Interview Question

Production Engineer Interview

-Menlo Park, CA

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What options do you have, nefarious or otherwise, to stop people on a wireless network you are also on (but have no admin rights to) from hogging bandwidth by streaming videos?

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5 Answers

2

This question is basically a way of ascertaining how much knowledge you have of the effect of distorting networking protocols in nonstandard ways. Everything from "ask them politely to stop" to "hijack their connection".

Anonymous on

3

set a dns server with the same MAC of real DNS server, forward all the "healthy" traffic back to real DNS, hijack the Domain related to video streaming.

Anonymous on

0

Anonymous on Apr 4, 2016: (but have no admin rights to)?

Tom Lobato on

0

1. Use airodump-ng to find the MAC address of the station with the most traffic to the AP. Use airreplay-ng to spam deauth packets to that station. Kinda the nuclear option, but low-effort, and they probably deserve it. 2. Arp spoof them into using you as the gateway and set sys.net.ipv4.ip_forward to 0. Another nuclear option, but implies some network speed cost to you as all of their upstream is going to hit your wifi card before getting dropped. 3. Arp spoof and allow forwarding, but DROP all packets destined to the IP address of the video server. More finesse, but depends on the IP for video to be static. Other filtering and tampering methods exist, DNS hijacking, malicious JS injection, the list goes on. This approach is more of network speed hit for you as you are a kink in the network. Packets are sent from the victim to the wifi router, (the layer 1 relay) to you, the "gateway" at layer 2, for you to have to filter and masquerade traffic back up to the router at layer 1 again. And back. Very costly. 4. QoS on the router if you have a fancy enough router. De-prioritize long running http(s) streams under everything else. 5. Block the MAC of the video stream client on the router. 6. Block the domain of the video stream server on the router.

rpgraham84 on

4

There are two methods: 1. Halt all the UDP traffic coming to your network, UDP does not do congestion control. 2.If it is TCP, unwrap each packet at the router and retransmit the packet after changing the window size(limiting it to a certain value) in the TCP header

Anonymous on

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