DHCP daemon on Raspberry Pi
DHCP stands for “Dynamic Host Configuration Protocol”. The DHCP daemon is the process which assigns IP addresses to computers when they join a network, and gives them other important information about the network.
Here is how to set up and configure dhcpd on Raspbian Stretch:
- Install: Install the package:
sudo apt-get install isc-dhcp-server
When you install this package it is configured to run automatically at boot time. - Configure: There are two files to edit:
-
- Move the existing file /etc/dhcp/dhcpd.conf out of the way so you can replace it with your own:
sudo mv /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.ORIG
(You should keep it because it contains good documentation and examples).
Then create and edit a new file /etc/dhcp/dhcpd.conf containing:1# # Configuration file for DHCP server on Rasberry Pi # ddns-update-style none; option domain-name "wifipi.local"; option domain-name-servers 8.8.8.8; default-lease-time 3600; max-lease-time 86400; authoritative; log-facility local7; # Configure service for local network 192.168.47.0 (the wireless AP) subnet 192.168.47.0 netmask 255.255.255.0 { range 192.168.47.50 192.168.47.250; option routers 192.168.47.1; } ## - Also edit the file /etc/default/isc-dhcp-server to add the line:
INTERFACESv4="wlan0"
Change the name of the interface if you are using something else. (My setup actually runs dhcpd on wlan1.)
- Move the existing file /etc/dhcp/dhcpd.conf out of the way so you can replace it with your own:
-
- Restart: The service should already be enabled, and is probably already running. Restart it with
sudo systemctl restart isc-dhcp-server
The service should already be configured to start automatically. If it does not, use the `systemctl` command to enable the service.
References
- “How to: Make a Raspberry Pi Powered Wifi Repeater” by Dryfire117, https://pastebin.com/A4jUp2Nq ↩
I did all the instructions you mentioned, but it prints this error in terminal when I execute
“sudo systemctl restart isc-dhcp-server”
the error is the following.
job for isc-dhcp-server.service failed because the control process exited with error code.
Yep this configuration is giving error.
Looking over this page again I see a potential problem, in that I run the DHCP daemon on wlan1 (my pi has two wifi interfaces). If you only have one wifi interface then you should change to “wlan0” . I’ve changed these instructions to use wlan0 and added a comment about using a different interface.
Also, even if there is a problem with the restart, the service might still start up after a reboot. It should be configured automatically to start up at boot time.
do you know if this dhcp server supports multiple subnets and multiple listening interfaces?
I’m afraid I do not know if this particular dhcp server supports those.
My dhcp server doesn’t start again after reboot. Tried everything. Someone please help.
There are two “d”s in dns in the example. This will keep it from starting for anyone that copies the example. This got it working for me.
Fixed. Thank you for catching that!
According to this (https://manpages.debian.org/testing/isc-dhcp-server/dhcpd.conf.5.en.html), ddns-update-style is the correct syntax. This gave me an error when running.
Thanks for catching that!
(ddns-update-style was incorrectly written as dns-update-style).
I’ve made the correction.
Hi,
I’ve installed this on a RPi 3B running the latest version of Buster. The DHCP service is running as I can see in leases file:
lease 192.168.1.145 {
starts 6 2020/06/06 11:54:41;
ends 6 2020/06/06 12:04:41;
tstp 6 2020/06/06 12:04:41;
cltt 6 2020/06/06 11:54:41;
binding state free;
hardware ethernet f8:2f:a8:48:e5:3a;
uid “\001\370/\250H\345:”;
set vendor-class-identifier = “PS Vita\000”;
}
However, when I run:
sudo systemctl status isc-dhcp-server.service
I get:
* isc-dhcp-server.service – LSB: DHCP server
Loaded: loaded (/etc/init.d/isc-dhcp-server; generated)
Active: failed (Result: exit-code) since Sat 2020-06-06 13:18:59 CEST; 58min ago
Docs: man:systemd-sysv-generator(8)
Jun 06 13:18:59 rpi-dhcp systemd[1]: Starting LSB: DHCP server…
Jun 06 13:18:59 rpi-dhcp isc-dhcp-server[2694]: Launching IPv4 server only.
Jun 06 13:18:59 rpi-dhcp isc-dhcp-server[2694]: Starting ISC DHCPv4 server: dhcpddhcpd service already running (pid f
Jun 06 13:18:59 rpi-dhcp systemd[1]: isc-dhcp-server.service: Control process exited, code=exited, status=1/FAILURE
Jun 06 13:18:59 rpi-dhcp systemd[1]: isc-dhcp-server.service: Failed with result ‘exit-code’.
Jun 06 13:18:59 rpi-dhcp systemd[1]: Failed to start LSB: DHCP server.
lines 1-11/11 (END)
Can anybody help me understand what’s happening?
Thanks in advance!
Looks like you already had it running and it tried to start it again:
Starting ISC DHCPv4 server: dhcpddhcpd service already running (pid f
It’s the second instance that is terminating, since the service is already running. You can check active services to ensure the DHCP service is running:
systemctl –type=service
If so you just need to figure out why something is trying to start it second time.
Funny enough, the Raspberry Pi documentation does it a different way. See:
https://www.raspberrypi.org/documentation/configuration/wireless/access-point-routed.md
And I will be interested to hear if you get it working. I couldn’t but I think I know my reason now from Erics previous article about setting up an AP.
I was following the instruction to set up ISC DHCP server, but the service failed to start.
However following the Raspbery Pi documentation on setting up a wireless access point, hostapd, working well.
I have a suspicions that the isc dhcp server fails to start because dhcpd service is already running by default.
Thank you for the report. Can you confirm that another dhcpd service is running, and which one? I had to add this to my setup because there was nothing else doing that job.