home

= ** T **he ** O **nion ** R **outer (anonymity network) = (Change, Delete, Read.... Do as you wish. Just wanted to get something on here. tired of looking at the default. Just some relevant stuff I thought could be incorporated.)David

Tor
Overview

"Tor’s system architecture attempts to provide a high degree of anonymity and strict performance standards simultaneously [1]. At present, Tor provides an anonymity layer for TCP by carefully constructing a three-hop path (by de- fault), or circuit, through the network of Tor routers using a layered encryption strategy similar to onion routing [8]. Routing information is distributed by a set of authoritative directory servers. In general, all of a particular client’s TCP connections are tunneled through a single circuit, which rotates over time. There are typically three hops in a circuit; the first node in the circuit is known as the entrance Tor router, the middle node is called the middle Tor router, and the final hop in the circuit is referred to as the exit Tor router. It is important to note that only the entrance router can directly observe the originator of a particular request through the Tor network. Also, only the exit node can directly examine the decrypted payload and learn the final destination server. It is infeasible for a single Tor router to infer the identities of both the initiating client and the destination server. To achieve its low-latency objective, Tor does not explicitly re-order or delay packets within the network."([|TorSource])

Topology
[|(Quick view TorDesign])

"Tor also implements something called "leaky-pipe circuit topology". In the original Onion Routing protocol, only the last router in a route can act as the exit funnel. Tor changes the concept slightly, allowing any router along the route to be an exit funnel. This means that an attacker observing the end of a circuit will have a harder time figuring out where the traffic goes."([|Topology])

//Originating Services//
"Users of a Tor network run an onion proxy on their machine"

//Hidden Services//
"Tor can also provide anonymity to servers in the form of location-hidden services, which are Tor clients or relays running specially configured server software."

Strengths
as noted

Weaknesses
as noted

//Network Boundaries//
"Like all current [|low latency] [|anonymity networks], Tor cannot and does not attempt to protect against monitoring of traffic at the boundaries of the Tor network, i.e., the traffic entering and exiting the network."

//P2P Applications//
" the few clients that do use the network for P2P applications such as BitTorrent consume a significant amount of bandwidth. The designers of the network consider P2P traffic harmful, not for ethical or legal reasons, but simply because it makes the network less useful to those for whom it was designed." ([|TorSource])

//Insecure Protocols//
"Another surprising observation from the protocol statistics is that insecure pro- tocols, or those that transmit login credentials in plain-text, are fairly common. While comprising a relatively low percentage of the total exit traffic observed, protocols such as POP, IMAP, Telnet, and FTP are particularly dangerous due to the ease at which an eavesdropping exit router can capture identifying in- formation (i.e., user names and passwords). Tor multiplexes several TCP connec- tions over the same circuit. Having observed identifying information, a malicious exit router can trace all traffic on the same circuit back to the client whose iden- tifying information had been observed on that circuit. For instance, suppose that a client initiates both an SSL connection and an AIM connection at the same time. Since both connections use the same circuit (and consequently exit at the same router), the SSL connection can be easily associated with the client’s iden- tity leaked by the AIM protocol. Thus, tunneling insecure protocols over Tor presents a significant risk to the initiating client’s anonymity. To address this threat, a reasonable countermeasure is for Tor to explicitly block protocols such as POP, IMAP, Telnet, and FTP7 using a simple port- based blocking strategy at the client’s local socks proxy.8 In response to these observations, Tor now supports two configuration options to (1) warn the user about the dangers of using Telnet, POP2/3, and IMAP over Tor, and (2) block these insecure protocols using a port-based strategy [11]. However, this same type of information leakage is certainly possible over HTTP, for instance, so additional effort must also be focused on enhancing Tor’s HTTP proxy to mitigate the amount of sensitive information that can be exchanged over insecure HTTP. For instance, a rule-based system could be designed to filter common websites with insecure logins. Finally, protocols that commonly leak identifying information should not be multiplexed over the same circuit with other non-identifying traffic. For exam- ple, HTTP and instant messaging protocols should use separate and dedicated circuits so that any identifying information disclosed through these protocols is not linked with other circuits transporting more secure protocols." ([|TorSource])

Implementation
as noted

Need Help?

 * for immediate assistance with the website Dial 911 . An operator will assist you with any questions you have, and will deploy a response team for your needs.
 * media type="custom" key="11274034"
 * media type="custom" key="11273906"

=Sources (מקורות)= תודה על הביקורבאתר האינטרנט שלנו. אנא בקרושוב. אל תהססלערוך את הדףעםהמידע הרלוונטי. =media type="custom" key="11274410"=

A. //Overview//
 * A brief analysis of how the chosen technology works, its stage of commercialization/technical development, standards (or competing standards)
 * A brief discussion of it interoperates with the Internet and/or other types of networks
 * Key domains of envisioned applications (a minimal set of non-overlapping domains should be developed)
 * Key technical challenges that are currently faced by this technology (think of our Teledesic discussion to guide your thinking). Also consider network security and privacy issues here, if relevant.
 * Key business challenges that are currently faced by this technology. Is this technology creating an entirely new market or disrupting an existing market? Directly consider what/who this might be competing against (e.g., Skype disrupts ATT’s markets but iTunes creates a //relatively// untapped/new market). What management problems do you expect

B. A //competitive viability assessment// of the technology. You might find Porter’s 5-forces model to be a useful framework.
 * Application architectures that are appropriate and ones that are being attempted in the industry right now (think of Chapter 2 to guide your thinking)
 * Complementary technologies that are necessary for this to have its envisioned impact (e.g., VoIP needs broadband). Think of the necessary backbone networks and LAN/WAN networks, if applicable. You might also find the BPL class discussion to be a useful framework to guide your thinking.
 * Bargaining power asymmetry/market structure.
 * Potential entrants/entry barriers in the envisioned marketspace
 * Threat of substitute products/technologies (e.g., WiFi/WiMax for XM)

C. //Projected adoption// in the marketplace and the key elements in A and B above must come together for this to happen. Select a timeline from 2008-2013 and consider the best and worst case scenarios. Also consider this from a real options perspective (e.g., can your chosen technology be deployed for another purpose, and other types of embedded real options). Specifically think of the types of companies/individuals who could/would play into this analysis (think of specific companies to articulate your thinking).

D. Summary of critical success factors. (Specifically think about the staging options idea how this might affect your CSFs; remember how Teledesic and Wal-mart/RFID follow a big bang approach instead of a step-by-step approach).

E. Projections/predictions based on your analysis above. Think of this as your core conclusions.

F. Resources: All of your references should be hyperlinked from this page. This page should also serve as THE definitive set of online resources for exploring your topic in further depth.

// side notes from barrett for info

Tor operates using ﬁxed 512 byte cells (or packets) for

stronger anonymity and the Transport Layer Security (TLS)

protocol for authentication and privacy

When a message arrives at the ﬁrst OR on a circuit, the outer

layer of encryption is removed and the message is forwarded

to the next OR. This process is repeated until it reaches the

ﬁnal OR on the circuit. At this point, the message is decrypted

(revealing clear text) and forwarded to the destination address.

Layered encryption is a common technique used in anonymous

communication systems, however, to achieve low-latency

various other techniques that strengthen anonymity are omitted.

Mixing is one such feature.

Terrorist organizations can also make good use of the Tor

network. Tor could serve as a conduit to Internet communication

channels known to be used by terrorist organizations like web

pages and web-based email. Furthermore, Tor can be used to

research targets and weapons construction techniques without

fear of being located or identiﬁed. Finally, Tor’s hidden

services, intended to aid in countering government censorship,

can be used as a digital drop box where terrorist leaders can

secretly execute command and control.

Tor is vulnerable to a number of attacks aimed at both

denying service and degrading anonymity. DDoS attacks

targeting an OR’s CPU are possible due to Tor’s dependence on

TLS. Such attacks force an OR to execute so many public key

decryptions that it can no longer route message

Organize these resources in 4-6 key categories as you deem logical.