3/2/2024 0 Comments Get mac address linux javaThis means the following are all examples of such MACs: x2-xx-xx-xx-xx-xx A locally administered MAC address has the second-least-significant bit of the first octet set to 1. The difference between these two types of MAC addresses is simply one bit. At this point it is important to point out that there are two different types of MAC addresses: Universally administered and Locally administered. While Python specifically doesn't have this issue it is possible that a heavy burden could be placed on the randomness of a MAC address. However, as I discussed, while 10 million combinations is high for an online attack, it is well within the range of offline attacks, particularly if GPU enhanced. This means that instead of 1 billion options per second, there are only 10 million possible options, but this is still at the high end of reasonable for most web-based attackers. As previously mentioned, the RFC doesn't actually require true nanosecond accuracy, instead it specifies 100 nanosecond intervals. We see that Python has historically, and continues to, correctly leverage nanosecond level accuracy. To validate this, we can look at the python UUID code. In reality, this appears limited to NodeJS implementations (classic). The major issue pointed out in the original blog post was that some implementations don't use the RFC specified 100 nanosecond intervals, instead using milliseconds. Given the small search space of the sequence factor (only ~16000 combos) the only real variability is introduced by the timestamp and MAC address. UUIDv1 draws its search space from a timestamp, a 14-bit random sequence factor, and a MAC address. This week we take a more in-depth gander at how Python decides which MAC address to use for UUIDv1/v2 as this is a key part of the 'security' of UUID. It's been a few weeks since I expanded the work on UUIDv1 security from a previous blog. I’ve decided to keep a record of my adventures. Every week, almost without fail, I come across one thing that confuses, entertains, or most commonly infuriates me.
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