Installation of ISC Kea DHCP Server
Install ISC Kea DHCP Server by running
the following commands:
./configure --prefix=/usr \
--sysconfdir=/etc \
--localstatedir=/var \
--enable-shell \
--with-openssl \
--disable-static \
--docdir=/usr/share/doc/kea-2.4.0 &&
make
To test the results, issue: make check.
To install the ISC Kea DHCP Server suite,
issue the following commands as the
root user:
make -j1 install
Command Explanations
--with-pgsql or --with-mysql:
ISC Kea can store the leases on a
database. This might be useful in large environments running
a cluster of DHCP servers. Using the memfile
backend (which is a CSV file stored locally) is possible anyhow.
--enable-generate-docs:
If documentation is to be rebuilt, add that option. Several
dependencies must be installed for generating the documentation.
make -j1 install: ISC does not recommend
any form of parallel or job server options when doing the install.
Configuring ISC Kea DHCP Server
The support of IPv4, IPv6 and DDNS has been split into
separate servers which runs independently from each other. Each
of them has its own configuration file. Additional configuration
files come from the keactrl agent which is uses to control the
servers in an easy way.
Consult the
Kea Administrator Reference Manual
for detailed information about the configuration of ISC Kea
as it is a quite capable system. The configuration shown a bare
minimum to get a DHCP server running but it already includes
configuration for DDNS (Dynamic DNS). That setup might be working
for small networks with a few clients and low traffic. For greater
installations with thousands of clients, ISC Kea
can be configured to use databases (mariadb or postgresql) to store
the leases and build a cluster with multiple nodes. It can
be integrated to ISC Stork
which is a management dashboard to ISC Kea.
If you want to start the DHCP Server at boot, install the
kea-dhcpd.service
unit included in the
blfs-systemd-units-20230816
package:
make install-kea-dhcpd
Config Files
/etc/kea/keactrl.conf,
/etc/kea/kea-ctrl-agent.conf,
/etc/kea/kea-dhcp4.conf,
/etc/kea/kea-dhcp6.conf and
/etc/kea/kea-dhcp-ddns.conf
Kea Control Configuration
keactrl is used to control the
independent servers (IPv4, IPv6, DDNS). Its configuration file
/etc/kea/keactrl.conf is installed by
default and includes many path settings which are defined
due to the configure at build time. It also
includes settings to specify which of the servers should be
started.
Control Agent
The Control Agent is a daemon which allows the
(re)configuration of the Kea DHCP service via REST API.
Set ctrl_agent=yes to start the
control agent (service providing a REST API), set
ctrl_agent=no in case the control agent
is not needed.
IPv4 DHCP server
This daemon handles requests for IPv4 addresses.
Set dhcp4=yes to start it, set
dhcp4=no in case DHCP service for IPv4
is not wanted.
IPv6 DHCP server
This daemon handles requests for IPv6 addresses.
Set dhcp6=yes to start it, set
dhcp6=no in case DHCP service for IPv6
is not wanted.
Dynamic DNS
This daemon is used to update a DNS server dynamically
when Kea assigns an IP address to a device.
Set dhcp_ddns=yes to enable it, set
dhcp_ddns=no in case dynamic DNS updates
are not wanted.
The Netconf service is not installed because required
dependencies are not covered by the current BLFS book.
With the following command, Kea will be configured to
start the dhcp service for IPv4 and the
dynamic DNS update, while the control agent and
the dhcp service for IPv6 remains down. Tweak the command to
match your needs on started services and execute as the
root user:
sed -e "s/^dhcp4=.*/dhcp4=yes/" \
-e "s/^dhcp6=.*/dhcp6=no/" \
-e "s/^dhcp_ddns=.*/dhcp_ddns=yes/" \
-e "s/^ctrl_agent=.*/ctrl_agent=no/" \
-i /etc/kea/keactrl.conf
Control Agent Configuration
The provided configuration could be used without changes
but in BLFS objects like sockets are stored in
/run
rather than in
/tmp.
cat > /etc/kea/kea-ctrl-agent.conf << "EOF"
// Begin /etc/kea/kea-ctrl-agent.conf
{
// This is a basic configuration for the Kea Control Agent.
// RESTful interface to be available at http://127.0.0.1:8000/
"Control-agent": {
"http-host": "127.0.0.1",
"http-port": 8000,
"control-sockets": {
"dhcp4": {
"socket-type": "unix",
"socket-name": "/run/kea4-ctrl-socket"
},
"dhcp6": {
"socket-type": "unix",
"socket-name": "/run/kea6-ctrl-socket"
},
"d2": {
"socket-type": "unix",
"socket-name": "/run/kea-ddns-ctrl-socket"
}
},
"loggers": [
{
"name": "kea-ctrl-agent",
"output_options": [
{
"output": "/var/log/kea-ctrl-agent.log"
"pattern": "%D{%Y-%m-%d %H:%M:%S.%q} %-5p %m\n"
}
],
"severity": "INFO",
"debuglevel": 0
}
]
}
}
// End /etc/kea/kea-ctrl-agent.conf
EOF
IPv4 DHCP Server Configuration
A sample configuration file is created in /etc/kea/kea-dhcp4.conf.
Adjust the file to suit your needs or overwrite it by using
the following sample as the root
user:
cat > /etc/kea/kea-dhcp4.conf << "EOF"
// Begin /etc/kea/kea-dhcp4.conf
{
"Dhcp4": {
// Add names of your network interfaces to listen on.
"interfaces-config": {
"interfaces": [ "eth0", "eth2" ]
},
"control-socket": {
"socket-type": "unix",
"socket-name": "/run/kea4-ctrl-socket"
},
"lease-database": {
"type": "memfile",
"lfc-interval": 3600
},
"expired-leases-processing": {
"reclaim-timer-wait-time": 10,
"flush-reclaimed-timer-wait-time": 25,
"hold-reclaimed-time": 3600,
"max-reclaim-leases": 100,
"max-reclaim-time": 250,
"unwarned-reclaim-cycles": 5
},
"renew-timer": 900,
"rebind-timer": 1800,
"valid-lifetime": 3600,
// Enable DDNS - Kea will dynamically update the DNS
"ddns-send-updates" : true,
"ddns-qualifying-suffix": "your.domain.tld",
"dhcp-ddns" : {
"enable-updates": true
},
"subnet4": [
{
"subnet": "192.168.56.0/24",
"pools": [ { "pool": "192.168.56.16 - 192.168.56.254" } ],
"option-data": [
{
"name": "domain-name",
"data": "your.domain.tld"
},
{
"name": "domain-name-servers",
"data": "192.168.56.2, 192.168.3.7"
},
{
"name": "domain-search",
"data": "your.domain.tld"
},
{
"name": "routers",
"data": "192.168.56.2"
}
]
}
],
"loggers": [
{
"name": "kea-dhcp4",
"output_options": [
{
"output": "/var/log/kea-dhcp4.log",
"pattern": "%D{%Y-%m-%d %H:%M:%S.%q} %-5p %m\n"
}
],
"severity": "INFO",
"debuglevel": 0
}
]
}
}
// End /etc/kea/kea-dhcp4.conf
EOF
The configuration for IPv6 is similar to the configuration
of IPv4. The configuration file is
/etc/kea/kea-dhcp6.conf.
Dynamic DNS Configuration
If there is a BIND-9.18.20 server running,
ISC Kea can update the DNS when
it gives an IP address to a client. A sample configuration
file is created in /etc/kea/kea-dhcp-ddns.conf.
Adjust the file to suit your needs or overwrite it by using
the following sample as the root
user:
cat > /etc/kea/kea-dhcp-ddns.conf << "EOF"
// Begin /etc/kea/kea-dhcp-ddns.conf
{
"DhcpDdns": {
"ip-address": "127.0.0.1",
"port": 53001,
"control-socket": {
"socket-type": "unix",
"socket-name": "/run/kea-ddns-ctrl-socket"
},
"tsig-keys": [
{
"name" : "rndc-key",
"algorithm" : "hmac-sha256",
"secret" : "1FU5hD7faYaajQCjSdA54JkTPQxbbPrRnzOKqHcD9cM="
}
],
"forward-ddns" : {
"ddns-domains" : [
{
"name" : "your.domain.tld.",
"key-name": "rndc-key",
"dns-servers" : [
{
"ip-address" : "127.0.0.1",
"port" : 53
}
]
}
]
},
"reverse-ddns" : {
"ddns-domains" : [
{
"name" : "56.168.192.in-addr.arpa.",
"key-name": "rndc-key",
"dns-servers" : [
{
"ip-address" : "127.0.0.1",
"port" : 53
}
]
}
]
},
"loggers": [
{
"name": "kea-dhcp-ddns",
"output_options": [
{
"output": "/var/log/kea-ddns.log",
"pattern": "%D{%Y-%m-%d %H:%M:%S.%q} %-5p %m\n"
}
],
"severity": "INFO",
"debuglevel": 0
}
]
}
}
// End /etc/kea/kea-dhcp-ddns.conf
EOF
![[Note]](../images/note.png)
Note
The value of secret is just an example.
Generate the key for your installation by using the
rndc-confgen -a command or the
tsig-keygen command which both are
provided by BIND-9.18.20.
In this sample config it is assumed that the DNS server
runs on the same machine as Kea does (accessable via
127.0.0.1) and that this machine has
the IP 192.168.56.2.