static IP address on Rocky Linux 8 / AlmaLinux OS 8 / CentOS 8

The DHCP server must have a static IP address. This is important for the host to be able to do the process well. So, this is our first step.

If you need to know How to set a static IP address on Rocky Linux 8 / AlmaLinux OS 8 / CentOS 8 then you can do it through the post we have prepared for you.

After that, you can continue

Configuring the DHCP server

The package that gives us the ability to deploy the server is dhcp-server So we have to install it

sudo dnf install dhcp-server

The package is fairly lightweight so the installation can be done quickly.

Now we have to edit the server configuration file. The file in question is /etc/dhcp/dhcpd.conf but before editing it create a backup

sudo cp /etc/dhcp/dhcpd.conf /etc/dhcpp/dhcpd.confl.bak

Now proceed to edit it with your favorite text editor. I use nano but you can use vi or vim.

sudo nano /etc/dhcp/dhcpd.conf

Now add the following

default-lease-time 900;
max-lease-time 10800;
ddns-update-style none;
authoritative;
subnet 192.168.20.0 netmask 255.255.255.0 {
  range 192.168.20.10 192.168.20.200;
  option routers 192.168.20.1;
  option subnet-mask 255.255.255.0;
  option domain-name-servers 192.168.20.1;

}

Remember that all these values have to be modified. In this case, I will use some example values.

Thanks to the default-lease-time option we will be able to define how long the DHCP server will reserve an address. While the max-lease-time option will define the maximum. In this case, I have set 900 seconds or 15 minutes for default-lease-time and 10800 minutes or 3 hours for max-lease-time.

Now comes the vital part of the subnet configuration.

In this case, the subnet to configure is 192.168.20.0 and the mask is 255.255.255.0. With the range option you define the range of IP addresses to assign. And with the option router option you can define the default gateway. The subnet mask assignment to each host is defined by the option subnet-mask option. Finally, option domain-name-servers defines the DNS servers to assign to each host.

Finally, when you are done editing the file, save your changes and close the editor.

Now enable and start the option domain-name-servers service.

sudo systemctl start dhcpd
sudo systemctl enable dhcpd

You can check the status of the service,

sudo systemctl status dhcpd

In order for the dhcp service to work properly, you need to open UDP port 67 on your firewall.

Now you just need to configure the network on your client computers for this configuration.

Conclusion

A DHCP server is a simple thing to do, however, it is good to have knowledge about your network to do it correctly.

So, enjoy it!

The post How to configure DHCP Server on RockyLinux 8 / AlmaLinux OS 8 / CentOS 8? appeared first on Linux Windows and android Tutorials.

DHCP (Dynamic Host Configuration Protocol) is a client-server network protocol that automatically assigns IP addresses within a set range. The DHCP server assigns IP addresses as they become free or unused by other members of the network.

To achieve its goal a DHCP server can assign IP addresses as follows:

• Manual or static assignment: assigns an IP address to a specific machine.
• Automatic assignment: assigns an IP address to a client machine the first time it makes the request to the DHCP server and until the client releases it.
• And the third way to assign an IP address by a DHCP server is dynamic assignment.

So, let’s start.

0. What I will do

First of all, I’ll explain to you what I’m going to do in this post.

Obviously, the first step is to install the DHCP network service. Then, I will teach you how to work with the systemd service.

At the end of this, we will define a range of IP addresses to be assigned automatically and finally, I will teach you how to configure the DHCP service to assign static addresses to the network nodes.

So this is the menu.

1. Install DHCP package

Installing DHCP is something anyone can do because it is a service that is in the official repositories of most Linux distributions. In this case, the tutorial is developed on both Debian 10/ and Debian 9, so a command is enough to install it:

:~$ su
:~# apt install isc-dhcp-server

Next, it is a good idea to enable DHCP to start at the system booting. To do that type:

:~# systemctl enable isc-dhcp-server

So, let’s configure DHCP.

2. Configure the DHCP server

It’s really easy to set up at least a basic DHCP server. All its configuration is in the file /etc/dhcp/dhcpd.conf. So, you have to edit it. But first, back up the file.

:~# cp /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.bak
:~# nano /etc/dhcp/dhcp.conf

When you open the file for the first time, you will see that it has loaded by default some species of configuration templates that you can modify to your liking.

For example, suppose the IP address of this computer is 192.168.250.1 and you need to assign IP addresses from 192.168.250.101 to 192.168.250.254, then the configuration would look like this.

subnet 192.168.0.0 netmask 255.255.0.0 { 
        range 192.168.250.101 192.168.250.254; 
        option subnet-mask 255.255.0.0; 
        option broadcast-address 192.168.255.255; 
}

I remind you that these data are fictitious and only show an example of the configuration. You must replace them with the appropriate ones.

Before restarting the service, open this file /etc/default/isc-dhcp-server and add your network interface on INTERFACESV4 section.

:~# nano /etc/default/isc-dhcp-server

NOTE: If you don’t know what your network interface is, you can do it by running the ip or ifconfig command.

So, you can restart the service.

:~# systemctl restart isc-dhcp-server

Assigning a static IP

It is possible to assign a static address to one or more hosts within the network. To do this, create a file in /etc/dhcpd/hosts and place the following.

:~# nano /etc/dhcp/hosts

host nombre_host {
hardware ethernet [MAC];
fixed-addres [IP];
}

I mean, it has to stay that way:

host angelosradar {
        hardware ethernet E1:3E:49:1C:BF:34;
        fixed-address 192.168.250.55;
}

And that’s it.

NOTE: Only one DHCP server must exist in each network segment. If you have a router or ADSL modem, it is most likely that they have the DHCP service. In order for these steps to work for you, you must disconnect from them. Or disable the DHCP service on them.

Conclusion

A DHCP server is a simple thing to do, however, it is good to have knowledge about your network to do it correctly.

The post Set up a DHCP server on Debian 10/ Debian 9? appeared first on Linux Windows and android Tutorials.

Things to check before you start

• Assign Static IP address to the server
• Administrative privilege

Step 1: Install the DHCP Server Role in Windows Server 2019

Note: Remember already I have logged on as a domain administrator on WS2K19-DC01 machine. So we have sufficient permission to install DHCP server role and to authorize the DHCP server in Active Directory environment.

1. First of all open Server Manager Console, as we are going to install the DHCP server role.

2. On Server Manager dashboard, Click on Manage and select Add Roles and Features.

3. On before you begin, Click on Next button on the next screen.

4. On the Select installation type console, make sure you select Role-based or feature-based installation and click Next button.

5. On the Select destination server screen, select our local server WS2K19-DC01 and click on Next.

6. On the Select server roles console, select the DHCP Server role for installation.

7. As soon as you choose DHCP, a new window appears. Click Add Features to add required features to manager DHCP server properly. Click on Next.

8. On the select features console, just click next because we do not require any extra features at the moment.

9. On the DHCP Server console, you can read brief information about DHCP server. When you ready, click next to continue.

10. On the “Confirm installation” selections console, Click on Install to start the installation process.

11. This will take some time to complete.
12. Once installation completes, click on “Complete DHCP configuration” link to start the “DHCP post-install wizard”.

In case, if you close the console still you can start the “DHCP post-install wizard” by clicking on yellow exclamation mark on the flag in server manager dashboard.

Step 2: DHCP Post Install Configuration

1. On description console, you can read what DHCP post-install configuration wizard is going to do. This will create two security groups for DHCP administration:    DHCP Administrators    DHCP Users If the server where you are installing DHCP server role is a domain controller or member server, then this wizard is also going to register DHCP service in Active Directory as well. That is known as a DHCP authorization in Active Directory. Click on Next to continue.

2. On Authorization console, here we need to specify the user credential to register DHCP service in Active Directory. Since we have login as a Domain Administrator and the user has the privilege to do that, I am going with default selection “MYLAB\administrator”. Click on commit to proceed.

3. Once the security group creation and DHCP authorization complete successfully. Click on Close button to close the DHCP post-install configuration wizard.

That’s it, we have successfully completed the installation of DHCP server role on Windows Server 2019 machine. The next task is to create DHCP scopes.

What is DHCP Scope?

A scope is a range of IP addresses on a particular subnet that a DHCP server has selected for allocation to clients when they make a DHCP request. 
You can use DHCP management console or PowerShell to create DHCP scope. In this tutorial we will create IPv4 DHCP scope using DHCP management console. You can also refer my video on YouTube to Install and Configure DHCP on Server 2019.

Step 3: Create IPv4 DHCP Scope

1. On Server Manager console, Click on Tools and select DHCP to open DHCP management tool.

2. On the DHCP console, expand your server name. In my case it is ws2k19-dc01.mylab.local.

3. Select IPv4. On right pane you can see brief overview about DHCP scope and how to create it.

4. Right click on IPv4 and select “New Scope” option.

5. The New Scope wizard starts. Click on Next.

6. On the Scope Name screen, type any name of your choice to scope name. Add a description for scope, so you can identify the scope information. Then click Next button.

7. On the IP Address Range screen, provide an IP address range (Start IP address and End IP address). For this demo I am using 172.18.72.100 to 172.18.72.254 with subnet mask 255.255.255.0.  Once you did with all, click next to proceed.

8. On the “Add Exclusions” and Delay screen, leave it empty. Click on Next.

9. On the Lease Duration screen, I will change the default lease duration and set new lease duration to 8 hours. You can adjust it as per your requirement. Click on Next to continue.

10. On Configure DHCP Option, we can configure additional DHCP options such as Gateways IP address, DNS server address etc. Select “Yes, I want to configure these options now” and click on Next to continue.

11. On Router (Default Gateway) page, add your gateways IP address and click Next. (Don’t forget to click on add button after specifying gateways address)

12. We have installed the DHCP server role on our Domain Controller, so the wizard will automatically detect the DNS server’s address. If you wish to add another DNS server address you can but for this demo will use our local DNS address only. Click Next.

13. If you have any WINS server on your network, you can specify the address here. I am going to click on next button as we don’t have any WINS server.

14. On the “Activate Scope” screen, select “Yes, I want to activate this scope now”. Your DHCP server is not able assign IP address to client request, Until you activate the scope. Click Next.

15. On the next screen, click Finish to create a DHCP scope and close the wizard.

16. On the DHCP Console, Now you can see your newly created scope ready to distribute IP addresses to client computers.

After this we can safely say that our DHCP server is configured and ready to allocate TCP/IP settings to the DHCP clients.

The post Install and configure DHCP in Windows Server 2019 Step By Step appeared first on Linux Windows and android Tutorials.