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1500 questions
7
votes
2 answers
How is the Groupwise Transient Key used in WiFi networks?
In Wifi WPA, I understand that during association, a 802.11 client and AP negotiate a Pairwise Transient Key (PTK), using which the Groupwise Transient Key(GTK) is provided to the station.
I understood recently that all communication from/to this…
Sush
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7
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3 answers
Need help understanding how packets travel across the internet
I've been learning about networks recently at a new job, and I did a presentation on what I've learnt so far. When I was describing the relationship between the datalink and network layer, I mentioned that datalink handles the hops while network is…
jwoff
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7
votes
1 answer
Auto-QOS configuration for Cisco network
I have a network with Cisco switches, Cisco IP Phones and video traffic. I want to add QoS markers to my traffic but I don't want to do it manually.
Ideally I want to use Cisco's auto QOS features but I'm not sure where I should add the…
Jeremy G.
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7
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2 answers
Why is internet speed called Bandwidth?
Why do we refer to our internet speeds as "bandwidth" with units of measurement like "10 Mbps"?
As I understand it, Bandwidth is, as the name implies, the width of the frequency band, typically measured in Hertz. So if you had a signal with a…
Andrew
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7
votes
2 answers
Mitigating 802.1x bypass by transparent bridging
The talk DEFCON talk "A Bridge Too Far" details a means to bypass wired 802.1x network access controls by setting up a transparent bridge between a genuine machine and the network. Once authentication is performed, the transparent bridge is free to…
Cybergibbons
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7
votes
7 answers
Why is classful addressing considered waste?
I am trying to understand the addressing strategies. But there is something which I can't grasp. Maybe I am missing a very basic point, if so, I am sorry beforehand.
From my researches, let's say, if a company wants 100,000 IP addresses for their…
Hmerac
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7
votes
2 answers
What does the output of this tcpdump mean?
Bellow I show the output of my tcpdump
What does the first two mean lines means(what are all the question-marks meaning is this a sign of a intruder)?
I am especially interested in the meaning of what this mean:
PTR (QM)? _airplay._tcp.local.
PTR…
jennifer ruurs
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7
votes
5 answers
Cisco: monitoring users input
Is there a way to monitor a user's input on a cisco device?
Clarification: the commands a user have entered as in configuration mode AND normal mode. (especialy normal mode. Configuration mode can be done with "show history").
Bulki
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7
votes
1 answer
Is there an Assignment Window (AW) for IPv6 in the RIPE region?
In IPv4, newborn LIRs must seek approval from the RIPE NCC before assigning a prefix larger than a certain size to end users.
As time goes (and RIPE see that you fill in the RIPE database correctly), this certain size increases upon being big…
Benjamin A.
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7
votes
2 answers
Why is RTS/CTS optional for IEEE 802.11?
In wikipedia it is stated:
Request to Send (RTS) frame: The RTS and CTS frames provide an optional collision reduction scheme for access points with hidden stations. A station sends a RTS frame as the first step in a two-way handshake required…
dsax7
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7
votes
4 answers
Why is the Ethernet Connection Symmetric?
I know that cable connection (DSL) is asymmetric, there is a certain bandwidth on the channel, and for a better user experience, they allocate a bigger portion to the downstream. I suppose Ethernet cables have a certain bandwidth as well, or…
Ninja Bug
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7
votes
1 answer
Do we send ack frames in ethernet? if not then how does a router know if its neighbors are down or not?
So first off, do ethernet sends ack frames or not?
if it doesn't : then how does a router know whether its neighbors are down or not?
if it does : then is it cumulative ack with an ack timer or one ack per received frame?
I'm asking this because in…
John P
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7
votes
3 answers
Does Cell Phone use Public or Private IP address?
Does mobile phone/cell phone get a private IP address or public IP address?
If the cell phone gets a private IP address, I assume that the telecom operator uses carrier grade Network Address Translation as traffic leaves the operator's network, is…
user34639
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7
votes
2 answers
Ethernet's frame format, length or EtherType?
Ethernet defines a 2 byte header for the payload's length in its frame format.
This header has an ambiguous meaning:
if smaller than or equal to 1500 it represents the payload length.
if greater or equal 1536 (0x600) it is to be considered as an…
MFranc
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7
votes
2 answers
Monitoring without Port Mirroring
A quick overview of the problem
We've been experiencing some issues with our bandwidth usage lately which I fear may be due to misuse (whether intentional or not) of our internet in the office. I want to be able to monitor the network traffic to see…
aaroncatlin
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