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Tor: Browsing anonymously with onion routing

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tagsglossar, security, datenschutz

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Tor: Browsing anonymously with onion routing

In short: A network that routes traffic through several encrypted intermediate stations so that neither the website nor eavesdroppers can tell who is visiting what.

In more detail: Tor (The Onion Router) prevents any single party from knowing both who you are and what you are visiting. The Tor Browser connects you through three nodes (relays) run by volunteers. Each layer of encryption is removed by only one node, like peeling an onion.

In Depth

The path through three nodes

  1. Entry node (guard): knows your IP address but not the destination.
  2. Middle node: knows neither you nor the destination.
  3. Exit node: knows the destination (and with unencrypted traffic the content) but not you. Your computer encrypts the data three times (one layer per node). Each node removes its layer and passes the rest on. The route changes regularly.

Onion services

Websites ending in .onion are reachable only through Tor. Here the provider also stays hidden, and traffic never leaves the Tor network. Examples are news sites, whistleblower platforms and services in countries with censorship.

Benefits and limits

Tor protects against observation of your location by websites, providers and local networks and helps against censorship. It makes things slower because traffic takes detours. Anonymity is not absolute: whoever signs in to a site with their account reveals themselves; browser fingerprint, scripts and your own mistakes (for example opening files outside Tor) can unmask you. Against attackers who observe entry and exit there are theoretical correlation attacks. The exit node sees unencrypted traffic, so use HTTPS.

Using Tor is legal in Germany. It is used by journalists, activists and private persons, but also misused for crimes. The Tor Browser (Firefox-based) comes preconfigured and should be used unchanged, without extra extensions and at the default window size. A VPN is something different: it shifts trust to one provider.

See also: VPN, TLS, Data protection in everyday life