The choice of a specific sampling strategy requires a broad and clear understanding of the capabilities and limitations of each technique and the specific behavior of the network on which it will be applied. Therefore, to properly consider a greater number of traffic scenarios and specific needs this tool provides a wider collection of packet sampling techniques, presented in the table.
| Selection Scheme | Trigger |
|---|---|
| Systematic Count-based | position |
| Systematic Time-based | time |
| Simple Random | position |
| Additive Random | position |
| Multi-Adaptive | time |
If you’re running on Linux, you probably already have GPG (GNU Privacy Guard) installed. If you’re on Windows or OS X, you’ll need to install the appropriate version for your platform.
- If you’re on a PC running Windows, download and install GPG4Win from here.
- If you’re on a Macintosh running OS X, download and install GPGTools from here.
Since Windows does not have the native ability to calculate SHA1 checksums, you will also need a utility such as Microsoft File Checksum Integrity Verifier or Hashtab to verify your download.
Once you’ve installed GPG, you’ll need to download and import a copy of the my key. Do this with the following command:
$ gpg --keyserver hkp:https://keys.gnupg.net --recv-key CE994164
Your output should look like this:
gpg: key CE994164: public key "Ricardo Costa Oliveira <[email protected]>" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
Verify that the key is properly installed with the command:
$ gpg --list-keys --with-fingerprint CE994164
The output will look like this:
pub 4096R/CE994164 2016-01-13 [expires: 2020-01-13]
Key fingerprint = 10C9 CEE5 72EE 77A2 C950 39AA 4A02 4A0C CE99 4164
uid [ultimate] Ricardo Costa Oliveira <[email protected]>
sub 4096R/C49636FA 2016-01-13 [expires: 2020-01-13]
You’re now set up to validate your download.
This method does not rely on the integrity of the web site you downloaded the file from, only the official development team key that you install independently. To verify your file this way, you will need to download three files:
- The ZIP file itself (e.g. Packet-Sampling-for-Online-Classification-of-Encrypted-Internet-Traffic-master.zip)
- The file containing the calculated SHA256 hash for the ZIP, SHA2SUM
- The signed version of that file, SHA2SUM.asc
Before verifying the checksums of the file, you must ensure that the SHA2SUM file is the one generated by me. That’s why the file is signed by my official key with a detached signature in SHA2SUM.asc.
Once you have downloaded both SHA2SUM and SHA2SUM.asc, you can verify the signature as follows:
$ gpg --verify SHA2SUM.asc SHA2SUM
gpg: Signature made Mon Jun 12 23:30:00 2016 WEST using RSA key ID CE994164
gpg: Good signature from "Ricardo Costa Oliveira <[email protected]>" [ultimate]
If you did get the “Good signature” response, you can now be assured that the checksum in the SHA2SUM file was actually provided by the development team. All that remains to be done to complete the verification is to validate that the signature you compute from the file you’ve downloaded matches the one in the SHA2SUM file. You can do that on Linux or OS X with the following command (assuming that the file is named “Amostragem-de-Pacotes-para-Classificacao-Online-de-Trafego-Internet-Cifrado-master.zip” and is in your working directory):
$ grep Packet-Sampling-for-Online-Classification-of-Encrypted-Internet-Traffic-master.zip SHA2SUM | shasum -a 256 -c
If the file is successfully authenticated, the response will look like this:
Packet-Sampling-for-Online-Classification-of-Encrypted-Internet-Traffic-master.zip: OK
Once you’ve downloaded and verified your file, you can proceed.
As simple as providing the selection scheme. Here goes the help:
$ ./sampling --help
Packet sampling for online classification of encrypted internet traffic.
Ricardo Oliveira '16
Usage: ./sampling [options]
Options:
-h,--help show this help message and exit
General options:
-v, --verbose Verbose mode.
Default: brief
-f FILE, --file FILE
Open a file with previous captured traffic.
-o FILE, --output FILE
Specifies the directory where the captured
traffic is saved in a pcap file.
-p , --sniffer
No selection scheme is applied to the captured traffic.
-s INTERVAL, --systematic_count INTERVAL
Sets the interval between samples to INTERVAL.
-t INTERVAL, --systematic_time INTERVAL
Sets the interval between samples to INTERVAL ms.
-r N, --simple_random N
Sets the interval between samples to
[0 , 2*sampling rate-2].
-a N, --random_additive N
Specifies the average sampling rate.
On average each sampling will occur every N packets.
-m , --multi_adaptive
Default values: min next sample size = 10000 ms
max next samplesize = 500000 ms
min interval between samples = 10000 ms
max interval between samples = 500000 ms
window size = 10
The network traffic used here was captured in a controlled environment and can be downloaded here.
$ ./sampling --file captured-traffic.pcap --output /user/home/Desktop/ --multi_adaptive
Statistical Parameters
First Packet Fri Aug 5 18:48:03 2011
Last Packet Fri Aug 5 19:06:19 2011
Elapsed Time 1095.917873 s
Overhead :
Number of packets captured : 1890723
Number of packets selected : 422516 (22.34680 %)
Appropriate sample size : 32971
Total Data Volume : 1393631968 Bytes
Sampled Data Volume : 311384916 Bytes
Number of Samples : 42535
Throughput Estimation:
Total Throughput : 1271657 bytes/s
Sampled Throughput : 284131 bytes/s
Total Peak to average : 1.280
Sampled Peak to average : 1.285
Correlation : 0.999
Relative Error : 0.001
Mean : 737
Standard Deviation : 682.867