homeall/dhcphelper
DHCP relay for DHCP Server in the docker container.
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homeall/dhcphelper repository overview
DHCP Relay in docker
Table of Contents
About The Project
You can check the repo on GitHub.
This is a small docker image with a DHCP Helper useful in case when you have a DHCP server in the docker environment and you need a relay for broadcast.
The DHCP server in the container does get only unicast the DHCPOFFER messages when it will have to get broadcast DHCPOFFER messages on the network.
It will not work the DHCP server in docker even in networking host mode unless you are using any DHCP relay.
If you need to know more about how it works DHCP protocol, I highly recommend this link.
Getting Started
It will work on any Linux box amd64 or Raspberry Pi with arm64 or arm32.
Prerequisites
You will need to have:
- Docker
- docker-compose
This step is optional.
Usage
You only need to pass as variable the IP address of DHCP server: "-e IP=X.X.X.X"
You can run as:
docker run --privileged -d --name dhcp --net host -e "IP=172.31.0.100" homeall/dhcphelper:latest
Potentials issues
Please make sure your host has port 67 on UDP open on iptables/firewall of your OS and it is running on network host mode ONLY.
You can run the following command to see that is working::
$ nc -uzvw3 127.0.0.1 67
Connection to 127.0.0.1 port 67 [udp/bootps] succeeded!
On the status column of the docker, you will notice the healthy word. This is telling you that docker is running healtcheck itself in order to make sure it is working properly. Please test yourself using the following command:
$ docker inspect --format "{{json .State.Health }}" dhcp | jq
{
"Status": "healthy",
"FailingStreak": 0,
"Log": [
{
"Start": "2021-01-04T10:28:11.8070681Z",
"End": "2021-01-04T10:28:14.8695872Z",
"ExitCode": 0,
"Output": "127.0.0.1 (127.0.0.1:67) open\n"
}
]
}
Testing
You can run a command from Linux/Mac:
$ sudo nmap --script broadcast-dhcp-discover -e $Your_Interface
Output result:
Starting Nmap 7.91 ( https://nmap.org ) at 2021-01-01 19:40 GMT
Pre-scan script results:
| broadcast-dhcp-discover:
| Response 1 of 1:
| Interface: en0
| IP Offered: 192.168.1.30
| DHCP Message Type: DHCPOFFER
| Server Identifier: 172.31.0.100
| IP Address Lease Time: 2m00s
| Renewal Time Value: 1m00s
| Rebinding Time Value: 1m45s
| Subnet Mask: 255.255.255.0
| Broadcast Address: 192.168.1.255
| Domain Name Server: 172.31.0.100
| Domain Name: lan
| Router: 192.168.1.1
Nmap done: 0 IP addresses (0 hosts up) scanned in 10.26 seconds
PiHole and DHCP Relay
It will work amazing both together dhcphelper and PiHole
A simple docker-compose.yml:
version: "3.3"
services:
pihole:
container_name: pihole
image: pihole/pihole:latest
hostname: pihole
ports:
- "53:53/tcp"
- "53:53/udp"
- "80:80/tcp"
environment:
TZ: 'Europe/London'
WEBPASSWORD: 'admin'
DNS1: '127.0.0.53'
DNS2: 'no'
volumes:
- './etc-pihole/:/etc/pihole/'
depends_on:
- dhcphelper
cap_add:
- NET_ADMIN
restart: unless-stopped
networks:
backend:
ipv4_address: '172.31.0.100'
proxy-tier: {}
dhcphelper:
restart: unless-stopped
container_name: dhcphelper
network_mode: "host"
image: homeall/dhcphelper:latest
environment:
TZ: 'Europe/London'
IP: '172.31.0.100'
cap_add:
- NET_ADMIN
License
Distributed under the MIT license. See LICENSE for more information.
Contact
Please free to open a ticket on Github.
Acknowledgements
- @DerFetzer
- @Simon Kelley who is the author of dnsmasq and dhcp-helper.
Tag summary
Content type
Image
Digest
sha256:ce7ef8e1f…
Size
17.8 kB
Last updated
10 days ago
docker pull homeall/dhcphelper:sha256-2fef746b367354e1faf7c257a3496153b3aa3506ba02404e7019811b33322dce.sig