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.
![[Note]](../images/note.png)
Development versions of BLFS may not build or run some packages properly if LFS or dependencies have been updated since the most recent stable versions of the books.
Download (HTTP): https://github.com/NetworkConfiguration/dhcpcd/releases/download/v10.1.0/dhcpcd-10.1.0.tar.xz
Download MD5 sum: 1f8e7903d432193f9ecca55a3d978e39
Download size: 268 KB
Estimated disk space required: 3.1 MB (with tests)
Estimated build time: less than 0.1 SBU (with tests)
LLVM-19.1.0 (with Clang), ntp-4.2.8p18, chronyd, and ypbind
Recent releases of dhcpcd optionally support privilege separation. As the practical security benefits of this are unclear for a program like dhcpcd and the setup is more complicated, the book currently defaults to disable it.
If you however would like to use privilege separation, additional
installation steps are necessary to set up the proper environment.
Issue 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
Build dhcpcd without privilege separation by running the following command:
./configure --prefix=/usr \
--sysconfdir=/etc \
--libexecdir=/usr/lib/dhcpcd \
--dbdir=/var/lib/dhcpcd \
--runstatedir=/run \
--disable-privsep &&
make
Alternatively, build dhcpcd with privilege separation by running the following commands:
./configure --prefix=/usr \
--sysconfdir=/etc \
--libexecdir=/usr/lib/dhcpcd \
--dbdir=/var/lib/dhcpcd \
--runstatedir=/run \
--privsepuser=dhcpcd &&
make
To test the results, issue: make test.
Now, as the root user:
make install
--libexecdir=/usr/lib/dhcpcd: This
switch sets a better location for the dhcpcd internal libraries.
--dbdir=/var/lib/dhcpcd:
This switch adjusts the database directory because the default
directory, /var/db, is not
FHS-compliant.
--runstatedir=/run: This
switch sets the runtime state directory because the default
/var/run is a symbolic link to
/run, and using /var/run is deprecated.
--disable-privsep: This
switch disables privilege separation, which is the default in
dhcpcd. This switch is not used in the build configuration where
privilege separation is used.
--privsepuser=dhcpcd: This
switch sets the privilege separation user in the build
configuration where privilege escalation is used.
--with-hook=...: You can optionally
install more hooks, for example to install some configuration files
such as ntp.conf. A set of hooks can
be found in the dhcpcd-hooks
directory in the build tree.
If you want to configure network interfaces at boot using
dhcpcd, you need to
install the systemd unit included in blfs-systemd-units-20241211 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
/usr/lib/dhcpcd/dhcpcd-hooks. You
can change this behavior 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.