Debian 12 Bookworm: Install DHCP Sarver and Client

Introduction

Debian 12 "Bookworm" is the latest stable release of the Debian operating system, known for its robustness, security, and extensive software repositories. As an open-source Linux distribution, it caters to a wide range of users from servers to Client

Overview Configure DHCP Server Configure DHCP Client

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• Configure DHCP Client

Overview

What

A DHCP (Dynamic Host Configuration Protocol) server automatically assigns IP addresses and other network configuration parameters to devices on a network, enabling them to communicate with other IP networks.

Who

This guide is intended for network administrators and IT professionals who need to set up and manage a DHCP server on Debian 12 (Bookworm).

Where

The DHCP server is set up on a machine running Debian 12 (Bookworm), which will serve IP addresses to devices within a specific network.

When

This setup is performed during the initial configuration of a network or when migrating an existing network to a new DHCP server running Debian 12 (Bookworm).

Why

Setting up a DHCP server is essential for network management as it simplifies the administration of IP addresses and ensures devices can automatically obtain the necessary network configurations.

Pros	Cons
Automatically assigns IP addresses, reducing manual configuration effort.	Single point of failure if the DHCP server goes down, potentially impacting the entire network.
Centralized management of IP address assignments and configurations.	Requires proper configuration and monitoring to avoid IP address conflicts.
Supports dynamic IP address allocation, making it easier to manage devices that frequently join or leave the network.	Potential security risks if unauthorized devices connect to the network and obtain IP addresses.
Improves network efficiency by ensuring devices always have the correct IP settings.	Additional network traffic as devices communicate with the DHCP server to obtain or renew IP addresses.

How

To set up a DHCP server on Debian 12 (Bookworm), follow these steps:

Install the ISC DHCP server package	using the command: (e.g., `sudo apt install isc-dhcp-server`)
Edit the DHCP server configuration	file located at (e.g., `/etc/dhcp/dhcpd.conf`) to define the network and IP address range.
Start and Enable DHCP Service	Start the DHCP server service and enable it to start on boot (e.g., `sudo systemctl start isc-dhcp-server` and `sudo systemctl enable isc-dhcp-server`).
Verify the DHCP server is running	assigning IP addresses correctly by checking the DHCP leases file at (e.g., `/var/lib/dhcp/dhcpd.leases`)

Consequences

Setting up a DHCP server can have both positive and negative consequences:

Positive	Simplifies network management. Reduces the risk of IP address conflicts. Facilitates device connectivity. Ensures consistent network settings.
Negative	If misconfigured, can disrupt network operations. Can be a target for network attacks. Requires regular maintenance. Dependency on server availability.

Conclusion

DHCP is an essential service for managing IP addresses in a network efficiently. While it offers many benefits in terms of automation and consistency, it also requires proper configuration and security measures to avoid potential issues. Implementing a DHCP server on Debian 12 Bookworm can greatly streamline network management, but it's important to be aware of the potential drawbacks and address them proactively.

Configure DHCP Server

Configure DHCP ( Dynamic Host Configuration Protocol ) Server to assign IP addresses to client hosts in local network.

Step [1]Install and Configure DHCP. On this example, it shows only for IPv4 configuration.

        
root@bizantum:~# apt -y install isc-dhcp-server
root@bizantum:~# vi /etc/default/isc-dhcp-server
# line 4 : uncomment
DHCPDv4_CONF=/etc/dhcp/dhcpd.conf
# line 17 : specify interface to listen (replace it to your environment)
INTERFACESv4="enp1s0"
root@bizantum:~# vi /etc/dhcp/dhcpd.conf
# line 7 : specify domain name
option domain-name "srv.world";
# line 8 : specify nameserver's hostname or IP address
option domain-name-servers bizantum.srv.world;
# line 21 : uncomment (this DHCP server to be declared valid)
authoritative;
# add to the end
# specify network address and subnetmask
subnet 10.0.0.0 netmask 255.255.255.0 {
    # specify gateway
    option routers 10.0.0.1;
    # specify subnet mask
    option subnet-mask 255.255.255.0;
    # specify the range of lease IP address
    range dynamic-bootp 10.0.0.200 10.0.0.254;
}

root@bizantum:~# systemctl restart isc-dhcp-server
        
        

Step [2]It's possible to see leased IP address in the file below from DHCP Server to DHCP Clients.

        
root@bizantum:~# ll /var/lib/dhcp

drwxrwxr-x  2 root  dhcpd 4096 Apr 26 07:42 ./
drwxr-xr-x 40 root  root  4096 Apr 26 07:16 ../
-rw-r--r--  1 dhcpd dhcpd  580 Apr 26 07:48 dhcpd.leases
-rw-rw-r--  1 root  dhcpd  219 Apr 26 07:36 dhcpd.leases~
-rw-r--r--  1 dhcpd dhcpd  219 Apr 26 07:36 dhcpd6.leases
-rw-rw-r--  1 root  dhcpd    0 Apr 26 07:36 dhcpd6.leases~

root@bizantum:~# cat /var/lib/dhcp/dhcpd.leases
# The format of this file is documented in the dhcpd.leases(5) manual page.
# This lease file was written by isc-dhcp-4.4.1

# authoring-byte-order entry is generated, DO NOT DELETE
authoring-byte-order little-endian;

server-duid "\000\001\000\001)\372^\331RT\000\253\225,";

lease 10.0.0.200 {
  starts 2 2022/04/26 07:48:59;
  ends 2 2022/04/26 07:58:59;
  cltt 2 2022/04/26 07:48:59;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 52:54:00:87:24:2c;
  uid "\377VPM\230\000\002\000\000\253\021\022\004\021\002*n\225\336";
}
.....
.....
        
        

Configure DHCP Client

Configure DHCP Client to get IP address from DHCP Server in local network.

On Debian 12

Step [1]For Debian Clients, Configure like follows.

        
root@bizantum:~# vi /etc/network/interfaces
# change to [dhcp] on target interface line
iface enp1s0 inet dhcp
root@bizantum:~# systemctl restart ifup@enp1s0
        
        

On Windows

Configure DHCP Client on Windows computer. This example is based on Windows 11.

Step [2]Right-click the start button and open the [Network connection], and then click the [Ethernet].

Step [3] That's OK if [IP assignment] is [DHCP]. If not, click the [Edit] button.

Step [4]If clicked [Edit] button on previous section, following window is shown. Select [Automatic (DHCP)] and save.

Step [5]Confirm the Network connection status, that's OK if IP is assigned.