What does a MAC address mean? What is the difference between an IP address and an IP address? Let's explain the random MAC of a phone all at once

first time flipping through the router device list hoping to freeload the internet, what I saw was a string of 'Heavenly Book': 64:BC:0C:8A:11:22. What is this? Later, the speed limit failed, blocking failed, and the whitelist blocked my phone—all these strange issues were buried in this string of characters. It's called a MAC address. In this article, I'll explain the differences from IPs, tips for identifying devices, and the pitfalls of random MACs all at once.

MAC is the factory ID card, IP is the property management issue the address number

one device to go online, carrying two accounts with me. IP address is the address number, like 192.168.31.108, which is issued uniformly by the router's DHCP. The number is rented to you, and when the lease expires, you change the network segment or reconnect once, and the number may change. Who is issuing the order and for how long? I wrote about it in DHCP .

MAC address ID card. Twelve hexadecimal characters are written in 6 groups, for example: 64:BC:0C:8A:11:22, which are burned in the network card chip at the factory. A phone has one WiFi card, one MAC, and another Bluetooth; a desktop computer with a network card adds an extra number. In theory, this is the only one in the world—IEEE assigns each chip manufacturer a number, and when companies write into chips, they are not allowed to duplicate numbers.

moving house can be explained with a different analogy: when people move, the house number changes, but the ID number remains unchanged. My router has been moved from the 192.168.31 subnet to the 192.168.1 subsidiary, and my phone's IP has changed from 31.108 to 1.112. But the speed limit rules in the router still follow—because the router doesn't remember a house number, it's an ID card.

How to identify devices on a MAC: the first six digits are the manufacturer's code

The first 6 characters of

MAC are called OUI, which are the number range issued by IEEE to manufacturers, equivalent to a surname. 64:BC:0C is basically for Xiaomi devices, A4:C1:38 is commonly found in Espressif IoT chips, and there are plenty of you can find in vacuum cleaner cameras. The manufacturer name in the device list is found by looking up the router using the first six digits. If you want to check yourself, put the first six digits into macvendors.com query page, press Enter to get the manufacturer.

this trick works very well when you want to mooch the internet. In my for the equipment list of this Mercury, I wrote about three ways to identify people. The first is to check the manufacturer: for the dozen or so devices on the list, those whose vendors match the family's belongings are swept away, and the rest that can't be traced or unfamiliar with the manufacturer are questioned with special attention.

teach a faster trick: look at the second character . If it's one of 2, 6, A, or E, the MAC isn't a factory-burned real number, but a randomly generated 'local address'—nine times out of ten, it's a phone with a random MAC enabled. For example, the OPPO on my list that started with 72:3A:1C always couldn't find the manufacturer, but later I found out it was my mother-in-law's OPPO with a 'private address'. Conversely, the second digits are 0, 4, 8, and C, which are basically the manufacturer's real numbers. This one character is much easier than searching for a manufacturer for ages.

Why

routers recognize MAC but not IP: Bind to speed limits or block them—all depend on it

all the "device-by-device" functions in the router, all the underlying anchors are MAC. The reason is simple: IP drifts, but MAC can't. Power outages and reconnections, lease expirations—IPs can shift in an instant; As long as you don't open the random MAC, the MAC is the device's lifelong identifier.

static binding is to bind the MAC and IP tightly; printers, NAS, and cameras are essential. Otherwise, port forwarding often leads to the wrong device. binding method written separately. speed limiting is based on MAC limits, while the TV box competes for bandwidth and uses 50 Mbps downlink. blocking, disabling or closing the door with MAC is also key. Including the child control circle devices, it's still about MAC, Xiaomi parental control the repeated device pitfalls I fell into — it was MAC causing trouble.

this also solved a puzzle I had in my early years: after switching to a new router, how did the thieves on the blacklist come in again? Because the rules are stored in the old router's storage, they follow the machine, not the person. The device is still the same, the MAC hasn't changed, but the list was left in the old machine and not brought over.

Random MAC: A Good Move from Phone Manufacturers, the Nemesis of Router Functionality

first explain why manufacturers do this. Before 2019, every WiFi connected to your phone could record your real MAC. In malls and stores, you can set up a probe—your shopping route, how often you come, which store you stand at for ten minutes—all connected by this account. If your MAC stays the same, it's like your ID number is printed on your forehead while shopping. Therefore, starting from Android 10 and iOS 14, phones connected to WiFi default to randomly generated fake MACs, and the probe numbers are immediately invalidated. This feature itself is a good thing.

But many people have a misconception: they think the random MAC changes every time. No. each WiFi network is assigned a fixed random MAC—your home is a fake number, and your company is another fake number, each used stably. Only if you "forget" to reconnect or reset the network will it switch to a new number. So the way random MACs scam people isn't 'changing every day,' but rather 'you think it's A, but it's actually B.'

scam and the whole family suffers: the speed limit is the old vest, while others use the new vest to drive the full speed. checking for speed limit failures the number one reason; Once the whitelist is opened, their phones with new disguises are blocked outside; Parents keep the controls locked for a long time, but the child can still play with the device by changing identities; The DHCP address pool is also gradually being consumed by these "new devices."

How to choose the

switch? My method is simple: your home network, change it to 'Use Device MAC'; WiFi outside keeps random. If you have functions like binding, speed limiting, parental control, and whitelist, you can use a random MAC to eat. If you go to your phone's WiFi details page, open your current network details, turn off 'random MAC/private addresses,' and switch to device MAC. From then on, your phone will always have a number in your home. Connecting shopping malls and hotels, randomly opened, specifically to guard against probes. IoT devices like cameras and robot vacuums are basically genuine and are not affected by this issue.

MAC can rewrite: Filtering can't stop thieves, cloning can save dialing

say the MAC burns inside the chip, it can actually be rewritten at the system level. This one brings two consequences: one good, one bad.

problem is that MAC filtering can't stop knowledgeable thieves. The router's "MAC filtering/whitelist" works by allowing only MACs within the list. But if you really put in the effort, you can fake your computer's MAC as someone from your list, and the door will open. So MAC filters to block gentlemen, not villains. The right way to prevent anti-internet use is always a strong 16-digit password with WPS enabled. stance on anti-internet anti-internet use remains unchanged to this day.

good thing is that MAC cloning can save dial-up. Some carriers bind broadband accounts to the MAC of the first dial-up device during installation, so when you switch to a new router, no matter how you dial, the server is unresponsive. The solution is to clone the new router's MAC to the MAC of the old device. The carrier sees it's still an 'old acquaintance' and lets it through. The operation is done in four steps on the MAC address cloning page in network parameters, detailed in the error code .

take it personally: Most of the time you're facing something, it's MACs causing trouble

compile the above into a table, and when you encounter any strange items, check them first:

Here's the order: Step one, enter the device list, recognize the MAC of every device at home, and check the second digit—real or fake accounts are well known; Step two: If you have a Mac button function at home, turn off the random MAC on each device and clear out the insider at once; Step 3: If the speed limit binding fails, handle it according to the table above; Step four: If you can't dial the number after switching devices, try to clone your MAC; Step 5: Anti-internet anti-internet—don't rely on MAC filtering. Raise your password to 16 digits and turn off WPS—it's tougher than any list. MAC is something you can't see in daily life, but when something goes wrong, it's always because of it—spend ten minutes recognizing it, it's worth it.