nmap -sn 192.168.0.1-255
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.
https://serverfault.com/questions/462178/duplicate-mac-addre...
what happens depends on your LAN setup, but generally its a fail.
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.
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.
The clock was probably doing the "correct" thing when it got a TCP packet for a connection which it didn't recognize and sent back an RST, which caused the client to abort.
> kind of problems that teaches you to question your assumptions
Yep. I learned a lot from dealing with large layer-2 networks (commonly running on hardware not suited for the task). Mostly I learned to never run large L2 networks.
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.
I know Windows gets upset when that happens but the network seems to still work.
sync boot
In-room, you get free internet access, but in the windowless ballroom with spotty cell-service, there's nothing available for free.
"Follow the money"
For extra fun, consider how phone bills attempt to "pass through" their own tax obligations, which have little to do with your own incremental usage, in the form of 'recovery fees' tacked onto bills. I suspect we'll eventually see those creep into all kinds of transactions, especially among other monopolistic/oligopoly businesses where you have little if any choice.
That's basic price elasticity of demand and entirely unsurprising. When something costs 10% more, people buy less of it in general.
We also buy more things priced at $99.99 than at $100.00, which is more of the psychological trick than it is rational price elasticity.
Hard to advertise to a wide audience when the final price after tax is one of 12 different prices depending on where they live.
I don't know of any US businesses other than waffle house that always include all taxes in the listed price, however.
Regardless, I'm not sure why people consider it such a big deal. It's consistent across the board and it's relatively basic math to estimate what the total would be.
I've lived in places that do it both ways and it's a non-issue.
I think the norm is to show whatever price you want, with some countries banning that for fairly obvious reasons.
I just switched to my cell phone data if the wifi was too slow.
There's still some stragglers though, offering "basic" access free but charging for higher data limits, faster bandwidth, more devices. You can often get the higher plan just by signing up for the hotel's loyalty program.
From my point of view, free WiFi became normal when it became less important because of affordable mobile internet.
From the point of view of the hotels it was about recovering their missing income after customers got mobile phones and stopped paying half a dollar per minute for using the hotel phones. There was a period when both mobile roaming and hotel WiFi was expensive, so I often went out from my hotel room and bough a local SIM-card to get internet access.
What annoys me most, is that only when I finally could get a laptop that would work a full transatlantic flight on one charge, then suddenly airplanes all got power outlets.
I always wondered if there was a way to further exploit that.