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# Dhcpd

From ArchWiki

dhcpd is the Internet Systems Consortium DHCP Server. It is useful for instance on a machine acting as a router on a LAN.

## Installation

Install the dhcp package, available in the official repositories.

## Configuration

Assign an static IPv4 address to the interface you want to use (usually `eth0`). The first 3 bytes of this address cannot be exactly the same as those of another interface.

    # ip link set up dev eth0
    # ip addr add 139.96.30.100/24 dev eth0 # arbitrary address

To have your static ip assigned at boot, see Network Configuration#Static IP address.

The default `dhcpd.conf` contains many uncommented examples, so relocate it

    # mv /etc/dhcpd.conf /etc/dhcpd.conf.example

Edit the configuration file to contain:

    /etc/dhcpd.conf

    # Using the google's dns in the example.
    # Change it to 139.96.30.100 if you have a dns server installed
    option domain-name-servers 8.8.8.8;
    option subnet-mask 255.255.255.0;
    option routers 139.96.30.100;
    subnet 139.96.30.0 netmask 255.255.255.0 {
      range 139.96.30.150 139.96.30.250;
    }

Start the dhcpd daemon with `dhcpd4.service` using systemctl. Optionally, enable it to start automatically on boot.

Now, any computer you connect over ethernet will be assigned an IPv4 address (from `139.96.30.150` to `139.96.30.250` in this example).

## Tips and Tricks

### Listening on only one interface

If your computer is already part of one or several networks, it could be a problem if your computer starts giving ip addresses to machines from the other networks.

In order to force the DHCP server to listen only on one of the network interfaces, you need to specify it in the dhcpd command line.

This is done by editing the configuration file:

    /etc/conf.d/dhcp

    # Assuming the device of your lan is eth1
    DHCP4_ARGS="-q eth1"

Another step is to tell the routing table on which interface to listen to for the 255.255.255.255 broadcasts:

    # ip route add 255.255.255.255 dev eth1

Now, the clients on `eth1` will be managed by your DHCP server without having any impact on any client / server on any other ntework interface.

## Notes

You will see configuration files, etc. related to `dhcpcd`. That one is the DHCP client executable and has nothing to do with `dhcpd`.

## See also

- Dhcpcd

Retrieved from "https://wiki.archlinux.org/index.php?title=Dhcpd&oldid=277222"
Category:

- Networking

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