[Linux] DHCP

What is DHCP?

---

Setting DHCP

DHCP
Server

apt install -u isc-dhcp-server

vim /etc/dhcp/dhcpd.conf

option domain-name "<Domain Name>";
option domain-name-servers <Name Server IP Address>;

subnet 192.168.0.0 netmask 255.255.255.0 {
	range 192.168.0.2 192.168.0.254;
}

vim /etc/default/isc-dhcp-server
INTERFACESv4="ens33"
INTERFACESv6="ens33"

ifconfig ens33 192.168.0.1

systemctl restart isc-dhcp-server

dhcp-lrease-list

Client

vim /etc/netplan/00-installer-config.yaml

network:
  ethernets:
    ens33:
      dhcp4: true
  version: 2

netplan apply

DHCP Relay
Server

apt install -y isc-dhcp-server
apt install -y isc-dhcp-relay

vim /etc/dhcp/dhcpd.conf

option domain-name-servers <Name Server IP Address>;


subnet 192.168.0.0 netmask 255.255.255.0 {
	range 192.168.0.2 192.168.0.254;
    option routers 192.168.0.1;
    interface ens33;
}

```yaml
vim /etc/default/isc-dhcp-server
INTERFACESv4="eth1"

systemctl restart isc-dhcp-server

vim /etc/default/isc-dhcp-relay
SERVICES="<Network Interface IP Address>"
INTERFACESv4="ens33"

systemctl restart isc-dhcp-relay

Router

vim /etc/default/isc-dhcp-relay
INTERFACES="eth1 eth2"

systemctl restart isc-dhcp-relay

---

Trouble Shooting

아래는 App Armor Error이다.
Can't open /var/lib/dhcp/dhcpd.leases for append

vim /etc/default/grub
GRUB_CMDLINE_LINUX="apparmor=0"

update-grub

reboot

systemctl stop apparmor
sytsemctl disable apparmor