Episode #125 of the Stack Overflow podcast is here. We talk Tilde Club and mechanical keyboards. Listen now
103

Disclosing the MAC address in itself shouldn't be a problem. MAC addresses are already quite predictable, easily sniffable, and any form of authentication dependent on them is inherently weak and shouldn't be relied upon. MAC addresses are almost always only used "internally" (between you and your immediate gateway). They really don't make it to the outside ...


79

I think you should ask why they want to use the MAC address, not necessarily for privacy reasons; "why do you need the MAC Address?" I think it's a reasonable question to ask them. Firstly, they will have MAC addresses of all the individuals who connect to the WiFi. Any device connecting to the WiFi will reveal their MAC address, based on the ARP protocol. ...


71

Physically finding them is not easy. If you are really willing to catch them, buy a couple ESP8266 modules (search eBay for them), research this project a little, drop a couple modules around and you can probably find them. But will cost a lot of time, effort and some money. Even if you cannot physically locate them, you can play some tricks with them: ...


63

You can defeat your brother's access restrictions, either by a timing-attack or side-channel attack. In a timing-attack, you wait for a sufficient time, your brother will remove the MAC filtering for your device. If you cannot wait for the time-based attack to succeed, you can use a side channel attack and connect to the internet via an alternative channel,...


53

This is not a security risk. The router looks in its ARP table to find the MAC address of your IP address. The reason it can do this, is because you are connected to the router via layer 2 in the OSI model. The router simply looks up your IP address in the ARP cache to find its MAC address. A website on the Internet is not connected to your LAN and will not ...


42

So the question is how to find their physical address location based on the mac address? You can't, IP addresses and MAC addresses do not carry any location information. Your access point may be able to give information on the signal strength, which could be used as an indication of the distance between the access point and the device. But not all brands ...


41

MAC filtering is not a part of the 802.11 spec, and is instead shoved into wireless routers by (most) vendors. The reason why it's not a part of the 802.11 spec is because it provides no true security (via kerckhoff's principle). In order for wireless to work, MAC addresses are exchanged in plaintext (Regardless of whether you're using WEP, WPA, WPA2, or ...


33

For a school, having all student device MAC addresses (unique hardware identifier) is a way to filter out a lot of unwanted traffic from the LAN. Even if outside devices from non-students spoof a legitimate, student-registered MAC, the packets being sent over the network can still be captured, opened, and the user agents, and other system identifiers can be ...


29

The common, low-level attackers (i.e. people in their home) cannot efficiently spoof their IP address for TCP connection because they will not receive answers. Remember that IP routes packets based on the destination address, so if you send a packet with a fake source address, it may still reach the destination. Some routers may be offended at seeing a ...


27

They're requesting your MAC address because they're using MAC filtering to control access to the WiFi network. That does not in and of itself constitute the ability to see what you're doing when you're on the school's network, and certainly not when you're at home. If this is the only requirement, and they are not also requiring you to install things (...


26

Well, the school already has your MAC address since you've connected to their access points in the past. What they don't (necessarily) know is the association between your MAC addresses and your real name. If that concerns you, just use a different MAC while you are at school: ip link set dev wlp1 address XX:XX:XX:XX:XX:XX Pick a Locally Administered MAC ...


22

MAC address filtering is a very weak form of wifi protection: the MAC addresses of your devices can be easily eavesdropped with tools like wireshark the MAC addresses of their devices can be easily changed (OS dependent, but typically an option in Network Settings). MAC address filtering is annoying to maintain. You have to login to your router ...


22

A MAC address is a number used to uniquely identify your device on the local network segment. The address is (and needs to be) visible to everyone on the network segment, but because of how network routing works, is not normally visible to anyone else. Unless you take steps to change it regularly, your MAC address uniquely identifies your device. Someone ...


21

Change your WiFi Password - make sure it's strong. Make sure you are using WPA/WPA2 Check your "plugged in" devices. They show up in the MAC list as well, and just because something says "Android" doesn't mean it's a phone. Ensure your router's admin password is not the default. Just because they are on that list doesn't mean the device is still connected. ...


19

1: The ISP only knows the MAC addresses for the address of the hotel's router. It may store that, but who cares. The hotel could store mac addresses for connected devices, and many do for captive portal use, but that history is typically forgotten after only a couple of days. The only way to know is to ask the hotel. (they probably won't know how to access ...


19

You could change your MAC address to something different. If he simply blacklisted your MAC addresses, it should be sufficient enough to generate a random address. If he whitelisted his own addresses, you can change your MAC address to that of one of his devices. Note that if there are multiple devices using the same MAC address simultaneously, the involved ...


18

In short, the answer is no, you usually can't block based on MAC address. And if you could, it would be useless. To understand why, you must know a thing or two about how the internet works. Communication between devices is commonly done via the Ethernet protocol (wiki), and despite the source and destination being identified by IP, actual communication is ...


18

@Xander is partly right. Documenting your MAC address allows them to do one (or more, or all) of a few things: MAC Address Filtering The school may be using MAC address filtering to (try) to keep unauthorized devices off of the network. While this is easily bypassed, once an attacker knows an authorized address, it does make joining the network a bit more ...


17

There is no risk here. The Internet is not just one protocol, but a series of protocols that stack up on top of each other. The exact definitions of each part of the stack differ somewhat from person to person, but the two we're concerned about here are fairly well-defined: the link layer and the network layer. Depending on who you ask, these layers have ...


17

MAC addresses are tied to equipment manufacturers. So MAC address can tell you the vendor that produced the device that is accessing your network, and not a bit more. You can use that page for a lookup, there are probably many more out there: http://aruljohn.com/mac.pl Relying solely on whitelisting MAC addresses is an extremely bad practice security-wise, ...


14

The question in the original title of your post ("Can a website still detect my real MAC address even if I use different virtual machine each time I visit the website?") is different than the question in the body of your post. To the question in the original title: No, a website should never be able to "detect" your MAC address, under any circumstances. ...


14

The easiest way would be to just spoof your MAC adress. Just listen to the network, watch which MAC adresses are able to connect and then give your own device the same MAC adress.


13

I think there's a massive misundestanding about what a MAC Address is. Nobody should get worried about MAC address. Period. Unless the attacker is in the same physical network segment than you, a MAC is useless. MAC address never leave the local network, they are easily changed, faked or cloned, they are not unique even if they were meant to be (there are ...


13

One significant thing is that there are databases that, given a mac address, can give the longitude and latitude of a wifi router. Most try to make sure you can only get your own location, but anyone can drive around and scan for the right mac address. Skyhook wireless unofficial api CNET article on google maps' database Google maps official API Wireless ...


12

Looking at the OUI, it appears you have 3 Apple MACs connected, 1 Netgear MAC, and 3 unknown MACs. The Apple and Netgear MACs may be spoofed; please compare them against your own devices. Then, if you can, compare their traffic against the legitimate device's traffic to see if those MAC's are being spoofed. The unknown MACs are almost certainly spoofed. ...


12

Yes, software running on your computer can find your MAC address. If you have a malware infection, your MAC address leaking is probably not greatest of your worries (keystroke loggers, and RAM scrapers, and backdoors are a lot bigger worries). In general your MAC address isn't really secret (it is sent with every ethernet frame), but it could potentially be ...


11

I'm willing to bet that they don't actually identify the computer, they just send you a persistent cookie once you've successfully logged in, and as long as your browser returns that cookie, they know it's a previously used machine. You should be able to test this quite easily using something like Firefox's Web Developer toolbar which will let you both ...


11

The answer to your question would be: There is no way of tracing this back to a single person. At best this will provide you with circumstantial evidence. The only way to be get some kind of evidence would be to perform a forensic analysis of every single person registered at the hotel. And even then there would be no certain way of knowing if the person was ...


10

Four possibilities come into mind for your slow internet. Your neighbors are using your wifi (e.g., you are using weak security on your router like WEP or are using very weak guessable passwords - wifi passwords can be broken offline so you need strong passphrases, or your router has a backdoor your neighbors are aware of) Your neighbors are using their own ...


8

Most WiFi enabled devices broadcast their Mac address when probing for networks to join in the vicinity. By placing your own WiFi device in promiscuous/listening mode and utilizing a tool like Aircrack-ng, you can see and record all broadcast traffic enabling you to see if a device with a specific MAC address comes within earshot of your listening device. ...


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