diff --git a/ex3/README.md b/ex3/README.md new file mode 100644 index 0000000..82f5bd0 --- /dev/null +++ b/ex3/README.md @@ -0,0 +1,39 @@ +# Exercise 3 + +## Analyzing Darkspace Evolution + +>>> +Check results from [rep-14] again. Are they correlated? Think for a second +about the possible meaning of the analyzed time series being correlated. What +could be the reason why the drop in the number of unique IP sources after Jan +16 does not cause a proportional drop in the other signals? +>>> + +The results are mostly either strongly or somewhat correlated. Looking at the +different correlations, it could be that the drop happened because someone was +scanning the network or performing some kind of attack on a lot of different +hosts. This hypothesis is supported by the high correlation of unique +destination IPs with the amount of packets and the amount of bytes sent. It +follows that, since the unique source IPs dropped, one IP address had a lot of +outflow of traffic to a lot of unique destination IPs. + +>>> +Check results from [rep-15] again. Do the results make sense for you? Would you +expect a different ratio in a normal network (no darkspace)? +>>> + +In a normal network I would expect the ratio to be much closer to one, albeit +still higher than one. Thinking about my traffic at home, most requests have a +response associated with them and thus the ratio should be much closer to one. +This ratio is easily offset by doing a horizontal scan on the network for +example. + +>>> +You used the median in [rep-15], but you could have used the mean. Does it make +any difference? What's better in your opinion? When to use mean and when +median? Can you figure out pros and cons for both measures of central tendency? +>>> + +The median definitely makes more sense in this case since it has a strong +rejection of outliers. The traffic data is very diverse and spread out, meaning +that the mean would look very different from the median.