Mac users in higher security risk situations may wish to enable an optional firmware password on their machines, which offers an advanced level of protection. In short, a firmware password is a lower level layer of security that is set on the actual Mac logic board firmware, rather than at the software layer like FileVault encryption or the standard login password.
The result of setting an firmware password is that a Mac can not be booted from an external boot volume, single user mode, or target disk mode, and it also prevents resetting of PRAM and the ability to boot into safe mode, without logging in through the firmware password first. This effectively prevents a wide variety of methods that could potentially be used to compromise a Mac, and offers exceptional security for users who require such protection.
Like any other essential password, use something memorable but complex, and do not forget a firmware password after it has been set. A lost firmware password is unrecoverable on most modern Macs without a visit to an Apple Store for service and recovery.
Setting a firmware password is rather simple.
• Start up from macOS recovery mode by holding down Command (⌘)-R immediately after turning on your Mac. Release the keys when you see the Apple logo.
• When the utilities window appears, choose Utilities > Firmware Password Utility from the menu bar. On iMac Pro, choose Startup Security Utility instead.
• Click Turn On Firmware Password.
• Enter a firmware password in the fields provided, then click Set Password.
• Quit the utility, then choose Apple () menu > Restart.
The firmware password will not appear during a regular restart or boot of the Mac, it only becomes mandatory when the Mac is attempted to boot from alternate methods. This may be in situations where a Mac is attempted to boot from an macOS installer drive, an external boot volume, recovery mode, single user mode, verbose mode, target disk mode, resetting the PRAM, or any other alternative booting approach that will summon the rather plain looking firmware password window. There are no password hints or additional details provided, only a simple lock logo and a text entry screen. An incorrectly entered firmware password does nothing and offers no indication of login failure except that the Mac won't boot as anticipated.
Safari for both macOS and iOS have a setting you may never have noticed, since we so often have Internet access. This is an easily overlooked feature that’s actually really cool. Here’s how to save your Safari reading list for offline viewing.
In Safari for macOS, choose Safari > Preferences and then click Advanced. You can then check next to the Reading List label Save Articles for Offline Reading Automatically. If that option isn't checked, you can also view the Reading List in the sidebar, right-click an item, and choose Save Offline.
With iOS Safari, you navigate to Settings > Safari and swipe down to the bottom, and then tap the switch to on for Automatically Save Offline. If you have that option disabled, which it is by default, you’re prompted the first time you choose Add to Reading List from the Sharing sheet whether or not to save items from then for offline reading automatically.
Content caching is a new feature available in macOS High Sierra. Content caching reduces bandwidth usage and speeds up installation on supported devices by storing software updates, apps, and other content on local computer.
Content caching is a great idea, especially if you have an always-on (or often-on) Mac in your home or office. Instead of having to download the same stuff over and over, you only do it once. Then, any other devices on your network pull their data from your Mac, instead of from Apple's servers. That's probably a boon for Apple's data bills, but for us it could make a huge difference to update speeds. When this feature is switched on, both Mac and iOS content is saved locally.
How to set up content caching in macOS High Sierra?
• Open Sharing from System Preferences.
• Unlock the pane. Click the padlock icon in the lower-left and authenticate.
• Configure the Content Caching service.
Shared content: store apps and software updates.
iCloud content: store iCloud data, such as photos and documents.
Share Internet connection: share this computer's Internet connection and cached content with iOS devices connected using USB.
• Switch it on. Click the checkbox on the left of the service name to enable it.
Keep in mind that content caching will download all content requested by any client device, so the service will consume vast quantities of storage space unless you limit the storage. You can inspect how much storage space is being used on your Mac by the caching service by clicking the Options button. You can also use Cocktail (Preferences > Caches > System > Content caches) to flush/clear content caches.
Preview is a great basic image editing application bundled with macOS, but recent versions have simplified the available image export format options down to JPEG, JPEG 2000, OpenEXR, PDF, PNG and TIFF. Or at least that's what you see on first glance.
It turns out you can still access all the traditional image format options from the Save and Export panels just by holding down the Option (Alt) key when clicking on the Format menu.
Holding the Option (Alt) key when selecting format reveals all possible image formats. You can use this to convert existing images to different formats, or to save the file as a less common format.
macOS High Sierra contains many new features and capabilities, but APFS (Apple File System) is certainly one of the biggest changes. Changing the primary file system used by the Mac is a big deal. And like any big deal, there’s a lot to understand about how APFS will work with existing Mac apps and services, including Time Machine.
In its current incarnation, the Time Machine app is mostly compatible with APFS; that is, you can back up an APFS formatted drive using Time Machine, as well as restore files from a Time Machine backup to an APFS formatted drive. However, there are some very important caveats that Time Machine users should be aware of.
Time Machine drives must be formatted in HFS+ (a file system released with Mac OS 8.1 in 1998 and found on every version of macOS since then). Time Machine uses the magic of hard links, a feature that HFS+ file systems have to catalog and keep track of which files in a backup make up the current version of an app, document, or directory.
APFS, on the other hand, does not support hard links. When you convert an HFS+ formatted volume to APFS, any hard links found during the conversion process are automatically changed to symbolic links, thus breaking your Time Machine backup into a collection of almost useless files.
Luckily, installing macOS High Sierra won’t automatically convert Time Machine drives to APFS, but it’s possible to accidentally change the drive’s format to APFS from within Disk Utility. You’d think Disk Utility would detect the Time Machine backup and stop you, but it doesn’t. You can also convert a drive to APFS without macOS warning if you use the Finder option to encrypt a drive in High Sierra (macOS will convert the format to APFS before encrypting the drive).
If you do accidentally convert a Time Machine drive to APFS, the Time Machine app will no longer recognize the drive as a backup drive. If you select the old Time Machine drive within the Time Machine app as a backup destination, you’ll be confronted with an option to erase all of the content on the selected drive and reformat it as HFS+.
Until Apple releases a new version of Time Machine that makes use of the APFS feature set, such as snapshots to replace file linking, your Time Machine backup must remain formatted as HFS+.