DHCP-4.4.3-P1

Config Files

/etc/dhcp/dhclient.conf and /etc/dhcp/dhcpd.conf

Client Configuration

Create a basic /etc/dhcp/dhclient.conf by running the following command as the root user:

install -vdm755 /etc/dhcp &&
cat > /etc/dhcp/dhclient.conf << "EOF"
# Begin /etc/dhcp/dhclient.conf
#
# Basic dhclient.conf(5)

#prepend domain-name-servers 127.0.0.1;
request subnet-mask, broadcast-address, time-offset, routers,
        domain-name, domain-name-servers, domain-search, host-name,
        netbios-name-servers, netbios-scope, interface-mtu,
        ntp-servers;
require subnet-mask, domain-name-servers;
#timeout 60;
#retry 60;
#reboot 10;
#select-timeout 5;
#initial-interval 2;

# End /etc/dhcp/dhclient.conf
EOF

See man 5 dhclient.conf for additional options.

Now create the /var/lib/dhclient directory which will contain DHCP Client leases by running the following command as the root user:

install -v -dm 755 /var/lib/dhclient

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

dhclient <eth0>

Replace <eth0> with your desired interface. If you want more verbose output, add the -v parameter to the command above.

If you want to configure network interfaces at boot using dhclient, you need to install the /lib/services/dhclient script included in blfs-bootscripts-20230101 package:

make install-service-dhclient

Next, create the /etc/sysconfig/ifconfig.eth0 configuration file with the following commands as the root user:

cat > /etc/sysconfig/ifconfig.eth0 << "EOF"
ONBOOT="yes"
IFACE="eth0"
SERVICE="dhclient"
DHCP_START=""
DHCP_STOP=""

# Set PRINTIP="yes" to have the script print
# the DHCP assigned IP address
PRINTIP="no"

# Set PRINTALL="yes" to print the DHCP assigned values for
# IP, SM, DG, and 1st NS. This requires PRINTIP="yes".
PRINTALL="no"
EOF

Adjust the file to suit your needs.

For more information on the appropriate DHCP_START and DHCP_STOP values see man 8 dhclient.

Server Configuration

Note that you only need the DHCP server if you want to issue LAN addresses over your network. The DHCP client doesn't need the server in order to function properly.

Start with creating /etc/dhcp/dhcpd.conf by running the following command as the root user:

cat > /etc/dhcp/dhcpd.conf << "EOF"
# Begin /etc/dhcp/dhcpd.conf
#
# Example dhcpd.conf(5)

# Use this to enable / disable dynamic dns updates globally.
ddns-update-style none;

# option definitions common to all supported networks...
option domain-name "example.org";
option domain-name-servers ns1.example.org, ns2.example.org;

default-lease-time 600;
max-lease-time 7200;

# This is a very basic subnet declaration.
subnet 10.254.239.0 netmask 255.255.255.224 {
  range 10.254.239.10 10.254.239.20;
  option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
}

# End /etc/dhcp/dhcpd.conf
EOF

Adjust the file to suit your needs. See man 5 dhcpd.conf for additional options.

Now create the /var/lib/dhcpd/dhcpd.leases directory which will contain DHCP Server leases by running the following commands as the root user:

install -v -dm 755 /var/lib/dhcpd &&
touch /var/lib/dhcpd/dhcpd.leases

If you want to start the DHCP Server at boot, install the /etc/rc.d/init.d/dhcpd init script included in the blfs-bootscripts-20230101 package:

make install-dhcpd

You will need to edit the /etc/sysconfig/dhcpd in order to set the interface on which dhcpd will serve the DHCP requests.