RPI intranet DHCP Server

RPI-intranet-DHCP-Server.txt

raspbian:DHCP on a inTRAnet

3-apr-2020

$ cat /etc/os-release
...
VERSION="10 (buster)"
...


Used http://www.noveldevices.co.uk/rp-dhcp-server
as my starting point.

step1: Download any package updates and then write the changes to the local package cache
    $ sudo apt-get update

Step 2: Install software
    $ sudo apt-get install isc-dhcp-server
...
[FAIL] Starting ISC DHCP server: dhcpd[....] check syslog for diagnostics. ... failed!
invoke-rc.d: initscript isc-dhcp-server, action "start" failed.

Step 3: The DHCP server requires a static IP address and, by default, the Pi will have a DHCP one
    Note1:  /etc/network/interfaces refers you to /etc/dhcpcd.conf
    Note2: The IP addr of this RPI is 192.168.0.40

    At the bottom of the file
    $ sudo vi /etc/dhcpcd.conf
interface eth0
static ip_address=192.168.0.40/24
static routers=192.168.0.40
static domain_name_servers=192.168.0.40


Step 4: Edit the DHCP configuration file
    Note3: Choose the range of addresses in your sub-net

    At the bottom of the file
    $ sudo vi /etc/dhcp/dhcpd.conf
subnet 192.168.0.0 netmask 255.255.255.0 {
   range 192.168.0.239 192.168.0.240;
   option routers 192.168.0.40;
}

Step 5: Set up the DHCP "defaults" file

    Make the bottom of the file look like this
    $ sudo vi /etc/default/isc-dhcp-server
#INTERFACESv4=""
#INTERFACESv6=""
DHCPDv4_CONF=/etc/dhcp/dhcpd.conf
DHCPDv4_PID=/var/run/dhcpd.pid
INTERFACESv4="eth0"


Step 6: Restart the DHCP daemon process using the service command:

    $ sudo service isc-dhcp-server restart

USEFUL INFORMATION
The DHCP server keeps its current set of leases in a text file in /var/lib/dhcp/dhcpd.leases.

Online documentation for the DHCP server can be viewed on the Pi using man dhcpd.