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GTALUG logo  ↑  Tor logoGTALUG: Short Talks on Crypto

Tor, The Onion Router

Tuesday, 11 November 2014

at GTALUG: Greater Toronto Area Linux Users Group

by

Bob Jonkman of SOBAC Microcomputer Services

GTALUG logo  ↑  Tor logoAbout Bob Jonkman
Bob Jonkman and his Tin Foil Hat
  • System Administrator, Project Manager, Computer Course Instructor
  • Free Software enthusiast, Social Justice activist
  • Owner of SOBAC Microcomputer Services
  • Not a Mathematician, Cryptographer, Cryptologist, Cryptozoologist
GTALUG logo  ↑  Tor logoThe Problem we're trying to solve:

Being Anonymous on the Internet

  • Prevent your ISP / Employer / Library from knowing what Web sites you visit
  • Prevent the Web sites you visit from knowing your origin
GTALUG logo  ↑  Tor logoNot the Problem we're trying to solve:
  • Keeping your data transmission secure (TLS data encryption)
  • Keeping your data storage secure (File and Disk encryption)
  • Proving your identity (N-factor authentication)
  • Verifying the Web site (Certificates)

Maybe the problem we're trying to solve:

  • Maintaining your personal privacy (identity spoofing, anti-surveillance legislation)
GTALUG logo  ↑  Tor logoTarget audience for this presentation
  • Regular folks who want to preserve their privacy and anonymity

Not the target audience for this presentation:

  • Web site operators who need Hidden Services
  • Exit Node Operators
  • People providing Privacy/Anonymity services to others
GTALUG logo  ↑  Tor logoTor is The Onion Router

How it works:

Step 1: Alice's Tor client obtains a list of Tor nodes from a directory server

From Tor Project: Overview by the Tor Project, used under a CC BYCC BY 3.0 license

GTALUG logo  ↑  Tor logoTor is The Onion Router

How it works:

Step 2: Alice's Tor client picks a random path to destination server. Green links are encrypted, red links are in the clear

From Tor Project: Overview by the Tor Project, used under a CC BYCC BY 3.0 license

GTALUG logo  ↑  Tor logoTor is The Onion Router

How it works:

Step 3: If at a later time Alice visits another site, the Tor client selects a second random path. Again, green links are encrypted, red links are in the clear

From Tor Project: Overview by the Tor Project, used under a CC BYCC BY 3.0 license

GTALUG logo  ↑  Tor logoBest Practices

Boot a clean, uncompromised computer

  • An unknown computer already turned on may be running code to circumvent Tor
  • Use Portable Tor or TOAST on computers you don't own
  • Even better, use the portable operating system Tails on computers you don't own
GTALUG logo  ↑  Tor logoBest Practices

Browse only encrypted Web sites with https://

  • Compromised exit nodes can see all unencrypted traffic
  • Check certificates to make sure the SSL Certificate Authority is correct
GTALUG logo  ↑  Tor logoBest Practices
No Tor, No HTTPS
No Tor, no HTTPS

From Tor and HTTPS by the Electronic Frontier Foundation, used under a CC BYCC BY 3.0 license

GTALUG logo  ↑  Tor logoBest Practices
No Tor, HTTPS
No Tor, no HTTPS

From Tor and HTTPS by the Electronic Frontier Foundation, used under a CC BYCC BY 3.0 license

GTALUG logo  ↑  Tor logoBest Practices
Tor, No HTTPS
No Tor, no HTTPS

From Tor and HTTPS by the Electronic Frontier Foundation, used under a CC BYCC BY 3.0 license

GTALUG logo  ↑  Tor logoBest Practices
Tor, HTTPS
No Tor, no HTTPS

From Tor and HTTPS by the Electronic Frontier Foundation, used under a CC BYCC BY 3.0 license

GTALUG logo  ↑  Tor logoBest Practices

Use the Tor Browser Bundle

  • Tor Browser is an Extended Support Release of Firefox (24.8.1esr), especially hardened against data leakage
  • Tor Browser has specific Add-ons NoScript and HTTPS Everywhere to provide additional protection
GTALUG logo  ↑  Tor logoBest Practices

Use only the software supplied with the Tor Browser Bundle

  • Other Add-ons may be compromised to circumvent Tor
  • Add-ons are written for an environment not designed for secure computing: XSS and XSRF
  • Applications leak data (Ad tracking, DNS requests, OS calls)
GTALUG logo  ↑  Tor logoBest Practices

Don't use Bittorrent

  • Bittorrent enables peer-to-peer filesharing; P2P is the opposite of Onion Routing — your IP address is in every Bittorrent packet, tracker, Distributed Hash Table
  • Bittorrent has far greater bandwidth requirements than the Tor network can deliver
GTALUG logo  ↑  Tor logoOther Considerations
  • Tor can be slow and laggy; browsing is painful, video and conferencing almost impossible
  • Many sites ban traffic from Tor Exit Nodes
  • Using Tor may harm your reputation
GTALUG logo  ↑  Tor logoLegal Considerations

IANAL

I Am Not A Lawyer

  • Don't do illegal things!
  • Merely using Tor will cast suspicion on your behaviour
  • If you've done nothing wrong you have nothing to fear
  • Corollary: What are you hiding if you're not doing anything wrong?
  • Running a Tor Exit Node may allow others to use your computer to do illegal things
GTALUG logo  ↑  Tor logoTor Failure Modes
GTALUG logo  ↑  Tor logoTor Downloads
  • Official site: The Tor Project
  • Software available for:
    • Linux (32 bit)
    • Linux (64 bit)
    • Android: Orbot
    • Windows (32 bit)
    • Mac OSX (32 bit)
GTALUG logo  ↑  Tor logoTor, The Onion Router

Bob Jonkman

Unless otherwise noted, all material is Copyright © 2014 by Bob Jonkman and SOBAC Microcomputer Services, and released under a CC BYCC BY 4.0 license

GTALUG logo  ↑  Tor logoDemonstration

Insert scary demonstration here

  • If time and the demo daemons permit, demonstrate packet captures off the WiFi with and without Tor enabled