// This is a basic configuration for the Kea DHCPv4 server. Subnet declarations
// are mostly commented out and no interfaces are listed. Therefore, the servers
// will not listen or respond to any queries.
// The basic configuration must be extended to specify interfaces on which
// the servers should listen. There are a number of example options defined.
// These probably don't make any sense in your network. Make sure you at least
// update the following, before running this example in your network:
// - change the network interface names
// - change the subnets to match your actual network
// - change the option values to match your network
//
// This is just a very basic configuration. Kea comes with large suite (over 30)
// of configuration examples and extensive Kea User's Guide. Please refer to
// those materials to get better understanding of what this software is able to
// do. Comments in this configuration file sometimes refer to sections for more
// details. These are section numbers in Kea User's Guide. The version matching
// your software should come with your Kea package, but it is also available
// in ISC's Knowledgebase (https://kea.readthedocs.io; the direct link for
// the stable version is https://kea.readthedocs.io/).
//
// This configuration file contains only DHCPv4 server's configuration.
// If configurations for other Kea services are also included in this file they
// are ignored by the DHCPv4 server.
{

// DHCPv4 configuration starts here. This section will be read by DHCPv4 server
// and will be ignored by other components.
"Dhcp4": {
    // Add names of your network interfaces to listen on.
    "interfaces-config": {
        // See section 8.2.4 for more details. You probably want to add just
        // interface name (e.g. "eth0" or specific IPv4 address on that
        // interface name (e.g. "eth0/192.0.2.1").
        "interfaces": [ ]

        // Kea DHCPv4 server by default listens using raw sockets. This ensures
        // all packets, including those sent by directly connected clients
        // that don't have IPv4 address yet, are received. However, if your
        // traffic is always relayed, it is often better to use regular
        // UDP sockets. If you want to do that, uncomment this line:
        // "dhcp-socket-type": "udp"
    },

    // Kea supports control channel, which is a way to receive management
    // commands while the server is running. This is a Unix domain socket that
    // receives commands formatted in JSON, e.g. config-set (which sets new
    // configuration), config-reload (which tells Kea to reload its
    // configuration from file), statistic-get (to retrieve statistics) and many
    // more. For detailed description, see Sections 8.8, 16 and 15.
    "control-socket": {
        "socket-type": "unix",
        "socket-name": "kea4-ctrl-socket"
    },

    // Use Memfile lease database backend to store leases in a CSV file.
    // Depending on how Kea was compiled, it may also support SQL databases
    // (MySQL and/or PostgreSQL). Those database backends require more
    // parameters, like name, host and possibly user and password.
    // There are dedicated examples for each backend. See Section 7.2.2 "Lease
    // Storage" for details.
    "lease-database": {
        // Memfile is the simplest and easiest backend to use. It's an in-memory
        // C++ database that stores its state in CSV file.
        "type": "memfile",
        "lfc-interval": 3600
    },

    // Kea allows storing host reservations in a database. If your network is
    // small or you have few reservations, it's probably easier to keep them
    // in the configuration file. If your network is large, it's usually better
    // to use database for it. To enable it, uncomment the following:
    // "hosts-database": {
    //     "type": "mysql",
    //     "name": "kea",
    //     "user": "kea",
    //     "password": "kea",
    //     "host": "localhost",
    //     "port": 3306
    // },
    // See Section 7.2.3 "Hosts storage" for details.

    // Setup reclamation of the expired leases and leases affinity.
    // Expired leases will be reclaimed every 10 seconds. Every 25
    // seconds reclaimed leases, which have expired more than 3600
    // seconds ago, will be removed. The limits for leases reclamation
    // are 100 leases or 250 ms for a single cycle. A warning message
    // will be logged if there are still expired leases in the
    // database after 5 consecutive reclamation cycles.
    // If both "flush-reclaimed-timer-wait-time" and "hold-reclaimed-time" are
    // not 0, when the client sends a release message the lease is expired
    // instead of being deleted from the lease storage.
    "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
    },

    // Global timers specified here apply to all subnets, unless there are
    // subnet specific values defined in particular subnets.
    "renew-timer": 900,
    "rebind-timer": 1800,
    "valid-lifetime": 3600,

    // Many additional parameters can be specified here:
    // - option definitions (if you want to define vendor options, your own
    //                       custom options or perhaps handle standard options
    //                       that Kea does not support out of the box yet)
    // - client classes
    // - hooks
    // - ddns information (how the DHCPv4 component can reach a DDNS daemon)
    //
    // Some of them have examples below, but there are other parameters.
    // Consult Kea User's Guide to find out about them.

    // These are global options. They are going to be sent when a client
    // requests them, unless overwritten with values in more specific scopes.
    // The scope hierarchy is:
    // - global (most generic, can be overwritten by class, subnet or host)
    // - class (can be overwritten by subnet or host)
    // - subnet (can be overwritten by host)
    // - host (most specific, overwrites any other scopes)
    //
    // Not all of those options make sense. Please configure only those that
    // are actually useful in your network.
    //
    // For a complete list of options currently supported by Kea, see
    // Section 7.2.8 "Standard DHCPv4 Options". Kea also supports
    // vendor options (see Section 7.2.10) and allows users to define their
    // own custom options (see Section 7.2.9).
    "option-data": [
        // When specifying options, you typically need to specify
        // one of (name or code) and data. The full option specification
        // covers name, code, space, csv-format and data.
        // space defaults to "dhcp4" which is usually correct, unless you
        // use encapsulate options. csv-format defaults to "true", so
        // this is also correct, unless you want to specify the whole
        // option value as long hex string. For example, to specify
        // domain-name-servers you could do this:
        // {
        //     "name": "domain-name-servers",
        //     "code": 6,
        //     "csv-format": "true",
        //     "space": "dhcp4",
        //     "data": "192.0.2.1, 192.0.2.2"
        // }
        // but it's a lot of writing, so it's easier to do this instead:
        {
            "name": "domain-name-servers",
            "data": "192.0.2.1, 192.0.2.2"
        },

        // Typically people prefer to refer to options by their names, so they
        // don't need to remember the code names. However, some people like
        // to use numerical values. For example, option "domain-name" uses
        // option code 15, so you can reference to it either by
        // "name": "domain-name" or "code": 15.
        {
            "code": 15,
            "data": "example.org"
        },

        // Domain search is also a popular option. It tells the client to
        // attempt to resolve names within those specified domains. For
        // example, name "foo" would be attempted to be resolved as
        // foo.mydomain.example.com and if it fails, then as foo.example.com
        {
            "name": "domain-search",
            "data": "mydomain.example.com, example.com"
        },

        // String options that have a comma in their values need to have
        // it escaped (i.e. each comma is preceded by two backslashes).
        // That's because commas are reserved for separating fields in
        // compound options. At the same time, we need to be conformant
        // with JSON spec, that does not allow "\,". Therefore the
        // slightly uncommon double backslashes notation is needed.

        // Legal JSON escapes are \ followed by "\/bfnrt character
        // or \u followed by 4 hexadecimal numbers (currently Kea
        // supports only \u0000 to \u00ff code points).
        // CSV processing translates '\\' into '\' and '\,' into ','
        // only so for instance '\x' is translated into '\x'. But
        // as it works on a JSON string value each of these '\'
        // characters must be doubled on JSON input.
        {
            "name": "boot-file-name",
            "data": "EST5EDT4\\,M3.2.0/02:00\\,M11.1.0/02:00"
        },

        // Options that take integer values can either be specified in
        // dec or hex format. Hex format could be either plain (e.g. abcd)
        // or prefixed with 0x (e.g. 0xabcd).
        {
            "name": "default-ip-ttl",
            "data": "0xf0"
        }

        // Note that Kea provides some of the options on its own. In particular,
        // it sends IP Address lease type (code 51, based on valid-lifetime
        // parameter, Subnet mask (code 1, based on subnet definition), Renewal
        // time (code 58, based on renew-timer parameter), Rebind time (code 59,
        // based on rebind-timer parameter).
    ],

    // Other global parameters that can be defined here are option definitions
    // (this is useful if you want to use vendor options, your own custom
    // options or perhaps handle options that Kea does not handle out of the box
    // yet).

    // You can also define classes. If classes are defined, incoming packets
    // may be assigned to specific classes. A client class can represent any
    // group of devices that share some common characteristic, e.g. Windows
    // devices, iphones, broken printers that require special options, etc.
    // Based on the class information, you can then allow or reject clients
    // to use certain subnets, add special options for them or change values
    // of some fixed fields.
    "client-classes": [
        {
            // This specifies a name of this class. It's useful if you need to
            // reference this class.
            "name": "voip",

            // This is a test. It is an expression that is being evaluated on
            // each incoming packet. It is supposed to evaluate to either
            // true or false. If it's true, the packet is added to specified
            // class. See Section 12 for a list of available expressions. There
            // are several dozens. Section 8.2.14 for more details for DHCPv4
            // classification and Section 9.2.19 for DHCPv6.
            "test": "substring(option[60].hex,0,6) == 'Aastra'",

            // If a client belongs to this class, you can define extra behavior.
            // For example, certain fields in DHCPv4 packet will be set to
            // certain values.
            "next-server": "192.0.2.254",
            "server-hostname": "hal9000",
            "boot-file-name": "/dev/null"

            // You can also define option values here if you want devices from
            // this class to receive special options.
        }
    ],

    // Another thing possible here are hooks. Kea supports a powerful mechanism
    // that allows loading external libraries that can extract information and
    // even influence how the server processes packets. Those libraries include
    // additional forensic logging capabilities, ability to reserve hosts in
    // more flexible ways, and even add extra commands. For a list of available
    // hook libraries, see https://gitlab.isc.org/isc-projects/kea/wikis/Hooks-available.
    // "hooks-libraries": [
    //   {
    //       // Forensic Logging library generates forensic type of audit trail
    //       // of all devices serviced by Kea, including their identifiers
    //       // (like MAC address), their location in the network, times
    //       // when they were active etc.
    //       "library": "/usr/local/lib/kea/hooks/libdhcp_legal_log.so",
    //       "parameters": {
    //           "path": "/var/lib/kea",
    //           "base-name": "kea-forensic4"
    //       }
    //   },
    //   {
    //       // Flexible identifier (flex-id). Kea software provides a way to
    //       // handle host reservations that include addresses, prefixes,
    //       // options, client classes and other features. The reservation can
    //       // be based on hardware address, DUID, circuit-id or client-id in
    //       // DHCPv4 and using hardware address or DUID in DHCPv6. However,
    //       // there are sometimes scenario where the reservation is more
    //       // complex, e.g. uses other options that mentioned above, uses part
    //       // of specific options or perhaps even a combination of several
    //       // options and fields to uniquely identify a client. Those scenarios
    //       // are addressed by the Flexible Identifiers hook application.
    //       "library": "/usr/local/lib/kea/hooks/libdhcp_flex_id.so",
    //       "parameters": {
    //           "identifier-expression": "relay4[2].hex"
    //       }
    //   }
    // ],

    // Below an example of a simple IPv4 subnet declaration. Uncomment to enable
    // it. This is a list, denoted with [ ], of structures, each denoted with
    // { }. Each structure describes a single subnet and may have several
    // parameters. One of those parameters is "pools" that is also a list of
    // structures.
    "subnet4": [
        {
            // This defines the whole subnet. Kea will use this information to
            // determine where the clients are connected. This is the whole
            // subnet in your network.

            // Subnet identifier should be unique for each subnet.
            "id": 1,

            // This is mandatory parameter for each subnet.
            "subnet": "192.0.2.0/24",

            // Pools define the actual part of your subnet that is governed
            // by Kea. Technically this is optional parameter, but it's
            // almost always needed for DHCP to do its job. If you omit it,
            // clients won't be able to get addresses, unless there are
            // host reservations defined for them.
            "pools": [ { "pool": "192.0.2.1 - 192.0.2.200" } ],

            // These are options that are subnet specific. In most cases,
            // you need to define at least routers option, as without this
            // option your clients will not be able to reach their default
            // gateway and will not have Internet connectivity.
            "option-data": [
                {
                    // For each IPv4 subnet you most likely need to specify at
                    // least one router.
                    "name": "routers",
                    "data": "192.0.2.1"
                }
            ],

            // Kea offers host reservations mechanism. Kea supports reservations
            // by several different types of identifiers: hw-address
            // (hardware/MAC address of the client), duid (DUID inserted by the
            // client), client-id (client identifier inserted by the client) and
            // circuit-id (circuit identifier inserted by the relay agent).
            //
            // Kea also support flexible identifier (flex-id), which lets you
            // specify an expression that is evaluated for each incoming packet.
            // Resulting value is then used for as an identifier.
            //
            // Note that reservations are subnet-specific in Kea. This is
            // different than ISC DHCP. Keep that in mind when migrating
            // your configurations.
            "reservations": [

                // This is a reservation for a specific hardware/MAC address.
                // It's a rather simple reservation: just an address and nothing
                // else.
                {
                    "hw-address": "1a:1b:1c:1d:1e:1f",
                    "ip-address": "192.0.2.201"
                },

                // This is a reservation for a specific client-id. It also shows
                // the this client will get a reserved hostname. A hostname can
                // be defined for any identifier type, not just client-id.
                {
                    "client-id": "01:11:22:33:44:55:66",
                    "ip-address": "192.0.2.202",
                    "hostname": "special-snowflake"
                },

                // The third reservation is based on DUID. This reservation defines
                // a special option values for this particular client. If the
                // domain-name-servers option would have been defined on a global,
                // subnet or class level, the host specific values take preference.
                {
                    "duid": "01:02:03:04:05",
                    "ip-address": "192.0.2.203",
                    "option-data": [ {
                        "name": "domain-name-servers",
                        "data": "10.1.1.202, 10.1.1.203"
                    } ]
                },

                // The fourth reservation is based on circuit-id. This is an option
                // inserted by the relay agent that forwards the packet from client
                // to the server.  In this example the host is also assigned vendor
                // specific options.
                //
                // When using reservations, it is useful to configure
                // reservations-global, reservations-in-subnet,
                // reservations-out-of-pool (subnet specific parameters)
                // and host-reservation-identifiers (global parameter).
                {
                    "client-id": "01:12:23:34:45:56:67",
                    "ip-address": "192.0.2.204",
                    "option-data": [
                        {
                            "name": "vivso-suboptions",
                            "data": "4491"
                        },
                        {
                            "name": "tftp-servers",
                            "space": "vendor-4491",
                            "data": "10.1.1.202, 10.1.1.203"
                        }
                    ]
                },
                // This reservation is for a client that needs specific DHCPv4
                // fields to be set. Three supported fields are next-server,
                // server-hostname and boot-file-name
                {
                    "client-id": "01:0a:0b:0c:0d:0e:0f",
                    "ip-address": "192.0.2.205",
                    "next-server": "192.0.2.1",
                    "server-hostname": "hal9000",
                    "boot-file-name": "/dev/null"
                },
                // This reservation is using flexible identifier. Instead of
                // relying on specific field, sysadmin can define an expression
                // similar to what is used for client classification,
                // e.g. substring(relay[0].option[17],0,6). Then, based on the
                // value of that expression for incoming packet, the reservation
                // is matched. Expression can be specified either as hex or
                // plain text using single quotes.
                //
                // Note: flexible identifier requires flex_id hook library to be
                // loaded to work.
                {
                    "flex-id": "'s0mEVaLue'",
                    "ip-address": "192.0.2.206"
                }
                // You can add more reservations here.
            ]
            // You can add more subnets there.
        }
    ],

    // There are many, many more parameters that DHCPv4 server is able to use.
    // They were not added here to not overwhelm people with too much
    // information at once.

    // Logging configuration starts here. Kea uses different loggers to log various
    // activities. For details (e.g. names of loggers), see Chapter 18.
    "loggers": [
    {
        // This section affects kea-dhcp4, which is the base logger for DHCPv4
        // component. It tells DHCPv4 server to write all log messages (on
        // severity INFO or more) to a file.
        "name": "kea-dhcp4",
        "output_options": [
            {
                // Specifies the output file. There are several special values
                // supported:
                // - stdout (prints on standard output)
                // - stderr (prints on standard error)
                // - syslog (logs to syslog)
                // - syslog:name (logs to syslog using specified name)
                // Any other value is considered a name of the file
                "output": "kea-dhcp4.log"

                // Shorter log pattern suitable for use with systemd,
                // avoids redundant information
                // "pattern": "%-5p %m\n",

                // This governs whether the log output is flushed to disk after
                // every write.
                // "flush": false,

                // This specifies the maximum size of the file before it is
                // rotated.
                // "maxsize": 1048576,

                // This specifies the maximum number of rotated files to keep.
                // "maxver": 8
            }
        ],
        // This specifies the severity of log messages to keep. Supported values
        // are: FATAL, ERROR, WARN, INFO, DEBUG
        "severity": "INFO",

        // If DEBUG level is specified, this value is used. 0 is least verbose,
        // 99 is most verbose. Be cautious, Kea can generate lots and lots
        // of logs if told to do so.
        "debuglevel": 0
    }
  ]
}
}
