Lab – DHCPv4 com ISC DHCP Server

✅ Download e Instalação do ISC DHCP Server

sudo apt update
sudo apt install isc-dhcp-server

✅ Atribuição de um IPv4 Fixo para o servidor com Netplan

Edição do arquivo Netplan

sudo nano /etc/netplan/01-dhcp-server-config.yaml

⚠️ Altere as permissões do arquivo de configuração:

sudo chmod 600 /etc/netplan/01-dhcp-server-config.yaml

Isso garante que somente o root possa ler e escrever o arquivo, como o Netplan exige.

Configuração da Rede

network:
  version: 2
  ethernets:
    ens3:
      dhcp4: false
      addresses:
        - 172.16.10.254/24
      routes:
        - to: default
          via: 172.16.10.1
      nameservers:
        addresses:
          - 8.8.8.8
          - 1.1.1.1

⚠️ Mantenha a indentação!

Depois de definida a configuração, aplique-a:

sudo netplan apply

✅ Configuração do DHCP Server

Edite o arquivo dhcpd.conf:

sudo nano /etc/dhcp/dhcpd.conf

E insira a configuração de rede:

# dhcpd.conf

# Nome do domínio e DNSs
option domain-name "rede.local";
option domain-name-servers 8.8.8.8, 1.1.1.1;

# Tempo de concessão de IP
default-lease-time 600;
max-lease-time 7200;

# Sem atualizações dinâmicas de DNS
ddns-update-style none;

# Definição da rede local
subnet 172.16.10.0 netmask 255.255.255.0 {
  range 172.16.10.100 172.16.10.200;
  option routers 172.16.10.1;
  option subnet-mask 255.255.255.0;
  option domain-name-servers 8.8.8.8, 1.1.1.1;
  option domain-name "rede.local";

✅ Definir ens3 como interface do DHCP

Edite o arquivo isc-dhcp-server:

sudo nano /etc/default/isc-dhcp-server

Defina a interface ens3:

INTERFACESv4="ens3"
INTERFACESv6=""

Habilite e (re)inicie o serviço:

sudo systemctl restart isc-dhcp-server
sudo systemctl enable isc-dhcp-server
sudo systemctl status isc-dhcp-server

✅ Testes

👍 Verifique o status do serviço:

sudo systemctl status isc-dhcp-server

Saída:

ubuntu@ubuntu-cloud:~$ sudo systemctl status isc-dhcp-server
● isc-dhcp-server.service - ISC DHCP IPv4 server
     Loaded: loaded (/usr/lib/systemd/system/isc-dhcp-server.service; enabled; >
     Active: active (running) since Sun 2025-07-27 17:24:39 UTC; 38min ago
 Invocation: 3836b915b34a4a89a0db752c38f8efbb
       Docs: man:dhcpd(8)
   Main PID: 659 (dhcpd)
      Tasks: 1 (limit: 1110)
     Memory: 4.5M (peak: 4.7M)
        CPU: 96ms
     CGroup: /system.slice/isc-dhcp-server.service
             └─659 dhcpd -user dhcpd -group dhcpd -f -4 -pf /run/dhcp-server/dh>

Jul 27 18:01:48 ubuntu-cloud dhcpd[659]: DHCPDISCOVER from 00:50:79:66:68:00 vi>
Jul 27 18:01:49 ubuntu-cloud dhcpd[659]: DHCPOFFER on 172.16.10.100 to 00:50:79>
Jul 27 18:01:52 ubuntu-cloud dhcpd[659]: DHCPREQUEST for 172.16.10.100 (172.16.>
Jul 27 18:01:52 ubuntu-cloud dhcpd[659]: DHCPACK on 172.16.10.100 to 00:50:79:6>
Jul 27 18:01:54 ubuntu-cloud dhcpd[659]: DHCPDISCOVER from 00:50:79:66:68:01 vi>
Jul 27 18:01:55 ubuntu-cloud dhcpd[659]: DHCPOFFER on 172.16.10.102 to 00:50:79>
Jul 27 18:01:57 ubuntu-cloud dhcpd[659]: DHCPDISCOVER from 0c:50:e6:6b:00:00 (u>
Jul 27 18:01:58 ubuntu-cloud dhcpd[659]: DHCPOFFER on 172.16.10.103 to 0c:50:e6>
Jul 27 18:01:58 ubuntu-cloud dhcpd[659]: DHCPREQUEST for 172.16.10.102 (172.16.>
Jul 27 18:01:58 ubuntu-cloud dhcpd[659]: DHCPACK on 172.16.10.102 to 00:50:79:6>
ubuntu@ubuntu-cloud:~$

👍 Verifique a atribuição de endereços IPv4:

cat /var/lib/dhcp/dhcpd.leases

Saída:

ubuntu@ubuntu-cloud:~$ 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-4.4.3-P1

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

lease 172.16.10.100 {
  starts 0 2025/07/27 18:06:56;
  ends 0 2025/07/27 18:16:56;
  tstp 0 2025/07/27 18:16:56;
  cltt 0 2025/07/27 18:06:56;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 00:50:79:66:68:00;
  uid "\001\000Pyfh\000";
  client-hostname "PC1";
}
lease 172.16.10.102 {
  starts 0 2025/07/27 18:07:02;
  ends 0 2025/07/27 18:17:02;
  tstp 0 2025/07/27 18:17:02;
  cltt 0 2025/07/27 18:07:02;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 00:50:79:66:68:01;
  uid "\001\000Pyfh\001";
  client-hostname "PC2";
}
server-duid "\000\001\000\0010\031\030h\014P\346k\000\000";

ubuntu@ubuntu-cloud:~$