Questions tagged [protocol]

Tor has developed several internal protocols, like the rendezvous specification, directory specification etc. This tag is for questions which deal with protocols Tor uses.

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62
votes
1answer
27k views

How do onion addresses exactly work?

I understand that the .onion address is a public key of sorts, but not much more than that (I can vaguely guess, though). When nobody knows the IP of the .onion address, how do requests reach it? Are ...
42
votes
3answers
45k views

How does Tor route DNS requests?

Tor can only handle TCP connections, but DNS is a UDP protocol. How does Tor route DNS requests over its TCP based network? Why can the same approach not be used to route all UDP traffic over Tor?
21
votes
1answer
15k views

.onion Domains DNS lookup

How does Tor resolve .onion Domains? Are there also some central DNS servers in the Tor network that store these records? Is there a chance that two hidden services generate the same domain name?
20
votes
1answer
6k views

Is it possible to look up the public key for a .onion-address?

I know .onion addresses are a (partial) hash of a descriptor which contains a public RSA key, so I was wondering: it is possible to see the public key that is found when connecting to a .onion hidden ...
9
votes
1answer
1k views

Traffic secrecy in rendezvous points

In the Tor hidden service design Alice and Bob communicate via a rendezvous point that they agree to at one of the hidden service's introduction point. Can either of these nodes observe traffic ...
9
votes
1answer
4k views

RDP over Tor - safe?

I am considering using remote desktop protocol(RDP) over Tor, to circumvent my country's blockade of RDP and also get the most of anonymity. I just tested a RDP connection with proxy chains remmina. ...
9
votes
1answer
141 views

Does Tor take node age into consideration when building a circuit?

I've seen this for a while, but in my experience Tor seems to select well stablished nodes (whose uptime is >60 days) but in the specifications this is not shown. It's just that the current list of ...
9
votes
1answer
78 views

Can intermediary nodes learn the length of a circuit?

This should be impossible because of the layered encryption, but some documentation suggests that this can somehow be done. From Section 5.6 [1] of tor's specification When speaking v2 of the link ...
8
votes
2answers
2k views

Is there any Tor's network technical details paper?

I'm looking for technical details of tor's infrastructure. I did a little search but couldn't find anything special except https://www.torproject.org/about/overview.html.en which is not very in ...
7
votes
3answers
3k views

Where is the Tor API documentation?

I want to have a program I'm writing interact with the Internet exclusively through Tor. After perusing the Tor project's documentation it appears that they do not specify the API anywhere i.e. how a ...
7
votes
1answer
764 views

What are the minimum amount of nodes traffic passes through?

Is there a minimum amount of nodes traffic goes through before reaching it's destination? To my understanding of Tor, every node increases the effectiveness of the encrypted communication.
7
votes
1answer
2k views

How to force Tor to use just one circuit?

We use Stem's launch_tor_with_config with the following config and then close all circuits opened by it (with close_circuit). MaxCircuitDirtiness and NewCircuitPeriod: tens of hours ...
6
votes
2answers
1k views

What is the reasoning behind keeping hidden service onion RSA keys at 1024 length?

Is the cost to performance of using larger key length not cost effective? How would it negatively impact anyone if some hosts decided to use a larger key length (i.e. Why isn't anyone free to manually ...
6
votes
2answers
843 views

Are Tor Hidden Service Addresses private by default?

If I want to configure a Hidden Service but only for personal use and didn't give out its hostname/.onion address to anyone. Can its address still be crawled/known to any third party? Summary: If no ...
5
votes
1answer
100 views

Is Tor traffic using the TAP handshake vulnerable to retroactive decryption?

Assume an attacker with a record of Tor traffic between a client and guard has precomputed the 1024-bit Oakley group for Diffie-Hellman used in the TAP protocol. This would allow them to rapidly ...
4
votes
2answers
2k views

What happens with TCP connections on SIGNAL NEWNYM?

When I send the NEWNYM command tor will build new circuits. I'm wondering what happens with open TCP connections. Will tor wait a certain timeout to give them a chance to close, or do I break those ...
4
votes
1answer
294 views

What is the risk of guard relay and exit relay being one and the same?

Looking at the circuits build for a client during a Tor process, I have noticed the following: Four circuits were built. On the first circuit the guard node was a1. On the second circuit the exit ...
4
votes
1answer
703 views

Using Tor Proxy through other aplications

Before I proceed, I would like to mention that I understand that Tor browser integrates unique features such as not loading certain html canvases, scripts and a whole bunch of additions to make ...
4
votes
1answer
559 views

How does TOR extend circuit to a third node?

I am reading the Tor: The Second-Generation Onion Router article and my question is that how TOR extends circuit to a third node? On page 7 of the article,left column, it says: To extend the ...
4
votes
3answers
2k views

Can tor nodes (entry, exit, others) store IPs?

I'm a new Tor user. And I want to ensure several questions. Can "entry point" router store my IP? Can "middle relay" store "entry point" IP? Can "exit point" router store "middle relay" IP? I think ...
4
votes
1answer
404 views

Is all traffic using the file protocol (file://) for smb/samba shares routed through Tor using tor browser?

I need to connect anonymously to a remote samba server. This is possible using an url like: file:///ip.to.the.server/share in the Tor browser bundle - I've checked. My question is, can I be sure ...
3
votes
2answers
231 views

Can hidden services accept multiple simultanous connections?

When a webserver runs behind a hidden service, can it serve multiple HTTP requests at the same time, or will it only be able to handle one request at a time?
3
votes
2answers
2k views

WebSocket over Tor

I've been researching for many hours, but haven't found a definite answer. Is it possible for a client to connect to a hidden service with websocket? If so, how can I learn more? If not, is there an ...
3
votes
1answer
192 views

Which protocol has the better perfomance TAP or NTor

Just wondering, which protocol, TAP or NTor is less computationally intensive for a relay to process and why ? Thanks Rich
3
votes
1answer
1k views

How does it work - “Hidden services”?

Could somebody describe to me, like for Nooo-oo-ob, from the Start and to the complete End. My questions are: I've setup HS. My Tor client connect to the rendezvous. Is it populate full onion ...
3
votes
1answer
124 views

Can a relay decide which protocol to use (TAP or ntor)?

I've just started studying Tor and I came across TAP and ntor protocols. Just want to clear up that are these protocols decided at the time of circuit creation or each relay can decide on its own that ...
3
votes
1answer
72 views

Path selection constraints not working as expected

From Section 2.2 of the path specification We do not choose any router in the same family as another in the same path. (Two routers are in the same family if each one lists the other in ...
3
votes
1answer
324 views

Signal NEWNYM vs Stream isolation

Resources. This answer explains well what happens at NEWNYM request, and I also dig into the code, yet my lack of knowledge on low level networking prevents me to make a proper design decision if ...
2
votes
2answers
121 views

Does Tor add encryption at the TCP protocol level?

Just wondering if http://www.tcpcrypt.org/ would be useful to add? Also is there any work being done to replace/add encryption at the ODI level?
2
votes
3answers
1k views

How to change Tor exit node when using multiple SocksPorts?

I'm using Tor with multiple SocksPorts. Does anyone know how I can programmatically change the exit for each SocksPort separately? The code below changes the exit nodes for all the SocksPorts -- I ...
2
votes
1answer
47 views

How many descriptors can be retrieved in one request using the descriptor digest?

in the Tor dir-spec.txt I can see a note stating that due to squid proxy url limitations it is only possible to download 96 descriptors when using the fingerprints. Does this also apply to the ...
2
votes
1answer
268 views

How is Path Selection done in Tor?

Can anybody explain how path selection is done in Tor because the man page fail to specify in detail on how certain probabilities are calculated etc. In the man page there are a set of equations: ...
2
votes
1answer
70 views

What are the immutable characteristics that uniquely identify a relay?

In other words, what are the system "ingredients" that are not allowed to change without triggering attribution of a new fingerprint and the restart of the "ramp up" / flagging process? Please ...
2
votes
1answer
228 views

How does handshake with directory server work?

How does handshake with directory server work in the standard setup? How does it work when you configure Tor Browser to use a custom bridge?
2
votes
1answer
146 views

Is ADD_ONION control command implemented in the latest stable release?

control-spec.txt mentions an ADD_ONION command to create ephemeral hidden services. Does this exist in the latest stable release of Tor or Tor Browser Bundle?
2
votes
1answer
460 views

Allowing socks request for anonymous connections to a private address?

I want to ask you how I can allow socks request for anonymous connections. I'm using it with metasploit and socat but its always reject connection. So every time I want to exploit an OS with ...
2
votes
1answer
308 views

Usage and purpose of variable-length cells?

The Tor protocol version 1 uses 512-byte cells to obfuscate traffic patterns: Traffic flowing down the circuit is sent in fixed-size ``cells'', which are unwrapped by a symmetric key at each node ...
2
votes
1answer
29 views

What happens during circuit creation if one OR fails?

Hey just looking for some clarification on something. When creating a standard three hop circuit, if for some reason the client (Alice) does not receive a response from the third OR does she retry ...
2
votes
0answers
145 views

Detailed Understanding of Tor's connection establishment

I am really new to Onion Routing and Tor and I have just started reading about the topic on Wikipedia and the Tor Protocol Specification. Most of the concepts are explained very well but I have ...
2
votes
1answer
257 views

Can HORNET be implemented into Tor?

A while ago a group of researchers presented a Tor like network called HORNET; it is, reportedly, "a better, faster Tor". Do you know if the improvements proposed in the paper could be incrementally ...
2
votes
0answers
165 views

How do overlay network nodes communicate without IP addresses?

I've been reading about how Tor and I2P use cryptographic addresses to send messages to other nodes, but how does this work? I looked through the documentation for each and neither is very clear on ...
2
votes
0answers
22 views

Final relay able to encrypt data to the client? [duplicate]

Have been reading the one cell is enough to break anonymity paper, and just have a question. Once a circuit has been successfully created, can the final node of the circuit encrypt a piece of data ...
2
votes
0answers
113 views

What purpose does congestion control achieve, and how does it work?

I am trying to understand exactly how the different solutions for the congestion control mechanism work and what purpose they achieve. With "the solutions" I mean the circuit level throttling and the ...
1
vote
1answer
1k views

TOR and Obfsproxy packet size

I have some questions about TOR and Obfsproxy packet size. TOR cell size is 512 bytes but most TOR packets have size of 586 bytes. My question is that why there is such difference in size (74 bytes ...
1
vote
1answer
50 views

Clearing the state of rendezvous client provides privacy improvement?

Context. In my quest on figuring out if I must use NEWNYM signal or stream isolation is enough for me I dig into the code and narrowed down the possible privacy improvements that NEWNYM can bring over ...
1
vote
1answer
134 views

Tor router validation

my question is how does Tor validate routers? There are some specifications that mention that there are "validated" nodes, which have a "valid" flag (e.g. https://gitweb.torproject.org/torspec.git/...
1
vote
1answer
99 views

Add SocksPort using Tor Controller?

Can I add additional SOCKSPORT entries using Tor Controller? I looked through control-spec.txt and could only find examples of reading the current SOCKSPORT using GETCONF.
1
vote
1answer
665 views

How does tor find the nodes?

How does tor find the nodes? In other words, how does tor know which ip addresses are tor nodes and which aren't?
1
vote
1answer
33 views

Rekeying a Tor circuit

Is it possible to rekey a connection between a Tor client and a relay? By rekey I mean perform the usual x25519 key exchange to change the session key on the fly, without tearing the circuit down.
1
vote
1answer
152 views

Clearing the client side DNS cache provides privacy improvement?

Context. In my quest on figuring out if I must use NEWNYM signal or stream isolation is enough for me I dig into the code and narrowed down the possible privacy improvements that NEWNYM can bring over ...