Chapter 3 Time-to-live Covert Channels - CAIA

Throughput (bits/s)
60
50
40
30
20
10
0
0.0 0.1 0.2 0.3 0.4 0.5
Packet reordering (%)
CHAPTER 3. TIME-TO-LIVE COVERT CHANNELS
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Throughput (kbits/s)
8
6
4
2
0
0.0 0.1 0.2 0.3 0.4 0.5
Packet reordering (%)
Figure 3.23: Throughput depending on packet reordering for CAIA (left) and Leipzig (right)
for 0.1% packet loss
Capacity percentage
100
90
80
70
60
50
l=0,
r=0
l=0.1,
r=0
l=0.5,
r=0
l=1.0,
r=0
Packet loss (l) and reordering (r) (%)
l=0.1,
r=0.1
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Figure 3.24: Percentage of capacity reached for the different modulation schemes and the
different packet loss and reordering settings averaged across all traces
We also measured the average block decoding speed of the receiver, which is defined
as the length of a data block in bytes divided by the average decoding time of blocks. The
differences between different modulation schemes are negligible, but there are significant
differences between the different traces. The results show that even for the experiments
with the highest error rate the decoder is still much faster than the actual throughput of
the channel (see Appendix B.9).
3.5.6 Throughput – testbed experiments
In the testbed experiments we measured the throughput of the covert channel across a
real network for different types of overt traffic. The covert channel was encoded in a
single overt traffic flow. This setup is representative for a scenario where the overt traffic
68
l=0.1,
r=0.5
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