Slashdot Mirror
Researchers Warn Computer Clocks Can Be Easily Scrambled Via NTP Flaws (networkworld.com)
alphadogg writes: Researchers at Boston University said this week that they've found flaws in the Network Time Protocol (NTP), a 30-year-old Internet protocol whose security shortcomings could undermine encrypted communications and even jam up bitcoin transactions. The importance of NTP was highlighted in a 2012 incident in which two servers run by the U.S. Navy rolled back their clocks 12 years, deciding it was the year 2000. Computers that checked in with the Navy's servers and adjusted their clocks accordingly had a variety of problems with their phones systems, routers and authentication systems.
There is at least one alternative out there, and reason to use it.
have an option for ignoring server updates if the time differential is too great.
RFC 5906
don't screw around with options once they get the thing initially functioning.
Isn't Eric Raymond in the middle of a major rewrite of the NTP software, with emphasis on security?
systemd automatically knows what time it is, but it'll only tell you in binary.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
So design things to not require synced clocks.
It's not like you couldn't include your idea of your local time (whatever it is) in your NFS requests, and then have the server take its idea of its local time, generate a delta, and apply that to all the timestamps that you are trying to set on a file. Or conversely, when you do a stat, the server could include its idea of the local time, the client could use that to generate a delta vs. its own idea of local time, and apply that delta to the time being reported up from the kernel to user space.
The whole idea of having to synchronize clocks between machines is rather moronic. When you have a billion mechanical computers wandering around in your body with robot bodies to e.g. fight a nasty cancer, do you really think there's going to be enough spare CPU cycles, RAM, or communications bandwidth for them to run NTP requests around to each other?
I recently fielded a request from someone who was building an embedded device; the trick was, it was going to be pre-programmed, then deployed everywhere, and not have local time beacons (i.e. it couldn't access local beacons, such as local cell towers, which send out "time is now" broadcasts). The question was: "How do I sync the time to the local time?".
My response was "Why?".
The reason finally boiled down to wanting to put the time in log files, and to display it on an LCD.
There was no reason for either of these: if the devices are Internet connected, just grab an HTTP header by hitting a known HTTP server, and log in UTC, since the time in the header will be reported as a UTC time + a zone delta. For the display: why the hell do you need to display the time on the small LCD? Because it was the only neutral thing he could think of to display on the LCD. "Can't I just look at my watch/iPhone/VCR/microwave/refrigerator/dishwasher/clock? Or just display it in UTC? Or display a PacMan animation instead of a clock?". "I guess so".
Problem solved with no need to sync clocks.
Non-synchronized clocks are only a problem if you let them be a problem/make them a problem.
It appears to me that all the NTP patches and all the NTP alternatives are for UNIX or Linux systems.
I use SocketWatch on Windows 7 to synchronize my PC clock with external time servers around the world. I have it set to run every hour. It warns me whenever an adjustment to my PC clock is excessive (using my definition of "excessive").
The questions are: How do the reported problems with NTP affect me. Or do those problems only affect time servers?
Yes, I know SocketWatch is no longer being maintained. The developer is going out of business and will soon stop distributing it. As long as it works for me, I hope to keep using it.
So design things to not require synced clocks.
They do when that is a sane thing to do. Sometimes a precise notion of time isn't important. But many activities are impossible without a rather precise determination of the time across multiple devices.
It's not like you couldn't include your idea of your local time (whatever it is) in your NFS requests, and then have the server take its idea of its local time, generate a delta, and apply that to all the timestamps that you are trying to set on a file.
The only way to ensure the local time on your clock is correct is to synchronize with another clock. A clock providing arbitrary time stamps is worse than useless. In fact for many activities what you suggest would lead to accidents, fraud and all sorts of confusion.
Any time you have a measuring device where you care about its accuracy you have to compare it to a reference standard. That's why we have highly accurate atomic clocks maintained by standards organizations to calibrate our clocks to.
Non-synchronized clocks are only a problem if you let them be a problem/make them a problem.
Sorry my friend but that's simply not true for a lot of problems.
The mentioned TLSdate isn't a NTP replacement.
It openly admits is roughly only good for a <1-5 second accuracy. That's crap. A typical NTP setup can easily maintain ~10-15 millisecond accuracy using public stratum 2 or 3 NTP servers from the Internet.
Sure, tlsdate is a simple, secure rdate replacement, and while many people without precise timing requirements it is good enough, it is simply not suitable for a huge range of applications that are time sensitive, or are timing / synchronization critical.
I feel that this isn't a real apk post.
If you're relying on a Tardis for accurate time, you're in for a world of pain.