DHCP : Configure DHCP Server2023/06/15

	Configure DHCP ( Dynamic Host Configuration Protocol ) Server to assign IP addresses to client hosts in local network.
[1]	Install and Configure DHCP. On this example, it shows only for IPv4 configuration.

root@dlp:~#

apt -y install isc-dhcp-server

root@dlp:~#

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@dlp:~#

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

dlp.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@dlp:~#

systemctl restart isc-dhcp-server

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

root@dlp:~#

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@dlp:~#

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";
}
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