BOOTPD(8) BSD System Manager's Manual 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 man-
ually, 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-initial-
ize.
-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.
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 bool-
ean 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 Computer//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) If this property is set to true, bootpd calls exit() if it detects that another DHCP server is present on
one of the interfaces that DHCP is enabled on. The default value is false.
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 configura-
tion 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 stati-
cally 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 super-
net 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 con-
version 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 com-
mand-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 direc-
tory 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 NBImage-
Info.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 Root-
Path 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 sup-
ported 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 disk-
less 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 "Power-
Book3,1".
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 prop-
erty 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 mistak-
enly 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 dis-
abled.
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 direc-
tories 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 perfor-
mance.
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)
Mac OS X February 8, 2007 Mac OS X