14 ms·
I used to do the same thing at hotels. Still often works. nmap -sn 192.168.0.1-255 To find everyone on the network, then start spoofing each of their MACs u
by KMnO4 3y ago
I used to do the same thing at hotels. Still often works.
nmap -sn 192.168.0.1-255
To find everyone on the network, then start spoofing each of their MACs until you find one that works
- savrajsingh 3y agoI should probably know the answer, but what happens when two devices have the same MAC address?
- queuebert 3y agoOnly one way to find out.
- commandlinefan 3y agoNo way to tell for sure, but I can only assume that he had actually hijacked somebody else's connection and the other person's device stopped working for them. I sure wasn't going to stand up and ask the plane if anybody had had their internet plan hacked...
- _joel 3y agoBuy a plan then clone the mac of that device, white hat it. Might have killed a bit of time (unless you needed sleep) :)
- eru 3y agoThat's fun, but why not just buy a plan for one device, and then start a wifi hotspot on that device to share the connection?
- ahoka 3y agoThat’s not how it works, but probably made someones browsing experience worse.
- Cpoll 3y agoI should probably know this too, but I'll speculate wildly instead. MAC is Layer 2, IP address is Layer 3. One way or another, the packet destined for the person you're spoofing will end up at your computer and work its way through the layers. From there, if it's a TCP/IP packet, I think it'll get filtered out at Layer 4 (transport) because your computer wasn't one of the parties that initiated the TCP connection (the sequence numbers won't line up, etc). Packets being broadcast to multiple machines is common enough in various network setups, it's up to the individual machine to decide whether to process or drop the packet.
- _joel 3y agoARP entered the chat
- rolph 3y agothis seems to be a decent answer written up ready to go. https://serverfault.com/questions/462178/duplicate-mac-address-on-the-same-lan-possible https://serverfault.com/questions/462178/duplicate-mac-addre... what happens depends on your LAN setup, but generally its a fail.
- AdamJacobMuller 3y ago"it depends, nothing good" Network devices forward (switch, more technically) packets to and end device based on an internal MAC table (send packets for DE:AD:BE:EF to interface ge-0/0/0.0) and most devices populate their MAC table simply by looking at input packets and sending the "next" packet for that MAC address out the "last" received interface. If two devices in a network have the same MAC address, they will effectively "fight" for control of the packet flow. You can win that fight by sending a lot of packets. In practice, the other person is going to get annoyed and give up. There are lots of technology which avoid this issue now, but the two primary ones are 802.1x (used in corporate/government environments) and DHCP snooping which can be much more broadly deployed. 802.1x is very complicated and I won't go into it, but, DHCP snooping works by limiting L2 forwarding (MAC table population) to only what the DHCP server says the end device should have and it does this just by inspecting the DHCP replies (no custom protocol) with some vendor specific extensions on the DHCP server side for complex scenarios (you can even do things like put ports in a specific VLAN based on the DHCP reply). This works fine on a physical layer and most hotels are probably using something similar now (less for malicious abusive reasons, though that's a thing) but also just to work around poorly behaving devices and to reduce customer complaints. If you care (and have a modest amount of money) MAC and IP spoofing are dead on the physical layer. For the wifi layer, very similar stuff exists in high-end gear (Rukus/Cisco) and is starting to trickle down to prosumer level gear like unifi. If you care (and have serious cash for Rukus) MAC and IP spoofing are also dead on the wifi layer.
- EvanAnderson 3y ago> "it depends, nothing good" Fun anecdote from the early 2000's re: duplicate MACs: Embedded IP time clock kept intermittently barfing out frames with the source MAC addresses of other devices on the network. The switch would update its MAC table and direct packets to this device. The Customer's AS/400 would kill all remote terminal sessions when the clock ended up w/ the AS/400's MAC. (They were doing a layer 2-based connection to the AS/400-- APPN, I believe it was called... Ugh, it was temperamental and didn't like any layer 2 "hiccups".) MAC addresses flapping between ports is one of those "breaking the laws of physics" kind of problems that teaches you to question your assumptions. Gear with a crazy brain can do anything it wants to and it doesn't care about your assumptions.
- spmurrayzzz 3y agoIt more or less turns into an ARP cache race, only one device is gonna win. You can do some tricks with gratuitous ARPs as well for "dumber" networks, but more sophisticated setups usually have some broadcast ARP filters that are tied to an auth layer (radius, 802.1x. etc) and will drop broadcast frames from un-authed hosts.
- angry_octet 3y agoThat greatly depends on whether the medium is broadcast (like a radio) or broadcast-like (a shared copper wire) and if it has CSMA/CD logic. Many of the replies are losing that detail and thinking of how it would effect a 1000base-T network, which maps MAC addresses to specific ports. For a broadcast network, the answer could be 'nothing' in the sense that both receivers would get the same traffic. The IP stack would then throw away packets destined for the other computer unless they were UDP broadcast or multicast, and even then it would only notice if someone was running Wireshark. Advanced wifi devices/meshes will use beam forming and mesh allocation and might degrade if there were MAC duplicates, but I think they will generally operate in a non-exclusive basis due to end point movement and fading, so both computers will get a good data rate. In summary: it's fine.
- colanderman 3y agoCan't this often result in the two machines RSTing each others' TCP connections, depending on firewall settings?
- angry_octet 3y agoGreat question. It could, but there is a strong chance that the true recipient has already partially or fully ACKd the segment, thereby changing the sequence number and preventing a reset.
- sznio 3y agoSince Wi-Fi is a broadcast medium, shouldn't it not matter? With a switch it would break things because MAC tables, but a Wi-Fi AP is a hub. Each device will receive packets for both devices, sure, but will that break things? I know Windows gets upset when that happens but the network seems to still work.
- time4tea 3y agoISTR SunOS4 panic if it saw duplicate IP address on the network. sync boot
- lupire 3y agoDoes that work if both of you are trying to send/receive packets at the same time?
- fragmede 3y agoYeah, the client OS will reject the "bad" packets destined for the other device as unknown.
- system2 3y agoWiFi signal is received by both. Packages are ignored if they are not requested by either one of the systems. You can also receive anyone else's packages while you are using your internet but ignoring the ones you don't need. (If interested try aircrack-ng.)
- ahoka 3y agoOnly if it’s unencrypted, of course. Rarely the case nowadays.
- ruune 3y agoIf it's important but you got time, you could always save the packets and crack them when quantum computing comes out for consumers. You have to wait a couple of decades probably, but maybe it's worth it
- pests 3y agoNSA is already taking care of that in Utah.
- angry_octet 3y agoYour computer will still receive the packets from the radio layer, it just won't have the right key to decode the other recipient's traffic.
- 3y ago
- louison11 3y agoThis is what I did about 7-8 years ago on flights when I was still a reckless teenager. Would just wait for people to buy the plan, then spoof their Mac address. There was also a specific airline, although I can't remember which one, which let me in for free without MAC spoofing - by using a Google Cloud VPN I had previously set up. The paywall was essentially blocking all IP ranges except for Google servers for Google Analytics.
- ApolloFortyNine 3y agoSimilar is probably possible on cruise ships, I noticed on Carnival you could still get notifications from discord (I assume because most android notifications go through cloud messaging and it's required for their own app to work without internet).
- Scoundreller 3y agoTook an airline that required an app to pay to connect… but also opened up a window of a few minutes of open access to let you download said app from the iStore. I always wondered if there was a way to further exploit that.
- withinboredom 3y agoIIRC (assuming it was the same airline), it didn't close existing connections once the time ran out, so you'd just ssh to a server and proxy through that. When/if the connection dropped, you'd just change your mac address and start over.
- pantalaimon 3y agoI’ve never been at a hotel that charged for WiFi - is that a US thing?
- Spooky23 3y agoConference hotels often soak the companies with booths for internet access. One place I did for my company demanded $1500 for 3 days of internet access for up to 5 devices. In-room, you get free internet access, but in the windowless ballroom with spotty cell-service, there's nothing available for free.
- rootbear 3y agoI’ve also seen the opposite, where in-room Wi-Fi was charged, but in the hotel’s function spaces, it was free. The economics of this are confusing, at best. I have also had the situation where the in-room wi-fi was so slow that using my phone as a hot spot was faster!
- Spooky23 3y agoSometimes that because the operator got hosed in a contract with a network provider. I used to see that a lot in full service hotels.
- reichstein 3y agoIf they give you free internet in your room, you won't pay for their pay-TV. Especially the kind you won't be watching in public areas. "Follow the money"
- louison11 3y agoYes. You often also have to pay for parking in many places. The price you see online is rarely what you pay for. But that's part of the culture, it's the same for restaurants, online purchases etc.
- lukas099 3y ago
- SileNce5k 3y agoThis is what I used to do at home when my dad would turn off my internet access (by whitelisting MAC-addresses. Before that he blacklisted MAC-addresses, but I just used the built in way to change it with each connection on windows until he found out.). My mom rarely used her PC so I would just change my address to hers. It worked until she had to use it and at that point none of us could access the internet.
- politelemon 3y agoHow would you get the MAC address from the IP address?