- Allowed Values For Macronutrients
- Mac Value Guide
- Best Value Mac
- Used Mac Value
- See Full List On Journaldev.com
Freddie Mac Requirements for Rural Properties Q&A. Explore the rural housing market and open your business to new opportunities. We'll work with you to better understand our appraisal and underwriting requirements for rural properties so you can help more borrowers in rural communities purchase a home. B = Value is the TACO Class I Soil Component of the Groundwater Ingestion Exposure Route concentration (35 IAC 742.Appendix B, Tables A and B). C = Value is the TACO-defined Acceptable Detection Limit (ADL) for the chemical in soil. D = Value is the lowest TACO Class I concentration between column range 6.25 to 6.64 and column range.
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When you turn on iterative calculations without changing the values for maximum iterations or maximum change, Excel stops calculating after 100 iterations, or after all values in the circular reference change by less than 0.001 between iterations, whichever comes first. Explore the world of Mac. Check out MacBook Pro, iMac Pro, MacBook Air, iMac, and more. Visit the Apple site to learn, buy, and get support. Lock cells to protect them in Excel for Mac. If so, under Allow users of this sheet to, choose the elements that you want people to be able to select or change.
Introduction
Understanding networking is a fundamental part of configuring complex environments on the internet. This has implications when trying to communicate between servers efficiently, developing secure network policies, and keeping your nodes organized.
In a previous guide, we went over some basic networking terminology. You should look through that guide to make sure you are familiar with the concepts presented there.
In this article, we will discuss some more specific concepts that are involved with designing or interacting with networked computers. Specifically, we will be covering network classes, subnets, and CIDR notation for grouping IP addresses.
Understanding IP addresses
Every location or device on a network must be addressable. This is simply a term that means that it can be reached by referencing its designation under a predefined system of addresses. In the normal TCP/IP model of network layering, this is handled on a few different layers, but usually, when we refer to an address on a network, we are talking about an IP address.
IP addresses allow network resources to be reached through a network interface. If one computer wants to communicate with another computer, it can address the information to the remote computer’s IP address. Assuming that the two computers are on the same network, or that the different computers and devices in between can translate requests across networks, the computers should be able to reach each other and send information.
Each IP address must be unique on its own network. Networks can be isolated from one another, and they can be bridged and translated to provide access between distinct networks. A system called Network Address Translation, allows the addresses to be rewritten when packets traverse network borders to allow them to continue on to their correct destination. This allows the same IP address to be used on multiple, isolated networks while still allowing these to communicate with each other if configured correctly.
The difference between IPv4 and IPv6
There are two revisions of the IP protocol that are widely implemented on systems today. IPv4, which is the fourth version of the protocol, currently is what the majority of systems support. The newer, sixth revision, called IPv6, is being rolled out with greater frequency due to improvements in the protocol and the limitations of IPv4 address space. Simply put, the world now has too many internet-connected devices for the amount of addresses available through IPv4.
IPv4 addresses are 32-bit addresses. Each byte, or 8-bit segment of the address, is divided by a period and typically expressed as a number 0-255. Even though these numbers are typically expressed in decimal to aid in human comprehension, each segment is usually referred to as an octet to express the fact that it is a representation of 8 bits.
A typical IPv4 address looks something like this:
The lowest value in each octet is a 0, and the highest value is 255.
We can also express this in binary to get a better idea of how the four octets will look. We will separate each 4 bits by a space for readability and replace the dots with dashes:
Recognizing that these two formats represent the same number will be important for understanding concepts later on.
Although there are some other differences in the protocol and background functionality of IPv4 and IPv6, the most noticeable difference is the address space. IPv6 expresses addresses as an 128-bit number. To put that into perspective, this means that IPv6 has space for more than 7.9×10<sup>28</sup> times the amount of addresses as IPv4.
To express this extended address range, IPv6 is generally written out as eight segments of four hexadecimal digits. Hexadecimal numbers represent the numbers 0-15 by using the digits 0-9, as well as the numbers a-f to express the higher values. A typical IPv6 address might look something like this:
You may also see these addresses written in a compact format. The rules of IPv6 allow you to remove any leading zeros from each octet, and to replace a single range of zeroed groups with a double colon (::).
For instance, if you have one group in an IPv6 address that looks like this:
You could instead just type:
To demonstrate the second case, if you have a range in an IPv6 address with multiple groups as zeroes, like this:
You could compact this like so (also removing the leading zeros of the group like we did above):
You can do this only once per address, or else the full address will be unable to be reconstructed.
While IPv6 is becoming more common every day, in this guide, we will be exploring the remaining concepts using IPv4 addresses because it is easier to discuss with a smaller address space.
IPv4 Addresses Classes and Reserved Ranges
IP addresses are typically made of two separate components. The first part of the address is used to identify the network that the address is a part of. The part that comes afterwards is used to specify a specific host within that network.
Where the network specification ends and the host specification begins depends on how the network is configured. We will discuss this more thoroughly momentarily.
IPv4 addresses were traditionally divided into five different “classes”, named A through E, meant to differentiate segments of the available addressable IPv4 space. These are defined by the first four bits of each address. You can identify what class an IP address belongs to by looking at these bits.
Here is a translation table that defines the addresses based on their leading bits:
- Class A
- 0-- : If the first bit of an IPv4 address is “0”, this means that the address is part of class A. This means that any address from 0.0.0.0 to 127.255.255.255 is in class A.
- Class B
- 10– : Class B includes any address from 128.0.0.0 to 191.255.255.255. This represents the addresses that have a “1” for their first bit, but don’t have a “1” for their second bit.
- Class C
- 110- : Class C is defined as the addresses ranging from 192.0.0.0 to 223.255.255.255. This represents all of the addresses with a “1” for their first two bits, but without a “1” for their third bit.
- Class D
- 1110 : This class includes addresses that have “111” as their first three bits, but a “0” for the next bit. This address range includes addresses from 224.0.0.0 to 239.255.255.255.
- Class E
- 1111 : This class defines addresses between 240.0.0.0 and 255.255.255.255. Any address that begins with four “1” bits is included in this class.
Class D addresses are reserved for multi-casting protocols, which allow a packet to be sent to a group of hosts in one movement. Class E addresses are reserved for future and experimental use, and are largely not used.
Traditionally, each of the regular classes (A-C) divided the networking and host portions of the address differently to accommodate different sized networks. Class A addresses used the remainder of the first octet to represent the network and the rest of the address to define hosts. This was good for defining a few networks with a lot of hosts each.
The class B addresses used the first two octets (the remainder of the first, and the entire second) to define the network and the rest to define the hosts on each network. The class C addresses used the first three octets to define the network and the last octet to define hosts within that network.
The division of large portions of IP space into classes is now almost a legacy concept. Originally, this was implemented as a stop-gap for the problem of rapidly depleting IPv4 addresses (you can have multiple computers with the same host if they are in separate networks). This was replaced largely by later schemes that we will discuss below.
Reserved Private Ranges
There are also some portions of the IPv4 space that are reserved for specific uses.
One of the most useful reserved ranges is the loopback range specified by addresses from 127.0.0.0 to 127.255.255.255. This range is used by each host to test networking to itself. Typically, this is expressed by the first address in this range: 127.0.0.1.
Each of the normal classes also have a range within them that is used to designate private network addresses. For instance, for class A addresses, the addresses from 10.0.0.0 to 10.255.255.255 are reserved for private network assignment. For class B, this range is 172.16.0.0 to 172.31.255.255. For class C, the range of 192.168.0.0 to 192.168.255.255 is reserved for private usage.
Any computer that is not hooked up to the internet directly (any computer that goes through a router or other NAT system) can use these addresses at will.
There are additional address ranges reserved for specific use-cases. You can find a summary of reserved addresses here.
Netmasks and Subnets
The process of dividing a network into smaller network sections is called subnetting. This can be useful for many different purposes and helps isolate groups of hosts together and deal with them easily.
As we discussed above, each address space is divided into a network portion and a host portion. The amount the address that each of these take up is dependent on the class that the address belongs to. For instance, for class C addresses, the first 3 octets are used to describe the network. For the address
192.168.0.15
, the 192.168.0
portion describes the network and the 15
describes the host.By default, each network has only one subnet, which contains all of the host addresses defined within. A netmask is basically a specification of the amount of address bits that are used for the network portion. A subnet mask is another netmask within used to further divide the network.
Each bit of the address that is considered significant for describing the network should be represented as a “1” in the netmask.
For instance, the address we discussed above,
192.168.0.15
can be expressed like this, in binary:As we described above, the network portion for class C addresses is the first 3 octets, or the first 24 bits. Since these are the significant bits that we want to preserve, the netmask would be:
This can be written in the normal IPv4 format as
255.255.255.0
. Any bit that is a “0” in the binary representation of the netmask is considered part of the host portion of the address and can be variable. The bits that are “1” are static, however, for the network or subnetwork that is being discussed.We determine the network portion of the address by applying a bitwise AND operation to between the address and the netmask. A bitwise AND operation will basically save the networking portion of the address and discard the host portion. The result of this on our above example that represents our network is:
This can be expressed as
192.168.0.0
. The host specification is then the difference between these original value and the host portion. In our case, the host is “0000 1111
” or 15
.The idea of subnetting is to take a portion of the host space of an address, and use it as an additional networking specification to divide the address space again.
For instance, a netmask of
255.255.255.0
as we saw above leaves us with 254 hosts in the network (you cannot end in 0 or 255 because these are reserved). If we wanted to divide this into two subnetworks, we could use one bit of the conventional host portion of the address as the subnet mask.So, continuing with our example, the networking portion is:
The host portion is:
We can use the first bit of our host to designate a subnetwork. We can do this by adjusting the subnet mask from this:
To this:
In traditional IPv4 notation, this would be expressed as
192.168.0.128
. What we have done here is to designate the first bit of the last octet as significant in addressing the network. This effectively produces two subnetworks. The first subnetwork is from 192.168.0.1
to 192.168.0.127
. The second subnetwork contains the hosts 192.168.0.129
to 192.168.0.255
. Traditionally, the subnet itself must not be used as an address.If we use more bits out of the host space for networking, we can get more and more subnetworks.
CIDR Notation
A system called Classless Inter-Domain Routing, or CIDR, was developed as an alternative to traditional subnetting. The idea is that you can add a specification in the IP address itself as to the number of significant bits that make up the routing or networking portion.
For example, we could express the idea that the IP address
192.168.0.15
is associated with the netmask 255.255.255.0
by using the CIDR notation of 192.168.0.15/24
. This means that the first 24 bits of the IP address given are considered significant for the network routing.This allows us some interesting possibilities. We can use these to reference “supernets”. In this case, we mean a more inclusive address range that is not possible with a traditional subnet mask. For instance, in a class C network, like above, we could not combine the addresses from the networks
192.168.0.0
and 192.168.1.0
because the netmask for class C addresses is 255.255.255.0
.However, using CIDR notation, we can combine these blocks by referencing this chunk as
192.168.0.0/23
. This specifies that there are 23 bits used for the network portion that we are referring to.So the first network (192.168.0.0) could be represented like this in binary:
While the second network (192.168.1.0) would be like this:
The CIDR address we specified indicates that the first 23 bits are used for the network block we are referencing. This is equivalent to a netmask of
255.255.254.0
, or:As you can see, with this block the 24th bit can be either 0 or 1 and it will still match, because the network block only cares about the first 23 digits.
Basically, CIDR allows us more control over addressing continuous blocks of IP addresses. This is much more useful than the subnetting we talked about originally.
Conclusion
Hopefully by now, you should have a working understanding of some of the networking implications of the IP protocol. While dealing with this type of networking is not always intuitive, and may be difficult to work with at times, it is important to understand what is going on in order to configure your software and components correctly.
There are various calculators and tools online that will help you understand some of these concepts and get the correct addresses and ranges that you need by typing in certain information. Here, you can find a subnet calculator, a CIDR range finder, and an IP address to binary octets converter. Use these tools to help you when making networking decisions.
![Allowed Values For Mac Allowed Values For Mac](https://www.researchgate.net/profile/M_Evdokimova/publication/226760175/figure/tbl1/AS:669275035553833@1536579011839/Allowable-values-of-the-ecological-state-of-soils-for-the-lands-of-different-economic.png)
<div class=“author”>By Justin Ellingwood</div>
Note: This chapter describes property list keys specific to the macOS implementation of App Sandbox. They are not available in iOS.
In your macOS Xcode project, configure fine-grained security permissions by enabling settings in the Summary tab of the target editor. These settings, in turn, add Boolean values to entitlement keys in the target’s
.entitlements
property list file. The values are then incorporated into the target’s code signature when you build the project.You can think of using App Sandbox entitlements as a two-step process:
- Sandbox a target, which removes most capabilities for interacting with the system
- Restore capabilities to the sandboxed target, as needed, by configuring App Sandbox entitlements
At runtime, if a target requires a capability or a system resource for which the target isn’t entitled, the sandbox daemon (
sandboxd
) logs a violation message to the console.For more information about App Sandbox, read App Sandbox Design Guide.
App Sandbox Entitlement Keys
This section describes the keys you can use to confer capabilities to a sandboxed app in macOS. The first key enables App Sandbox; the others configure the sandbox. If App Sandbox is not enabled, the other keys in this section are meaningless.
The value to use for any of these keys is a Boolean
YES
or NO
, with the default value in each case being NO
. If you are editing the .entitlements
file directly in a text editor, the corresponding Boolean values to use are <true/>
and <false/>
. The default value for each key is false, so you can (and generally should) leave out the entitlement entirely rather than specifying a false value.In cases where there are read-only and read/write entitlement key pairs, use of either key in the pair is mutually exclusive with the other.
Add these keys by using the Summary tab of the Xcode target editor. You can also add them directly to a target’s
.entitlements
file with the Xcode property list editor.For information on additional entitlements for handling special circumstances, see App Sandbox Temporary Exception Entitlements.
For each key in this table, providing a Boolean value of
YES
enables the corresponding capability (unless otherwise noted).Capability
Enables App Sandbox for a target in an Xcode project
Allows access to group containers that are shared among multiple apps produced by a single development team, and allows certain additional interprocess communication between the apps
Supported in macOS v10.7.5 and in v10.8.3 and later. The format for this attribute is described in Adding an App to an App Group.
Read-only access to the user’s Movies folder and iTunes movies
For details, see Enabling Access to Files in Standard Locations.
Read/write access to the user’s Movies folder and iTunes movies
For details, see Enabling Access to Files in Standard Locations.
Read-only access to the user’s Music folder
For details, see Enabling Access to Files in Standard Locations.
Read/write access to the user’s Music folder
For details, see Enabling Access to Files in Standard Locations.
Read-only access to the user’s Pictures folder
For details, see Enabling Access to Files in Standard Locations.
Read/write access to the user’s Pictures folder
For details, see Enabling Access to Files in Standard Locations.
Communication with AVB devices
For details, see Enabling Hardware Access.
Interaction with Bluetooth devices
For details, see Enabling Hardware Access.
Capture of movies and still images using the built-in camera, if available
For details, see Enabling Hardware Access.
Interaction with FireWire devices (currently, does not support interaction with audio/video devices such as DV cameras)
For details, see Enabling Hardware Access.
Recording of audio using the built-in microphone, if available, along with access to audio input using any Core Audio API that supports audio input
For details, see Enabling Hardware Access.
Interaction with serial devices
For details, see Enabling Hardware Access.
Interaction with USB devices, including HID devices such as joysticks
For details, see Enabling Hardware Access.
Read/write access to the user’s Downloads folder
For details, see Enabling Access to Files in Standard Locations.
Use of app-scoped bookmarks and URLs
For details, see Enabling Security-Scoped Bookmark and URL Access.
Use of document-scoped bookmarks and URLs
For details, see Enabling Security-Scoped Bookmark and URL Access.
Read-only access to files the user has selected using an Open or Save dialog
For details, see Enabling User-Selected File Access.
Read/write access to files the user has selected using an Open or Save dialog
For details, see Enabling User-Selected File Access.
Allows apps to write executable files.
For details, see Enabling User-Selected File Access.
Child process inheritance of the parent’s sandbox
For details, see Enabling App Sandbox Inheritance.
Network socket for connecting to other machines
For details, see Enabling Network Access.
Network socket for listening for incoming connections initiated by other machines
For details, see Enabling Network Access.
com.apple.security.personal-information.addressbook
Read/write access to contacts in the user’s address book; allows apps to infer the default address book if more than one is present on a system
For details, see Enabling Personal Information Access.
Read/write access to the user’s calendars
For details, see Enabling Personal Information Access.
Use of the Core Location framework for determining the computer’s geographical location
For details, see Enabling Personal Information Access.
![Allowed Values For Mac Allowed Values For Mac](https://www.researchgate.net/profile/Selim_Kaya/publication/334945351/figure/tbl3/AS:891432051154947@1589545371146/Lifetime-cancer-risk-assessment-for-age-classes_Q320.jpg)
Printing
For details, see Enabling Hardware Access.
Ability to use specific AppleScript scripting access groups within a specific scriptable app
For details, see Enabling Scripting of Other Apps.
Enabling App Sandbox
You enable App Sandbox individually for each target in an macOS Xcode project. For example, you may design a project as a main app, and some helpers in the form of XPC services. You then enable and configure the sandbox for each target individually.
To learn how to enable App Sandbox for your macOS app, which includes performing code signing, see App Sandbox Quick Start in App Sandbox Design Guide. The essential step is to ensure that the target editor checkbox named in Table 4-1 is selected.
Setting | Entitlement key |
---|---|
Enable App Sandboxing | com.apple.security.app-sandbox |
Enabling User-Selected File Access
Xcode provides a pop-up menu, in the Summary tab of the target editor, with choices to enable read-only or read/write access to files and folders that the user explicitly selects. When you enable user-selected file access, you gain programmatic access to files and folders that the user opens using an
NSOpenPanel
object, and files the user saves using an NSSavePanel
object.Certain other user interactions, such as dragging items to your app or choosing items from the Open Recent menu, automatically expand your sandbox to include those items. Similarly, when macOS resumes an app after a reboot, the sandbox is automatically expanded to include any items that are automatically opened.
To enable user-selected file access in your app, use the Xcode target editor setting shown in Table 4-2.
Note: If your app needs to create executable files that are typically executed in some way other than through Launch Services (shell scripts, for example), you should also specify the
com.apple.security.files.user-selected.executable
entitlement.By default, when writing executable files in sandboxed apps, the files are quarantined. Gatekeeper prevents quarantined executable files and other similar files (shell scripts, web archives, and so on) from opening or executing unless the user explicitly launches them from Finder.
If those executables are tools that are intended to run from the command line, such as shell scripts, this presents a problem. With this flag, the file quarantine system allows the app to write non-quarantined executables so that Gatekeeper does not prevent them from executing.
This entitlement does not have an Xcode checkbox, and thus must be added to your app’s entitlement property list manually. For details, see App Sandbox Entitlement Keys.
Setting | Entitlement keys |
---|---|
User Selected File | com.apple.security.files.user-selected.read-only com.apple.security.files.user-selected.read-write |
Enabling Access to Files in Standard Locations
In addition to granting user-selected file access, you can employ entitlements to grant programmatic file access to the following user folders:
- Downloads
- Music
- Movies
- Pictures
The Xcode control for enabling Downloads folder access is a checkbox; the controls for enabling access to these other folders are pop-up menus.
When you enable programmatic access to the user’s Movies folder, you also gain access to their iTunes movies.
Reopening of files by macOS using Resume does not require the presence of any entitlement key.
To enable programmatic access to specific folders, use the Xcode target editor settings shown in Table 4-3.
Setting | Entitlement keys |
---|---|
Downloads Folder | com.apple.security.files.downloads.read-write |
Music Folder | com.apple.security.assets.music.read-only com.apple.security.assets.music.read-write |
Movies Folder | com.apple.security.assets.movies.read-only com.apple.security.assets.movies.read-write |
Pictures Folder | com.apple.security.assets.pictures.read-only com.apple.security.assets.pictures.read-write |
Enabling Security-Scoped Bookmark and URL Access
If you want to provide your sandboxed app with persistent access to file system resources, you must enable security-scoped bookmark and URL access. Security-scoped bookmarks are available starting in macOS v10.7.3.
To add the
bookmarks.app-scope
or bookmarks.document-scope
entitlement, edit the target’s.entitlements
property list file using the Xcode property list editor. Use the entitlement keys shown in Table 4-4, depending on which type of access you want. Use a value of <true/>
for each entitlement you want to enable. You can enable either or both entitlements.For more information on security-scoped bookmarks, read Security-Scoped Bookmarks and Persistent Resource Access in App Sandbox Design Guide.
Allowed Values For Macronutrients
Entitlement key | Description |
---|---|
com.apple.security.files.bookmarks.app-scope | Enables use of app-scoped bookmarks and URLs |
com.apple.security.files.bookmarks.document-scope | Enables use of document-scoped bookmarks and URLs. Version note: in macOS v10.7.3, this entitlement key was named com.apple.security.files.bookmarks.collection-scope |
Enabling Network Access
Xcode’s Network checkboxes in the Summary tab of the target editor let you enable network access for your app.
To enable your app to connect to a server process running on another machine (or on the same machine), enable outgoing network connections.
To enable opening a network listening socket so that other computers can connect to your app, allow incoming network connections.
Note: Both outgoing and incoming connections can send and receive data. The sole difference is in whether your app is initiating the connection or is receiving connections initiated by other apps or other hosts.
To enable network access, use the Xcode target editor settings shown in Table 4-5.
Setting | Entitlement key |
---|---|
Allow Incoming Connections | com.apple.security.network.server |
Allow Outgoing Connections | com.apple.security.network.client |
Enabling Hardware Access
To allow a sandboxed target to access hardware services on a system—USB, printing, or the built-in camera and microphone—enable the corresponding setting in the Summary tab of the Xcode target editor.
- Camera access enables access to video and still image capture using the built-in camera, if available.
- Microphone access enables access to audio recording using the built-in microphone, if available.
- USB access enables the ability to interact with USB devices using USB device access APIs. On violation,
sandboxd
names the I/O Kit class your code tried to access. - Printing access is required if you want to provide a target with the ability to print.
To enable access to hardware, use the Xcode target editor settings shown in Table 4-6.
Setting | Entitlement key |
---|---|
Allow Camera Access | com.apple.security.device.camera |
Allow Microphone Access | com.apple.security.device.audio-input |
Allow USB Access | com.apple.security.device.usb |
Allow Printing | com.apple.security.print |
To allow access to hardware devices for which no checkbox exists in Xcode’s user interface, you must manually add the appropriate entitlement to your app’s entitlements property list. These additional entitlements are listed in Table 4-7. All of these keys take a Boolean value.
Entitlement key | Description |
---|---|
com.apple.security.device.audio-video-bridging | Interaction with AVB devices by using the Audio Video Bridging framework |
com.apple.security.device.bluetooth | Interaction with Bluetooth devices |
com.apple.security.device.firewire | Interaction with FireWire devices (currently, does not support interaction with audio/video devices such as DV cameras) |
com.apple.security.device.serial | Interaction with serial devices |
Enabling Personal Information Access
A user’s personal information is inaccessible to your sandboxed app unless you grant access using the appropriate settings.
- Address Book access enables read/write access to contacts in the user’s address book.
- Location Services access enables use of the Core Location framework to determine the computer’s geographic position.
- Calendar access enables read/write access to the user’s calendars.
To enable access to personal information, use the Xcode target editor settings shown in Table 4-8.
Setting | Entitlement key |
---|---|
Allow Address Book Data Access | com.apple.security.personal-information.addressbook |
Allow Location Services Access | com.apple.security.personal-information.location |
Allow Calendar Data Access | com.apple.security.personal-information.calendars |
Mac Value Guide
Adding an App to an App Group
The
com.apple.security.application-groups
(available in macOS v10.7.5 and v10.8.3 and later) allows multiple apps produced by a single development team to share access to a special group container. This container is intended for content that is not user-facing, such as shared caches or databases.In addition, this attribute allows the apps within the group to share Mach and POSIX semaphores and to use certain other IPC mechanisms among the group’s members. For additional details and naming conventions, read “Mach IPC and POSIX Semaphores and Shared Memory” in App Sandbox Design Guide.
The value for this key must be of type
array
, and must contain one or more string
values, each of which must consist of your development team ID, followed by a period, followed by an arbitrary name chosen by your development team. For example:The group containers are automatically created or added into each app’s sandbox container as determined by the existence of these keys. The group containers are stored in
~/Library/Group Containers/<application-group-id>
, where <application-group-id>
is one of the strings from the array. Your app can obtain the path to the group containers by calling the containerURLForSecurityApplicationGroupIdentifier:
method of NSFileManager
.Best Value Mac
Enabling App Sandbox Inheritance
If your app employs a child process created with either the
posix_spawn
function or the NSTask
class, you can configure the child process to inherit the sandbox of its parent. However, using a child process does not provide the security afforded by using an XPC service.Important: XPC (as described in External Tools, XPC Services, and Privilege Separation) complements App Sandbox and is the preferred technology for implementing privilege separation in an macOS app. Before using a child process, consider using an XPC service instead.
To enable sandbox inheritance, a child target must use exactly two App Sandbox entitlement keys:
com.apple.security.app-sandbox
and com.apple.security.inherit
. If you specify any other App Sandbox entitlement, the system aborts the child process. You can, however, confer other capabilities to a child process by way of iCloud and notification entitlements.The main app in an Xcode project must never have a
YES
value for the inherit
entitlement.To add the
inherit
entitlement, edit the target’s .entitlements
property list file using the Xcode property list editor. Use the entitlement key shown in Table 4-9 with a value of <true/>
.Note: This property causes the child process to inherit only the static rights defined in the main app’s entitlements file, not any rights added to your sandbox after launch (such as PowerBox access to files).
If you need to provide access to files opened after launch, you must either pass the data to the helper or pass a bookmark to the child process. The bookmark need not be a security-scoped bookmark, but it can be, if desired.
If you are using other APIs to create child processes (such as
NSWorkspace
) and wish to have a shared container directory, you must use an app group.Entitlement key | Description |
---|---|
com.apple.security.inherit | Enables App Sandbox inheritance |
Enabling Scripting of Other Apps
If your app needs to control another scriptable app, your app can use the scripting targets entitlement to request access to one or more of the scriptable app’s scripting access groups.
Note: Before you can use this entitlement, the scriptable app must provide scripting access groups. If it does not, you can still control the app, but you use a temporary exception entitlement instead. In some cases, you may use both
scripting-targets
entitlement and a temporary entitlement together, to provide support across different versions of the OS. For more information, see Apple Event Temporary Exception. Entitlement key | Description |
---|---|
com.apple.security.scripting-targets | Ability to use specific AppleScript scripting access groups within a specific scriptable app |
The scripting target entitlement contains a dictionary where each entry has the target app’s code signing identifier as the key, and an array of scripting access groups as the value. Scripting access groups are identified by strings and are specific to an app. For example, the following entry would grant access to composing mail messages with Apple’s Mail app:
Used Mac Value
For more information about how to add scripting access groups to an app, watch WWDC 2012: Secure Automation Techniques in OS X and read the manual page for
sdef
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