Hi everyone! I'm Mridul. I wish to apply for the Exitmap improvements project mentored by Dr. Philipp Winter for the Google Summer of Code 2016. My current IRC handle is mtyamantau.
Contents -------- 1. Introduction - About myself and experience with Tor 2. Exitmap - Current progress and questions 3. GSoC - Rough proposal structure and questions
1. Introduction - About myself and experience with Tor ------------------------------------------------------
I'm Mridul Malpotra, currently in my senior year pursuing bachelors in Computer Science from IIIT Delhi, India. My interests primarily lie in computer networks and network security, specifically anonymous networks like Tor and I2P. Through my now 1-year long undergraduate thesis work under Dr. Sambuddho Chakravarty, I have had exposure to the Tor network, relevant literature and some related projects, which helped me better understand and appreciate the current research and development going on.
My work involved manually setting up testbeds through testing Tor networks on our institute intranet as well as on PlanetLab (for those wondering, I had recommended Chutney and Shadow). The current private testing Tor network is running on a PlanetLab slice (iiitd_mridul2) with ~170 nodes globally and 3 directory authorities. I used the control protocol through the Stem library to help in multiple circuit creation and stream attachments for measuring performance of a software over Tor.
I have also had experience with open source software, by contributing to the Non intrusive load-monitoring toolkit (NILMTK) which is based on Python and Pandas. While working there, I helped contribute code for additional features, fixed a few bugs and also worked with a few of Python's package management and documentation systems. Relevant links: github.com/nilmtk/nilmtk/commits?author=mridulmalpotra
2. Exitmap - Current progress and questions -------------------------------------------
I recently read about Exitmap in the 'Differential Treatment of Anonymous Users' paper by Khattak et. al. The use case for fast automated scanning through Exitmap to evaluate ~1000 exit nodes was really interesting. On top of that, it fitted my use case of testing a particular software's performance over Tor. Familiarizing myself with the source code, I think I understand the basic layout for how the scanner works and appreciate the modularity of task executions. I followed the project's progress on github and have read the 'Spoiled Onions' paper by Winter et. al.
In the coming 2 days, I plan to tinker around more with the code, discuss concerns, issues and/or suggestions if any, and get myself properly familiarized with the codebase. I also have certain ideas regarding what modules could be added and improvements made, some of which I have mentioned in the next section. I will also be reading the tech report on Exitmap and would be grateful if you can recommend any other resource(s) that I should be referring to.
Lastly, I had a few queries related to the project and/or paper and apologize for the naivety in the questions if any. a. How was the bifurcation between stand-alone and same-process modules decided? Are there any advantages to allow for multiple forked processes for specific modules? b. For testing active attacks, can there be modules developed keeping other cleartext protocols like SNMP and Telnet in mind? Alternatively, is there a way to determine what protocols are being used over Tor and their popularity? c. How is Exitmap being crowdsourced currently? I'm interested to know how data is being collected from volunteers running the scanner.
3. GSoC - Rough proposal structure and questions ------------------------------------------------
Here I am listing the possible objectives that my project will be focusing on. I request your feedback and comments on the chosen topics and their descriptions.
1. Achieve autonomous scanning in Exitmap with periodic scans that, based on a certain algorithm, fetches relay descriptors and automates various subtasks for consistent data collection and verification. The main challenges that I expect will be intelligently recognizing which tasks to automate and when, and making the entire background process execution efficient in resource consumption.
2. Emulating multiple user interaction in individual modules and in Exitmap overall to provide indistinguishability to Exitmap from regular users. I will try to explore libraries for this purpose like Splinter with Selenium or BeautifulSoup with Requests that help dynamically interaction with the web resource. The main challenges that I expect will be to scale this automated testing alongside the running asynchronous jobs and making the entire scans look like genuine user interactions. Any suggestions on better ways to do this will be helpful.
3. Making the codebase more robust by adding unit test cases. I plan on using either the plain unittest/unittest2 framework or nose/nose2/pytest tools or any other alternatives that I may find or be recommended. I plan to simultaneously write the unit test cases for new code added and improve upon the exiting testing programs.
4. (Optional) I read from the mail threads on the tor-dev mailing list that the code needs to be converted to be Python3 compatible. Would like your opinion on whether it is a viable option and if it is possible, would like to include this in my list of tasks.
5. (Optional) If I can spare time in the milestone timeline and if discussion leads to some clarity, I would like to add another module for more cleartext protocols that could be implemented like SNMP or Telnet. I am also looking at possible local to remote attacks that are active at the application layer and could be tested in Exitmap. I'll update if I find anything.
Next, I am drafting a week-wise timeline of what I plan to do over the duration of ~3 months. I will be dividing task 1 and 2 before and after the mid-term, with the optional tasks done in either of the slots and testing done alongside for everything. This is to ensure incremental milestones that can be useful to the community as I develop. Also, as I gain clarity on my objectives, I plan to refine this timeline to a week-wise format with buffers placed accordingly and present it in 2 days time.
Lastly, I would appreciate any suggestions, criticism or feedback on this proposal regarding content, volume or specificities. I am looking forward to contributing to the Tor Project organization and interacting with developers here.
Thanking you, (long mail I know, sorry) Sincerely,
On 3/18/16, Mridul Malpotra mridul.malpotra@gmail.com wrote:
b. For testing active attacks, can there be modules developedkeeping other cleartext protocols like SNMP and Telnet in mind?
Tor only supports TCP of course, however any cleartext application protocol using it is subject to snooping / modification. HTTP, POP3, NNTP, etc. And if the cert is MITM or server faked, so is TLS. A map to a honeypot of passwords [telnet pop3 ...] would be fun.
Alternatively, is there a way to determine what protocols are being used over Tor and their popularity?
That might guide which protocol to develop module for, along with thinking of what payoff for snooping / modification that proto is. Note tor claims such traffic analysis research is likely too sensitive to conduct, even though people privately conduct it all the time.
Hi Mridul,
Thanks for your interest in exitmap.
On Fri, Mar 18, 2016 at 11:26:01AM +0530, Mridul Malpotra wrote:
I will also be reading the tech report on Exitmap and would be grateful if you can recommend any other resource(s) that I should be referring to.
Don't bother reading the technical report. The PETS paper that you've already read is the most recent version.
a. How was the bifurcation between stand-alone and same-processmodules decided? Are there any advantages to allow for multiple forked processes for specific modules?
Do you mean the modules that are written in pure Python versus the modules that use external tools? Generally, we prefer to have pure Python modules, but in some cases it's more convenient and practical to run an external tool, say openssl, and parse its output.
b. For testing active attacks, can there be modules developedkeeping other cleartext protocols like SNMP and Telnet in mind? Alternatively, is there a way to determine what protocols are being used over Tor and their popularity?
Yes, you can certainly write SNMP and Telnet modules. Depending on what particular attack you are trying to expose (e.g., credential sniffing, content injection), the complexity of this can range from straightforward to quite tricky.
At this point, we have no privacy-preserving way to measure port popularity.
c. How is Exitmap being crowdsourced currently? I'm interested toknow how data is being collected from volunteers running the scanner.
A bunch of people, including myself, occasionally run exitmap. Some of these people wrote their own modules, which is great, because simply re-running the same modules wouldn't be all that useful. If somebody catches a bad exit relay, we report the result to bad-relays@torproject.org.
You can see that the process is informal, which is problematic because scans are not archived centrally. It would be neat to have a server that accepts incoming scan results, archives them, and provides an interface to analyse scans. I don't consider this high priority, but you might want to add it as an optional task if you still have time towards the end of GSoC.
1. Achieve autonomous scanning in Exitmap with periodic scans that,based on a certain algorithm, fetches relay descriptors and automates various subtasks for consistent data collection and verification. The main challenges that I expect will be intelligently recognizing which tasks to automate and when, and making the entire background process execution efficient in resource consumption.
This is the most important issue. A solid implementation of this would be very helpful.
2. Emulating multiple user interaction in individual modules and inExitmap overall to provide indistinguishability to Exitmap from regular users. I will try to explore libraries for this purpose like Splinter with Selenium or BeautifulSoup with Requests that help dynamically interaction with the web resource. The main challenges that I expect will be to scale this automated testing alongside the running asynchronous jobs and making the entire scans look like genuine user interactions. Any suggestions on better ways to do this will be helpful.
Yes, that would be great to have. At this point, we are mimicing Tor Browser, which doesn't work that well because the HTTP headers are stored in an orderless dictionary: https://github.com/NullHypothesis/exitmap/blob/master/src/util.py#L192
3. Making the codebase more robust by adding unit test cases. Iplan on using either the plain unittest/unittest2 framework or nose/nose2/pytest tools or any other alternatives that I may find or be recommended. I plan to simultaneously write the unit test cases for new code added and improve upon the exiting testing programs.
Sounds good. For what it's worth, py.test was added in commit 63671d3f.
4. (Optional) I read from the mail threads on the tor-dev mailinglist that the code needs to be converted to be Python3 compatible. Would like your opinion on whether it is a viable option and if it is possible, would like to include this in my list of tasks.
I haven't given it a shot myself, but I cannot think of a reason why it would be hard. (Famous last words!) I would add it to the list of optional tasks.
5. (Optional) If I can spare time in the milestone timeline and ifdiscussion leads to some clarity, I would like to add another module for more cleartext protocols that could be implemented like SNMP or Telnet. I am also looking at possible local to remote attacks that are active at the application layer and could be tested in Exitmap. I'll update if I find anything.
Sounds good.
Cheers, Philipp
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grarpamp -
Mridul Malpotra -
Philipp Winter