BOOTPD(8)

NAME
bootpd - DHCP/BOOTP/NetBoot server

SYNOPSIS
bootpd [options]

DESCRIPTION
bootpd implements a DHCP/BOOTP server as defined in RFC951, RFC1542, RFC2131, and RFC2132, as well as a BOOTP/DHCP relay agent. It is also a NetBoot server implementing Apple-proprietary NetBoot 1.0 (BOOTP-based) and NetBoot 2.0 BSDP (Boot Server Discovery Protocol). BSDP works along with regular DHCP, using DHCP-format packets with a special vendor-class identifier and vendor-specific options.

bootpd understands and handles requests that arrive via a DHCP/BOOTP relay agent, allowing the server to be centrally located, and serve many remote subnets.

The server is normally invoked by xinetd(8) when a request arrives, but can also be invoked manually. If it is invoked by xinetd(8), bootpd continues to service requests until it is idle for a period of 5 minutes, after which it exits to conserve system resources. If invoked manually, bootpd continues to run indefinitely.

If bootpd receives a SIGHUP (-1) signal, it will re-read its configuration and client binding files.

When a request from a client arrives, the server logs an entry to /var/log/system.log indicating which client made the request, and logs another entry once a reply is sent. This feature can be turned off using the -q option described below.

bootpd reads its configuration settings from /etc/bootpd.plist. There are also a number of command-line options to change its behavior on the fly. Note in particular that options DmNrS can also be controlled via service-control properties. See Service Controls and Filters below.

OPTIONS

-B  Disable BOOTP service. BOOTP is now disabled by default, so specifying this option has no effect.

-b  Only respond if the client's bootfile exists: for BOOTP clients only.

-D  Enable DHCP service. By default, DHCP service is disabled.

-d  Remain in the foreground and produce extra debugging output to stderr.

-I  Disable re-initialization on IP address changes. By default, changes to the server's configured IP addresses cause it to re-initialize.

-i interface
    Enable service on the specified interface. This flag may appear multiple times to enable multiple interfaces. For example,
        bootpd -i en0 -i en1
    forces bootpd to respond only to requests received on ethernet ports en0 and en1. By default, all interfaces are enabled.

-m  Enable NetBoot 1.0 (BOOTP-based) service.

-N  Enable NetBoot 2.0 (BSDP/DHCP-based) service.

-o hop_count
    For relay agent operation, the maximum hop count, default is 4 hops.

-q  Be quiet as possible. Only report serious errors to

-r server_ip
    Relay packets to the specified server_ip, not exceeding the hop count. This option can be specified multiple times, one for each server to relay to.

-S  Enable BOOTP service.

-v  Be more verbose in messages logged to /var/log/system.log.

CONFIGURING BOOTPD
bootpd reads its configuration from /etc/bootpd.plist, an XML property list. The root of the property list is a dictionary. The property list has three main areas:

Root dictionary
    Service Controls and Filters

Subnets
    Subnet Entries

NetBoot
    NetBoot Server Controls

  Service Controls and Filters
The root dictionary in /etc/bootpd.plist contains properties to control whether bootpd will respond to a particular request, There are MAC address filters, DHCP controls, as well as controls to enable services.

The MAC address filter properties are:

allow
    (Array of String) Enables servicing a list of MAC addresses.

deny
    (Array of String) Disables servicing a list of MAC addresses.

When a packet arrives, bootpd checks whether the client's MAC address is in the deny list. If it is, the packet is dropped. Otherwise, if the client's MAC address is in the allow list, the packet continues to be processed, otherwise it is dropped. If neither the allow nor the deny property is specified, the packet continues to be processed.

Allow/deny filtering can be disabled using the ignore_allow_deny property:

ignore_allow_deny
    (Array of String) Disable allow/deny processing on the specified list of interfaces. When a packet arrives on an interface in this list, processing continues without consulting the allow/deny filters.

The service-control properties are:

bootp_enabled
    Enables BOOTP on the specified list of interfaces.

dhcp_enabled
    Enables DHCP on the specified list of interfaces.

netboot_enabled
    Enables NetBoot 2.0 (BSDP/DHCP-based) NetBoot on the specified list of interfaces.

old_netboot_enabled
    Enables NetBoot 1.0 (BOOTP-based) NetBoot on the specified list of interfaces.

relay_enabled
    Enables the relay agent on the specified list of interfaces. Note that this option also requires the relay_ip_list property to be specified.

For each of the properties dhcp_enabled, bootp_enabled, old_netboot_enabled, netboot_enabled, and relay_enabled, the corresponding service can be enabled or disabled for all interfaces, or enabled for just a specific set of interfaces. To enable or disable globally, use a boolean value true or false respectively. To enable just for a specific set of interfaces, use either a string, for a single interface, or an array of strings, one element for each interface.

For example, to enable DHCP on interfaces en0 and en1, disable BOOTP on all interfaces, enable NetBoot on en1, and enable relay agent on interface en1, /etc/bootpd.plist could contain:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>bootp_enabled</key>
        <false/>
        <key>dhcp_enabled</key>
        <array>
                <string>en0</string>
                <string>en1</string>
        </array>
        <key>netboot_enabled</key>
        <string>en1</string>
        <key>relay_enabled</key>
        <array>
                <string>en1</string>
        </array>
</dict>
</plist>

Some additional properties are:

relay_ip_list
    (Array of String) If relay agent functionality is enabled (see relay_enabled above), this property contains the list of IP addresses to relay the packet to.

detect_other_dhcp_server
    (Boolean, Array of String) Enables detecting another DHCP server either globally (Boolean), or only on the specified list of interfaces (Array of String). When another DHCP server is detected on an interface, DHCP service is disabled on that interface until the next time bootpd receives a SIGHUP, or exits.

reply_threshold_seconds
    (Integer) bootpd won't respond to the request until the bp_secs field is at least reply_theshold_seconds. The default value is 0 (zero).

use_open_directory
    (Boolean) If this property is set to true, bootpd will look for static IP address to ethernet address bindings in Open Directory. The default value is true.

dhcp_ignore_client_identifier
    (Boolean) If this property is set to true, the DHCP server tries to ignore the DHCP client identifier option (code 61) in the client's DHCP packet. Instead, the DHCP server tries to use the hardware address fields (bp_htype, bp_hlen, bp_chaddr) of the DHCP packet to identify the client. The default value of this property is false.

use_server_config_for_dhcp_options
    (Boolean) If this property is set to true, the DHCP server tries to use its own configuration to supply the subnet mask, router, DNS server addresses, DNS domain, and DNS domain search options, if those options are missing from the subnet description. If the property is false, the server only uses the information in the subnet description to supply these DHCP options. The default value of this property is true.

  Subnet Entries
The "Subnets" property in /etc/bootpd.plist contains an array of dictionaries, each dictionary corresponds to a single subnet entry.

A subnet entry describes a range of IP addresses, and associated information, such as the subnet mask, router, DNS servers, and other option data. A subnet entry also indicates whether the range is an address pool from which to allocate vs. simply an informational range in order to fulfill requests for option information. The informational range is used when the client's IP address binding is static, or the client knows its own IP address and simply wants relevant option information.

A subnet entry is required to supply the DHCP service with pool(s) of IP address(es), and to inform the server of subnet-specific options and parameters. A subnet entry can also be used to convey network topology information via the supernet property described below.

Subnet entries may not overlap in the IP ranges the describe, nor specify values that are inconsistent. Specifically, applying the net_mask value to each of the values in the net_range must yield the net_address value.

Errors in configuration are logged to /var/log/system.log. There may be multiple entries for a given subnet, allowing different configuration values to be specified for a given sub-range of IP addresses within the subnet. For example, part of the range might be used for statically bound clients, and another for a dynamic address pool.

Each subnet entry is encoded as a dictionary with the following properties:

name
    (String) A descriptive name for the subnet, e.g. "17.202.40/22".

net_mask
    (String) The network mask, e.g. "255.255.252.0". This property is required.

net_address
    (String) The network address, e.g. "17.202.40.0". This property is required.

net_range
    (Array of String) The network address range stored as two values: the first IP address and the last IP address. For example:
    	<array>
    		<string>17.202.40.2</string>
    		<string>17.202.43.254</string>
    	</array>
    This property is required.

allocate
    (Boolean) Indicates whether the DHCP service should allocate IP addresses from the range specified by net_range. A true value means allocate IP addresses, otherwise, the subnet entry is informational only.

lease_min
    (Integer) The minimum allowable lease time (in seconds). This property is ignored unless allocate specifies true. Default value is 3600 (one hour).

lease_max
    (Integer) The maximum allowable lease time (in seconds). This property is ignored unless allocate specifies true. Default value is 3600 (one hour).

supernet
    (String) This property indicates that the subnet is on the same physical broadcast domain as other subnets with the same supernet value.

The server can also supply clients with the following DHCP option information:

dhcp_router
    The IP address of the default router (DHCP option code 3). If this property is not present, the server will attempt to provide its own default route for this option, if it is applicable.

dhcp_domain_name_server
    The IP address(es) of the DNS server(s) (option code 6). If this property is not present, the server will supply its own DNS server configuration (if available).

dhcp_domain_name
    The default DNS domain name (option code 15). If this property is not present, the server will supply its own default domain name (if available).

dhcp_domain_search
    The domain search list (option code 119). If this property is not present, the server will supply its domain search list (if available).

dhcp_ldap_url
    The default LDAP URL (option code 95).

dhcp_netinfo_server_address
    The NetInfo parent server IP address(es) (option code 112).

dhcp_netinfo_server_tag
    The NetInfo parent domain tag (option code 113).

dhcp_url
    The default URL to present in a web browser (option code 114).

dhcp_time_offset
    The time offset from GMT in seconds (option code 2).

dhcp_network_time_protocol_servers
    The network time protocol (NTP) server IP address(es) (option code 42).

dhcp_nb_over_tcpip_name_server
    The NetBIOS over TCP/IP name server IP address(es) (option code 44).

dhcp_nb_over_tcpip_dgram_dist_server
    The NetBIOS over TCP/IP datagram distribution server IP address(es) (option code 45).

dhcp_nb_over_tcpip_node_type
    The NetBIOS over TCP/IP node type (option code 46).

dhcp_nb_over_tcpip_scope
    The NetBIOS over TCP/IP scope string (option code 47).

dhcp_smtp_server
    The Simple Mail Transport Protocol (SMTP) server IP address(es) (option code 69).

dhcp_pop3_server
    The Post Office Protocol (POP3) server IP address(es) (option code 70).

dhcp_nntp_server
    The Network News Transport Protocol (NNTP) server IP address(es) (option code 71).

dhcp_proxy_auto_discovery_url
    The default Web Proxy Auto Discovery URL (option code 252).

DHCP options may also be specified using the naming convention:
	dhcp_option_option_code
replacing option_code with a numeric value in the range of 1 through 254. For example, to specify option code 128, specify a property named dhcp_option_128.

bootpd has a built-in type conversion table for many more options, mostly those specified in RFC 2132, and will try to convert from whatever type the option appears in the property list to the binary, packet format. For example, if bootpd knows that the type of the option is an IP address or list of IP addresses, it converts from the string form of the IP address to the binary, network byte order numeric value.

If the type of the option is a numeric value, it converts from string, integer, or boolean, to the proper sized, network byte-order numeric value.

Regardless of whether bootpd knows the type of the option or not, you can always specify the DHCP option using the data property list type e.g.:
	<key>dhcp_option_128</key>
	<data>
	AAqV1Tzo
	</data>

  NetBoot Server Controls
The "NetBoot" property in /etc/bootpd.plist is encoded as a dictionary, and may contain a number of properties that alter the NetBoot server's default behavior. The properties are:

afp_uid_start
    (Integer) The starting uid used when creating AFP machine users. The default is uid 100.

afp_users_max
    (Integer) The number of AFP machine users to automaticaly create. The default is 50. Note: the server will never remove a user once it is created, so decreasing this value once the server has read it will have no effect.

age_time_seconds
    (Integer) The number of seconds since the client last netbooted before before the client is considered "aged". A client that has aged becomes available for resource reclamation. The server will only reclaim aged client bindings when it runs out of free resources.

machine_name_format
    (String) This property is used to generate a unique name to each NetBoot client. The default value is "NetBoot%03d" (without the double quotes). The format string must be a printf(3) compatible format string that takes a single integer value as an argument. The server ensures that the string is valid by testing the string before using it. The only conversion specifiers that should be used are diouxX.

shadow_size_meg
    (Integer) The size (in megabytes) to allocate for the client shadow file. The default is 48 (megabytes). See Diskless Resources below.

BOOTP/DHCP STATIC BINDINGS
Static IP address to ethernet address bindings are stored in the /etc/bootptab file and in Open Directory. Bindings specified in the /etc/bootptab file take precedence over those in Open Directory.

See bootptab(5) for more information about the /etc/bootptab file.

For Open Directory, bootpd looks at the /Computers records for the following properties:

ENetAddress
    (String) The ethernet MAC address(es) of the computer. Each address must be of the form xx:xx:xx:xx:xx:xx using only the characters 0123456789abcdef. Leading zeros must be specified.

IPAddress
    (String) The IP address(es) of the computer.

IPAddressAndENetAddress
    (String) Pairs of IP and Ethernet MAC addresses of the computer. Each address pair consists of an single IP and MAC address separated by a slash character, e.g. "192.168.1.1/01:23:45:67:89:ab". This attribute should be provided when multiple addresses are provided because not all directories return attribute values in a guaranteed order.

BootFile
    (String) The bootfile to use for this computer.

DHCP SERVICE

If DHCP service is enabled for a client, the server processes the client's packet. The packet may be a request for an IP address and option information (DHCP Discover, DHCP Request) or for just option information (DHCP Inform). The packet might also tell the server that the address is in use by some other host (DHCP Decline), or that the client is done with the IP address (DHCP Release).

The server uses the DHCP client identifier (option 61) if it is present as the unique client identifier, otherwise it uses the htype/hlen/chaddr fields in the DHCP packet.

  IP Allocation
The DHCP server first tries to find a static binding for the client (see section BOOTP/DHCP STATIC BINDINGS above). If one exists, it uses it. If not, it tries to find an existing dynamic binding from its lease database, stored in /var/db/dhcpd_leases. If one exists and it is applicable to the subnet, the server uses it, otherwise, it tries to allocate an address from one of its address pools. If an address is available, the server uses it, otherwise the packet is discarded.

After a suitable IP address is found for the client, the server attempts to insert as many of the requested DHCP options from the client's request as it can into the reply.

When the server allocates an address dynamically, it automatically excludes addresses that appear in static host entries. For example, if the address range goes from 10.0.0.2 through 10.0.0.10, but there is a static entry that specifies 10.0.0.3, that address is automatically excluded from the pool.

The server tries to give the same address back to a client by remembering the binding even after it has expired. The server removes an expired lease entry only when it runs out of addresses, and needs to reclaim an address in order to fulfill a new request.

When the server receives a DHCP Release packet, it sets the expiration for that lease to now, so that it can immediately reclaim the address if needed.

When the server receives a DHCP Decline packet, it removes the client binding from the IP address, and sets the expiration on the "unbound" lease to 10 minutes from now. That allows the address to return to the address pool again without manual intervention and avoids handing out the same in-use IP address over and over.

NETBOOT SERVICE

The NetBoot server enables a client to perform a network boot, that is, access its operating system image over the network instead of from its local drive.

The sequence of events that occur when a NetBoot client is powered are:

1.  firmware gets IP address and image information (using BOOTP, or BSDP/DHCP)

2.  firmware saves relevant packet(s) in memory to be used by client operating system (see step 4 below)

3.  firmware TFTP's the bootfile image, and begins executing it

3.1.
    (Mac OS X only) secondary loader TFTP's kernel and drivers, and begins executing the kernel

4.  client operating system initializes its network stack and accesses its "root" disk using information in packets saved at step 2, uses AFP, NFS, or HTTP to access the image

Apple NetBoot uses a technique called "shadowing", whereby an otherwise read-only disk image appears to the client as a read/write image by "mapping" writes to the original image file to an auxilliary "shadow" file. Subsequent reads from portions that have been written also come from the "shadow" file. The disk image driver in the client operating system manages the shadow mapping and provides the illusion of a writable disk.

The term diskless NetBoot implies that the client receives all of its necessary booting resources from the network, so that a local disk drive is not required, though may still be present.

The NetBoot server supplies a NetBoot client with the resources and information it needs to boot. Two versions of NetBoot are supported: NetBoot 1.0 (BOOTP-based) and NetBoot 2.0 (BSDP/DHCP-based). Service for these two types of NetBoot are controlled individually using command-line options m and N, or using the service configuration properties old_netboot_enabled and netboot_enabled (described above).

The NetBoot 1.0 server supplies the client with its IP address in addition to its boot resources. The server must be able to find a static binding for the client (see BOOTP/DHCP STATIC BINDINGS above), or the server must have an applicable dynamic pool of IP addresses, just as with DHCP. If the server does not also have DHCP service enabled, the pools are only used for NetBoot 1.0 clients. In this case, the server also acts as a DHCP server but only services those clients for which it has an existing binding.

There can only be one NetBoot 1.0 server per subnet because the protocol uses BOOTP, and BOOTP does not support multiple servers. However, the NetBoot 1.0 server will co-exist with an existing DHCP server, assuming it only serves DHCP.

The NetBoot 2.0 server only supplies the client with boot resources. Unlike NetBoot 1.0, there is no limit on the number of NetBoot servers per subnet.

The NetBoot server stores a list of NetBoot client records in the file /var/db/bsdpd_clients. Each client record contains the client name and number assigned by the server, the boot image ID selected by the client, and the client's last boot time.

  NetBoot Image Location
When the NetBoot server initializes, it looks for NetBoot images at well-known locations in the file system. A "NetBoot image" is a directory that ends in the .nbi extension, and contains a valid set of files (described below). If no images are found, NetBoot is temporarily disabled. If it receives a SIGHUP signal, the server again attempts to initialize itself.

The NetBoot server looks for a symbolic link named:

    Library/NetBoot/.sharepoint

at the root of each local volume. If the symlink is valid, and points to a directory, it assumes that the directory contains NetBoot images and that the contents are accessible via TFTP, AFP, NFS, and HTTP. By convention, the directory is named:

    Library/NetBoot/NetBootSPx

where x is a unique number starting at zero (0).

  NetBoot Image (.nbi)
A NetBoot Image is stored in a directory whose name ends with .nbi, and contains a set of files. The directory must contain an NBImageInfo.plist file, one or more bootfiles, and may contain one or more image files. The NBImageInfo.plist file is encoded as an XML property list, and contains information about the image.

The properties defined in the NBImageInfo.plist file and their meanings are:

Name
    (String) The name of the image that appears in the Startup Disk UI.

BootFile
    (String) The path of the first bootfile, relative to either the .nbi directory (for architecture "ppc" only), or a sub-directory of the .nbi directory. The sub-directory names correspond to the Architectures that the NetBoot Image supports. See also the Architectures property below.

IsEnabled
    (Boolean) A flag to mark the image as enabled or not. An image that is disabled will not be offered as a selection by the NetBoot server. Optional, default value is true.

IsDefault
    (Boolean) A flag to mark the image as a default image. Setting this key to true for more than one image can be useful if the EnabledSystemIdentifiers property is also defined (see below). Optional, default value is false.

IsInstall
    (Boolean) A flag to indicate that the image describes an installation image. Optional, default value is false.

Type
    (String) The expected image contents and the mechanism used to supply images to the client. The defined values are:

    Classic
        After downloading the boot file via TFTP, the client OS accesses its images via AFP. The SharedImage and PrivateImage properties (defined below) specify the images to use.

    NFS After downloading the boot files via TFTP, the client OS accesses its "root" filesystem via NFS. The RootPath property (detailed below) specifies the path.

    HTTP
        After downloading the boot files via TFTP, the client accesses its "root" filesystem via HTTP. The RootPath property (detailed below) specifies the path.

    BootFileOnly
        The client downloads the boot file(s), and does not require any additional boot image information.

Kind
    (Integer) The defined image kind values are:
    0 = Mac OS 9
    1 = Mac OS X
    2 = Mac OS X Server
    3 = Hardware Diagnostics

    The default Kind is determined from the Type:

    Type
        Default Kind
    Classic
        0 - Mac OS 9
    NFS 1 - Mac OS X
    HTTP
        1 - Mac OS X
    BootFileOnly
        none

    The Kind must be specified if the Type is BootFileOnly.

Index
    (Integer) The index of the image. This is a 16-bit value used to differentiate between multiple NetBoot images supplied by a server. There are two value ranges:
    1 .. 4095
        Image is local to this server.
    4096 .. 65535
        Image is global and may appear on multiple servers, used for load-balancing.

    The Index forms the lower 16-bits of the unique 32-bit Image ID. IsInstall and Kind make up the remaining bits (with 8 bits reserved).

RootPath
    (String) If Type is "NFS", this is the path of the "root" disk image relative to the .nbi directory. The NetBoot server assumes that the path up to and including the NetBootSPx directory is exported via NFS. Indirect NFS paths are also supported using the syntax:

        <path> = <host>:<mount_path>[:<image_path>]
        <host> = <IP address> | <host_name>

    For example, in the path:

        myserver:/NetBoot:Images/Jaguar.dmg

    the image is on a server named "myserver" with NFS export "/NetBoot" and the image file appears relative to the mount point as "Images/Jaguar.dmg".

    If Type is "HTTP", this is the path of the "root" disk image relative to the .nbi directory. The NetBoot server assumes that the .nbi directory under NetBootSPx is exported via HTTP using the convention:

        http://<server_ip>/NetBoot/NetBootSPx/<image_dir>.nbi

    Indirect HTTP paths are also supported using the HTTP URL syntax:

        <path> = http://[<user>@]<host>[:<port>]/<image_path>
        <user> = <user_name>:<password>
        <host> = <IP address> | <host_name>

    Examples:

        http://myserver:8080/Images/Jaguar.dmg
        http://joe:secret@someserver/Jaguar/Jaguar.dmg

SharedImage
    (String) If Type is "Classic", this is the path of the read/write system disk image used for Mac OS 9.

PrivateImage
    (String) If Type is "Classic", this is the path of the read-only private disk image used to store additional applications for Mac OS 9. Optional.

SupportsDiskless
    (Boolean) A flag that indicates that the image supports diskless clients, and tells the server to allocate resources. If the Type is "Classic", the value of this property is ignored since the server always allocates resources required for diskless clients. See Diskless Resources below.

EnabledSystemIdentifiers
    (Array of String) The list of system identifiers that are enabled for this image. The system identifier for Apple hardware is the model property from the Open Firmware device-tree. Some example model properties are "PowerMac3,3" and "PowerBook3,1".

    If this property is not specified, or the list is empty, the image is enabled for all clients (the default).

    If the server has no images that apply to the client, it will not respond.

    Due to limitations in the NetBoot 1.0 protocol, there is no way for the NetBoot server to differentiate between older clients such as the original bondi-blue iMac or B&W G3 (Yosemite). To enable an image for all NetBoot 1.0 clients, include the pseudo system identifier "/NetBoot1".

Architectures
    (Array of String) The list of architectures that this image supports. Optional, implicit value is an array with a single value "ppc".

    The NetBoot server uses the following logic in conjunction with the (explicit or implicit) value of the Architectures property and the BootFile property:

    bootfile = plist.BootFile.string
    for i = 0; i < plist.Architectures.array.count; i++
        arch = plist.Architectures.array.value[i].string
        if $arch/$bootfile exists
            use $arch/$bootfile
        else if $arch == "ppc" and $bootfile exists
            use $bootfile
        else
            reject this image

    That is, for each architecture in the Architectures list look for a sub-directory of the .nbi directory named architecture. If the BootFile exists within that directory, continue with the next architecture. Otherwise, if the architecture is "ppc", and the BootFile exists directly within the .nbi directory, continue with the next architecture. Otherwise, reject the image. If all Architectures have a valid BootFile, accept the image.

    This logic allows a single-architecture, "ppc"-only NetBoot Image to work as before. The directory structure ensures that a NetBoot Image that only supports non-"ppc" architectures will be rejected by a NetBoot server that doesn't understand the Architectures property. This is important because older NetBoot servers only serve "ppc" images, and they must not mistakenly serve a non-"ppc" image to a "ppc" client.

EnabledMACAddresses
    (Array of String) The exclusive list of MAC addresses for which this image is enabled. A client whose MAC address is on this list may be offered this image, subject to any other filtering that might be in effect, e.g. the Architectures and EnabledSystemIdentifiers properties. If this property is not specified, image MAC address filtering is subject only to the DisabledMACAddresses property, if specified. If this property is defined but the array is empty, the image is disabled.

DisabledMACAddresses
    (Array of String) The list of MAC addresses for which this image is disabled. A client whose MAC address is on this list will not be offered this image. Defining both this property and the EnabledMACAddresses property at the same time is not generally useful, but this property takes precedence. That is, if a client's MAC address appears in both lists, it is disabled.

  NetBoot Image Example: Mac OS 9

The path to the image directory in this example is:
    /Library/NetBoot/NetBootSP0/Mac OS 9.nbi

This directory contains the following files:
    NBImageInfo.plist
    Mac OS ROM
    NetBoot HD.img
    Applications HD.img

The NBImageInfo.plist contains:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist SYSTEM "file://localhost/System/Library/DTDs/PropertyList.dtd">
<plist version="0.9">
<dict>
        <key>BootFile</key>
        <string>Mac OS ROM</string>
        <key>IsEnabled</key>
        <true/>
        <key>Index</key>
        <integer>4</integer>
        <key>IsInstall</key>
        <false/>
        <key>Name</key>
        <string>Mac OS 9.2</string>
        <key>SharedImage</key>
        <string>NetBoot HD.img</string>
        <key>PrivateImage</key>
        <string>Applications HD.img</string>
        <key>Type</key>
        <string>Classic</string>
</dict>
</plist>

The Type is Classic, which means this is a Mac OS 9 NetBoot image, so the implied Kind value is 0 (Mac OS 9). The BootFile property points to "Mac OS ROM". The system image is "NetBoot HD.img". The read-only applications image is "Applications HD.img". The Name of the image is "Mac OS 9.2". IsEnabled is supplied and set to true, so the image is active. The Index is 4, which means the image is local to this server, and will always appear as a unique choice in the client image selection UI.

  NetBoot Image Example: Mac OS X

The path to this example is:
    /Library/NetBoot/NetBootSP0/Jaguar.nbi

This directory contains:
    NBImageInfo.plist
    booter
    mach.macosx
    mach.macosx.mkext
    Jaguar.dmg

The NBImageInfo.plist contains:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist SYSTEM "file://localhost/System/Library/DTDs/PropertyList.dtd">
<plist version="0.9">
<dict>
        <key>BootFile</key>
        <string>booter</string>
        <key>IsEnabled</key>
        <true/>
        <key>Index</key>
        <integer>4096</integer>
        <key>IsInstall</key>
        <false/>
        <key>Name</key>
        <string>Mac OS X (Jaguar)</string>
        <key>RootPath</key>
        <string>Jaguar.dmg</string>
        <key>Type</key>
        <string>NFS</string>
</dict>
</plist>

The Type is NFS, and no Kind is specified, so the server assumes this is a Mac OS X image with Kind 1. The BootFile property points to "booter". Mac OS X uses three separate bootfiles, so the remaining files which must exist, but are not currently verified to exist by the server, are "mach.macosx" and "mach.macosx.mkext". Those names are non-negotiable, since the booter hard-codes those names. The RootPath property indicates that the image file is "Jaguar.dmg". The Index is 4096, so this is a global image, that may appear on multiple NetBoot servers. If another server serves an image of the same Kind, IsInstall, and Index, this image may appear as a single choice in client image selection UI.

  NetBoot Image Example: Mac OS X with Multiple Architectures

The path to this example is:
    /Library/NetBoot/NetBootSP0/Tiger.nbi

This directory contains:
    NBImageInfo.plist
    booter
    mach.macosx
    mach.macosx.mkext
    i386/
        booter
        mach.macosx
        mach.macosx.mkext
    Tiger.dmg

The NBImageInfo.plist contains:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist SYSTEM "file://localhost/System/Library/DTDs/PropertyList.dtd">
<plist version="0.9">
<dict>
        <key>Architectures</key>
        <array>
                <string>i386</string>
                <string>ppc</string>
        </array>
        <key>BootFile</key>
        <string>booter</string>
        <key>IsInstall</key>
        <true/>
        <key>IsEnabled</key>
        <true/>
        <key>Index</key>
        <integer>5000</integer>
        <key>Name</key>
        <string>Mac OS X (Tiger)</string>
        <key>RootPath</key>
        <string>Tiger.dmg</string>
        <key>Type</key>
        <string>NFS</string>
</dict>
</plist>

This example shows how a NetBoot Image that supports multiple architectures is configured. The bootfiles for "ppc" reside directly within the .nbi directory, whereas the bootfiles for "i386" reside within a sub-directory of the .nbi directory named "i386". This image is a Mac OS X installation image that is served over NFS.

  Diskless Resources

The NetBoot server creates and manages per-client AFP user logins as well as per-client directories to give each client its own protected resources. The AFP users are created on the local system with the attribute _creator set to bsdpd.

When the server initializes, it ensures there are at least afp_users_max users with this property. If there are not, it allocates new user entries to make up the difference.

Along with the per-client AFP login, the server creates per-client directories to store the "shadow" files. The server creates these directories on each local volume that contains a symbolic link named:

    Library/NetBoot/.clients

at the root of the volume. If the symlink is valid, and points to a directory, it assumes that the directory should be used for client files. It also assumes that the directory is a valid AFP sharepoint of the same name. By convention, the directory is named:

    Library/NetBoot/NetBootClientsY

where Y is a unique number starting at zero (0).

The server "round-robins" client files across each such directory to distribute load amongst multiple disk drives to improve overall performance.

When the server responds to the client's NetBoot request, it ensures that the "shadow" file is preallocated to shadow_size_meg megabytes. Setting that property high enough avoids having every client fail if the server runs out of disk space. The only clients that fail if the server runs out of disk space are those that run of of space in their own pre-allocated "shadow" files.

Note: the server allocates shadow files for Mac OS 9 NetBoot clients only on local HFS volumes.

SEE ALSO

bootptab(5), xinetd(8), tftpd(8), exports(5)