Introduction to dhcpcd

dhcpcd is an implementation of the DHCP client specified in RFC2131. A DHCP client is useful for connecting your computer to a network which uses DHCP to assign network addresses. dhcpcd strives to be a fully featured, yet very lightweight DHCP client.



Development versions of BLFS may not build or run some packages properly if dependencies have been updated since the most recent stable versions of the book.

Package Information

dhcpcd Dependencies


LLVM-14.0.6 (with Clang), ntp-4.2.8p15, chronyd, and ypbind

User Notes: https://wiki.linuxfromscratch.org/blfs/wiki/dhcpcd

Installation of dhcpcd

Recent releases of dhcpcd implement privilege separation. Additional installation steps are necessary to set up the proper environment, which are performed by issuing the following commands as the root user:

install  -v -m700 -d /var/lib/dhcpcd &&

groupadd -g 52 dhcpcd        &&
useradd  -c 'dhcpcd PrivSep' \
         -d /var/lib/dhcpcd  \
         -g dhcpcd           \
         -s /bin/false     \
         -u 52 dhcpcd &&
chown    -v dhcpcd:dhcpcd /var/lib/dhcpcd 

Install dhcpcd by running the following commands:

./configure --prefix=/usr                \
            --sysconfdir=/etc            \
            --libexecdir=/usr/lib/dhcpcd \
            --dbdir=/var/lib/dhcpcd      \
            --runstatedir=/run           \
            --privsepuser=dhcpcd         &&

To test the results, issue: make test.

Now, as the root user:

make install

Command Explanations

--libexecdir=/usr/lib/dhcpcd: Set a more proper location for dhcpcd internal libraries.

--dbdir=/var/lib/dhcpcd: The default /var/db is not FHS-compliant

--runstatedir=/run: The default /var/run is a symbolic link to /run.

--with-hook=...: You can optionally install more hooks, for example to install some configuration files such as ntp.conf. The set of hooks is in the dhcpcd-hooks directory in the build tree.

Configuring dhcpcd

Config Files


General Configuration Information

If you want to configure network interfaces at boot using dhcpcd, you need to install the systemd unit included in blfs-systemd-units-20220720 package by running the following command as the root user:

make install-dhcpcd


The default behavior of dhcpcd is to set the hostname and the mtu. It also overwrites /etc/resolv.conf and /etc/ntp.conf. These modifications to system configuration files are done by hooks which are stored in /lib/dhcpcd/dhcpcd-hooks. Setup dhcpcd by removing or adding hooks from/to that directory. The execution of hooks can be disabled by using the --nohook (-C) command line option or by the nohook option in the /etc/dhcpcd.conf file.



Make sure that you disable the systemd-networkd service or configure it not to manage the interfaces you want to manage with dhcpcd.

At this point you can test if dhcpcd is behaving as expected by running the following command as the root user:

systemctl start dhcpcd@eth0

To start dhcpcd on a specific interface at boot, enable the previously installed systemd unit by running the following command as the root user:

systemctl enable dhcpcd@eth0

Replace eth0 with the actual interface name.


Installed Program: dhcpcd
Installed Library: /usr/lib/dhcpcd/dev/udev.so
Installed Directory: /{usr,var}/lib/dhcpcd and /usr/share/dhcpcd

Short Descriptions


is an implementation of the DHCP client specified in RFC2131


adds udev support for interface arrival and departure; this is because udev likes to rename the interface, which it can't do if dhcpcd grabs it first