NoteThis here is going to be another longer article, where things might get a bit technically… bumpy. I’ll try to explain it as simply as possible.
What does a Tor Relay do on ChristiansBlog?
Those who are currently browsing the left side of this website will find a small, somewhat unusual entry there:
🧅 Tor Relay · 🟢 Online
No, this is not a poorly hidden VPN ad link and also not an attempt to send anyone to the dark corners of the internet. 😄
I operate my own Tor Relay.
And because I consider transparency in technical matters quite important, you can also see on this website whether it is currently running.
What is Tor actually?
Tor stands for The Onion Router and is a network that routes connections through multiple stations so that no single place knows both who initiated a connection and where it ultimately goes.
The principle can be simplified as follows:
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Each station takes over only a part of the task. A Tor circuit typically consists of several relays; Guard and Middle are not Exit relays.
This is one of the key differences to a classical VPN:
With a VPN, traffic generally runs through a provider you have to trust. With Tor, the connection is instead routed through a distributed network of various relays.
Tor is therefore not a magical invisibility button. Tor also cannot prevent you from, for example, identifying yourself through personal access credentials or making other mistakes.
And what is a Tor Relay exactly?
A Relay is a computer that provides part of the Tor infrastructure.
Tor does not function by having a single large server where “the Tor internet” runs.
The network consists of thousands of relays provided by different operators. Tor Metrics describes the network accordingly as one with thousands of voluntarily operated relays and millions of users.
A Relay receives encrypted Tor traffic and forwards it within the Tor network.
There are different roles.
Guard Relay
The Guard Relay is usually the first node of a Tor circuit.
Middle Relay
The Middle Relay forms an additional station within the circuit.
Exit Relay
The Exit Relay is the station through which a connection leaves the Tor network and reaches the regular internet.
My Relay is not an Exit Relay.
That is an important distinction.
I am therefore not simply providing a server whose IP address then appears as the starting point for any Tor connections on the internet.
Why do I operate a Relay at all?
The short answer is:
Because a decentralized network needs people who provide the infrastructure.
This is actually not that different from many other things we use on the internet without thinking.
Who operates their own mail server, provides a DNS server, hosts a Linux mirror, or operates a Tor node, provides infrastructure for others.
However, Tor adds something crucial:
For some people, a free internet is not a given
While we in Germany can usually assume that we can reach almost any website and internet service, the situation in other countries can be completely different. And yes, I know that access to some sites, especially those that work with disinformation, is blocked from Germany.
In countries with extensive internet censorship, governments or internet providers can specifically block access to certain websites, services, or even the Tor network itself.
This affects people in countries like China or Iran, but also other regions where internet access is monitored, filtered, or restricted.
Tor is therefore not just a tool for people who want to protect their privacy.
For people in censored networks, Tor can be a tool to get access to information that is otherwise withheld from them.
The Tor Project explicitly points out that direct connections to the Tor network can be blocked by internet providers or state authorities in some countries. Additional techniques for circumventing censorship are available precisely for such situations.
Is Tor really safe?
At this point, there is also an uncomfortable truth to mention:
Tor is not a magical anonymity cloak.
The Tor network is intentionally open. Basically, anyone can operate a relay. This is one of the great strengths because it creates a worldwide, decentralized network.
On the other hand, it also means:
Not every relay has to be trustworthy automatically.
The Tor Project is very aware of this problem. There are always relays that are misconfigured or operated by operators with malicious intentions. The Tor Project therefore monitors the network for unusual behavior and can have problematic relays removed from the network by the Directory Authorities. In the past, larger groups of malicious relays have already been discovered and removed.
Can there also be state actors among them?
Theoretically: Yes.
A Tor Relay is, first and foremost, a server. There is no technical mechanism that prevents a secret service, a police authority, or another state actor from operating their own relay.
Whether a specific relay is actually operated by a government or a intelligence agency cannot be determined solely based on the public relay data.
Therefore, one should approach statements such as „X percent of all Tor relays belong to the CIA“ or similar claims with great caution. Such numbers are not publicly verifiable.
What is verifiable, however:
Malicious relay groups have already existed.
The Tor Project, for example, has in the past identified large relay groups that were classified as potentially malicious and subsequently removed from the network.
Attacks via exit relays are also not a theoretical possibility. The Tor Project has, for example, discovered groups of exit relays that attempted to manipulate unencrypted HTTP traffic. In a documented case, so-called SSL stripping was used to prevent users from automatically switching to HTTPS. The affected relays were then removed from the network.
What does this mean for the security of Tor?
Here it gets interesting.
Tor does not attempt to solve the problem by simply trusting every relay.
The opposite is true.
Tor is built on the principle that one does not need to fully trust individual relays.
A typical Tor circuit consists of several relays:
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The guard relay knows your access to the Tor network but does not know your final destination.
The exit relay knows the destination of the connection but usually does not know your original IP address.
The middle relay connects these two sides together without knowing the entire connection.
This distributes the necessary trust across several independent stations.
But what happens if an attacker controls multiple relays?
Then it really becomes interesting.
If an attacker can observe both the entry and exit points of the Tor network, they can attempt to correlate data streams based on timing, data volume, and other traffic patterns.
This is called a traffic correlation or timing attack.
And here, Tor is very clear:
Tor cannot reliably prevent an attacker from correlating traffic if they can observe both ends of the connection.
Exactly for this reason, Tor uses so-called entry guards. A Tor client does not use a completely new entry point for every connection, but rather a small group of guard relays. This reduces the probability that an attacker randomly controls or observes exactly the entry point.
Is Tor therefore insecure?
No. But Tor has a defined threat model.
Tor is very effective against many forms of surveillance:
- Your internet provider usually does not see which specific website you are visiting via Tor.
- The target website does not see your normal IP address.
- A single relay can usually not simultaneously see your identity and your destination.
- The distribution across multiple independent relays significantly complicates simple surveillance.
Against a very powerful adversary who can observe large parts of the internet and also monitor both the entry and exit of a connection, Tor cannot guarantee perfect anonymity.
This is not a weakness that can simply be eliminated by adding another checkmark in the settings.
It is a fundamental limitation of so-called low-latency anonymity networks. The Tor Project explicitly describes this limitation itself.
And what does this mean for me as a relay operator?
My own relay is therefore also not a place where I can see who is using Tor and which websites these people are visiting.
On the contrary: The Tor Project explicitly urges relay operators not to analyze or alter network traffic and not to disclose user or destination IP addresses or detailed timing and volume information.
My relay is a small part of the network.
It is neither a surveillance server nor an access point to any personal data of Tor users.
And precisely in this lies an important part of the concept:
A Tor relay does not need to be trustworthy for the overall system to function.
The more independent the individual relays are from each other, the better the distribution of trust.
What should Tor users still be aware of?
Tor should therefore not be translated as „I am now completely invisible."
A few basic rules remain important:
- Use the Tor Browser if you want to browse anonymously.
- Keep the browser up to date.
- Do not voluntarily reveal your identity, for example by logging in with a personal account.
- Pay attention to HTTPS.
- Do not install additional browser extensions that could impair fingerprinting protection mechanisms.
- Do not assume that Tor automatically protects other programs on your computer.
- Be aware that a powerful adversary with extensive surveillance capabilities can fundamentally analyze Tor traffic.
The correct statement is therefore not:
„Tor makes you anonymous.“
But rather:
„Tor significantly hinders linking your identity with your internet traffic.“
And that is a big difference.
And here come the bridges into play
A normal Tor relay is publicly known. Its existence and certain technical information can be retrieved via Tor Metrics.
This is necessary for the functioning of the normal Tor network.
For a censor, however, this means:
If I know which IP addresses belong to Tor, I can try to block those IP addresses.
Exactly for this reason, Tor bridges exist.
A bridge is essentially a Tor relay as well, but it is not listed in the public Tor directory. This makes it significantly more difficult for internet providers or government agencies to identify and block all bridges.
Simplified, it looks like this:
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This allows someone whose internet access is directly blocked by Tor to still find a way into the Tor network.
Tor is not just trying to “sit out” censorship
Bridges are only part of the system.
Tor uses so-called Pluggable Transports to make the connection harder for censors to detect.
These include among others:
- obfs4
- WebTunnel
- Snowflake
- meek
These techniques pursue different approaches.
obfs4 makes Tor traffic appear like random data, making it harder for censors to find bridges by automatically scanning.
WebTunnel tries to make a Tor connection appear like normal HTTPS web traffic.
Snowflake uses voluntarily provided proxies, so the connection appears to an outsider more like a regular real-time communication.
meek uses yet another approach and makes the data traffic appear as if the user is accessing a large website or a CDN service.
This is quite an impressive cat-and-mouse game between censorship and its circumvention.
Why this is important
Imagine living in a country where certain news portals are blocked.
Or social networks are only partially accessible.
Or websites of human rights organizations are blocked.
Or the government decides during a political crisis to restrict access to large parts of the internet.
Then the question is no longer:
“Do I want to improve my privacy?”
But possibly:
“Can I even still access independent information?”
Exactly here, a decentralized network like Tor gains a significance that goes far beyond anonymous browsing.
It is about freedom of information.
About freedom of speech.
About access to independent information.
And ultimately also about the fact that no single government or single internet provider should be able to decide which information a person is allowed to see.
The Tor Project describes its mission not only with privacy and anonymity, but explicitly also with protection against censorship and support for the free availability of such technologies.
And that’s exactly why Tor needs people who provide the infrastructure
The network does not function on its own.
Relays must be operated by people and organizations.
Bridges must be provided by people.
And also the various tools for circumventing censorship need an infrastructure that is supported by volunteers and other operators.
The more independent operators participate, the harder it becomes to fully control or shut down such a network.
That is why I operate a relay.
Not because I want to sell something to someone.
Not because I want to derive any special status from it.
But because I believe:
If we want a free and decentralized internet, we must also be willing to provide a small part of the necessary infrastructure ourselves.
My relay is just a very small piece of the puzzle.
But exactly from many such small pieces, a network emerges that is not controlled by a single company, a single government, or a single operator.
And that’s why there is this in my sidebar:
🧅 Tor Relay · 🟢 Online
A small point on a website.
But behind it lies a quite significant principle.
A free internet only works if people are willing to carry a piece of it.
And why is the status on my website?
Because I find it interesting.
And because I prefer to show what is actually happening in technical projects rather than just writing “running” somewhere. 😉
The small status in the sidebar shows the current state of my own relay.
It does not involve directly querying any Tor service from the browser every time.
The website uses a local JSON file:
/data/tor-relay.json
A server-side process regularly queries the official Tor Onionoo API and updates these data.
Onionoo is exactly for that purpose: it provides information about running Tor relays and bridges as JSON, which can then be used by applications and websites.
Simplified:
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The browser does not have to communicate directly with Onionoo.
What can you see about my relay?
Clicking on the small status leads to Tor Metrics and allows you to view the public information about my relay.
There, information such as
- Relay name
- Fingerprint
- Status
- IP addresses
- Country
- Tor version
- Relay flags
- Time of first sighting
- Last sighting
- Restart time
- Bandwidth
- Consensus Weight
is provided.
My relay is found there under its unique fingerprint.
Relay Search:
https://metrics.torproject.org/rs.html#details/93EE8F121C175DD3B77E586F78E789E711491955
What does “Online” actually mean?
The green dot does not mean:
“Christian is sitting next to it and watching the Tor server at work.” 😄
The status comes from the data of the Tor network.
Tor Metrics or Onionoo processes the network status data published by the Directory Authorities. The field running indicates whether the relay was listed as running in the last network status consensus.
Therefore, the status is not necessarily a millisecond-accurate live measurement.
He is rather the answer to the question:
“Is this Relay currently being operated as a running relay in the Tor Network?”
And what does this have to do with this blog?
Actually a lot.
This blog has been dealing with technology, Linux, privacy, digital self-determination, and the things that happen behind the scenes on the internet for years.
A personal Tor Relay fits quite well into this.
I find it more meaningful to not only talk about decentralized infrastructure, but also to provide a small part of it myself. Whether as a Matrix Server for my own digital communication, or as a Tor Relay here.
And that’s exactly why there’s now this small point:
🧅 Tor Relay · 🟢 Online
Not as advertising.
Not as a status symbol.
But simply as a small public piece of information:
This website is operated by someone who doesn’t just write about free and decentralized infrastructure, but also provides a small part of it themselves.
How can I use Tor myself?
Now, perhaps the most important question:
How do you actually use Tor?
The good news: You don’t need to run your own Tor server or deal with Linux, networking technology, or any complicated configurations.
For most people, the simplest entry point is the Tor Browser.
The Tor Browser is based on Firefox and is already set up so that all browser traffic is routed through the Tor network.
Install Tor Browser
You should only download the Tor Browser from the official website of the Tor Project:
https://www.torproject.org/download/
There you can find versions for:
- Windows
- macOS
- Linux
- Android
There is no official Tor Browser for iPhone and iPad due to technical limitations set by Apple. The Tor Project points to other options or compatible applications there.
After installation, start the Tor Browser and connect to the Tor network.
After that, the data traffic of the Tor Browser runs through Tor.
An important detail is:
Tor protects the traffic of applications that actually run through Tor.
If I use the Tor Browser, that doesn’t automatically mean that all other programs on my computer also communicate through Tor.
My normal Firefox window, Steam, Thunderbird, or any other application won’t automatically switch to a Tor connection.
And how does it work when browsing?
If I, for example, visit a website with the Tor Browser, the connection isn’t simply established directly:
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Instead, it is routed through several stations of the Tor network:
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The individual stations only know the part of the connection necessary for their task.
The goal is that no single Relay operator knows:
“This person has just visited this website.”
Tor is not a free pass
And here comes a point that is especially important to me:
Tor does not automatically make anyone anonymous.
If someone logs in with their normal Google, Facebook, or Amazon account, they have identified themselves with that service.
Personal information, browser behavior, or other mistakes can also lead to the identification of the user.
The Tor Browser therefore tries to reduce as many possibilities for identification and tracking as possible.
Nevertheless, it remains true that:
Tor is a tool for privacy and circumventing censorship – not a guarantee for absolute anonymity.
What about countries where Tor is blocked?
Here it gets interesting again.
In countries with strong internet censorship, a direct connection to the Tor network can be blocked.
Sometimes it’s not enough to simply install the Tor Browser and click “Connect.”
The Tor Browser therefore offers options for circumventing censorship.
These include bridges and various so-called pluggable transports.
Bridges are not publicly listed Tor Relays. This makes them harder to block based on the public Tor Relay list.
Pluggable transports try to further change or hide the Tor traffic so that it’s harder for censorship systems to recognize it as Tor traffic.
This can make a significant difference for people living in censored networks.
Do I have to use the Tor Browser?
No.
Tor can generally also be used by other applications.
For normal users, the Tor Browser is however the simplest and safest entry point, because many important settings for using Tor are already prepared.
Those with more advanced requirements can use Tor through a local SOCKS proxy or other suitable applications.
That’s more for technically savvy users.
For the beginning, it’s therefore:
Download, install, and start the Tor Browser – done.
And if I want to not only use, but also support Tor?
Then there are various options.
Run a Tor Relay
Exactly what I’m doing.
By doing so, you provide a server as part of the Tor infrastructure and forward Tor traffic for other users.
Run a Bridge
Bridges are especially interesting if you want to help people in censored networks gain access to the Tor network.
Support Snowflake
You can also support the Tor Project without running your own server.
At Snowflake, normal users can offer part of their internet connection as a proxy for people in censored networks.
You don’t have to know yourself who uses the proxy or which websites are accessed through it.
More information and options for support can be found directly at the Tor Project:
https://community.torproject.org/relay/
And so we’re back to the small green dot
If you see during your next visit to this website, on the left side in the sidebar
🧅 Tor Relay · 🟢 Online
you now know what it means behind.
It’s not a VPN offer.
No commercial service.
And also not an attempt to promote any secret corners of the Internet.
It’s simply a small computer that provides part of its resources so that a decentralized network can function.
And just like with open-source software, it also applies here:
Many small contributions can together create something quite big.
But … um … HÄ?
Who is now wondering how the whole thing is supposed to work if the individual points only know part of the journey, it probably feels exactly the same as me during my first attempt to understand. 😄
So let’s do it very slowly.
Let’s start with the normal Internet
You are sitting in front of your computer and enter in the browser, for example:
What happens?
In simplified terms, the path looks like this:
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Your computer knows where it wants to go.
Your internet provider knows from which connection the request comes and can generally see to which destination the connection is being established.
And the webserver of ChristiansBlog receives the connection from your public IP address or from the address through which your connection appears in the Internet.
There is therefore a relatively direct connection:
DU ────────────────► CHRISTIANSBLOG.EU
And now we do the same with Tor
Now you want again:
to call up.
This time you are using the Tor Browser.
Your Tor client builds a circuit through several Tor relays first:
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And now comes the trick.
Imagine you want to send a letter.
You obviously know the recipient.
So you write:
„This letter should go to ChristiansBlog.“
But you don’t just give it to a single messenger.
Instead, you put the letter into several envelopes.
Each envelope contains only the information that the respective messenger needs for his part of the journey.
Simplified, it looks like this:
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You know from the beginning:
„I want to go to ChristiansBlog.“
But the messengers only get the part of the information they need.
Messenger 1 – the Guard
Messenger 1 gets the outer envelope.
He knows:
„This envelope comes from Christian.“
And he knows:
„I should pass it on to Messenger 2.“
What he doesn’t know:
„Christian wants to go to christiansblog.eu.“
Because this information is still in the inner envelopes.
Messenger 2 – the Middle Relay
Messenger 2 gets the envelope from Messenger 1.
He knows:
„The envelope comes from Messenger 1.“
And he knows:
„I should pass it on to Messenger 3.“
But Messenger 2 doesn’t know:
„Who is the original sender?“
or:
„Where should the journey end?“
He only knows his small part of the journey.
Messenger 3 – the Exit Node
Now comes the third messenger.
He gets the envelope from Messenger 2.
He knows:
„This envelope comes from Messenger 2.“
And now he can read the last information intended for him:
„Please bring this letter to christiansblog.eu.“
The Exit therefore knows where the connection should go.
But he doesn’t know that the letter originally came from your computer.
For the webserver, the connection therefore looks simplified like this:
Exit Relay ─────────► christiansblog.eu
and not like this:
Dein Rechner ─────────► christiansblog.eu
And that’s exactly where the trick is
If we now compare the information side by side:
Participant Knows the original sender? Knows the final destination?
| Participant | Knows the original sender? | Knows the final destination? |
|---|---|---|
| You | Yes | Yes |
| Guard Relay | Yes | No |
| Middle Relay | No | No |
| Exit Relay | No | Yes |
| Destination Server | No | Yes, of course |
That is the crucial point.
It’s not about Tor that no one knows where you want to go.
You know it.
And the Exit must ultimately also know it, otherwise it couldn’t establish the connection.
The trick is that no one on the way knows at the same time who you are and where you want to go.
The knowledge is distributed among several stations.
And that’s exactly why the whole thing works.
And the letter envelopes?
The letter envelopes are of course just an image.
In reality, the information is not sent with paper envelopes, but is protected by several cryptographic encryption layers.
Each relay can only process the layer that is intended for its part of the journey.
That’s why the name is:
Onion Routing – Onion Routing.
Like an onion, there are several layers.
Only that we should probably not start peeling off the individual layers at Tor. 😄
Sources
- Tor Metrics – Onionoo API – technical documentation of the API and its relay data.
- Tor Metrics – About – information about Tor Metrics and the data sources used.
- Tor Metrics – Overview – statistics and information about the public Tor network.
