Questions tagged [dos]

Denial-of-service attacks are attempts to make machines or other network resources unavailable to their intended users.

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Disproportionate CPU usage

My new Raspberry Pi 3 relay was relaying 2 MBps using maybe 80% CPU for a few days. But suddenly, just today, it jumped to using 380% CPU, using almost all of each of the 4 cores to serve the same ...
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3 answers
190 views

Is denial of service possible by getting the exit node to create another circuit?

Even though circuit length is limited to 8, can an attacker create a circuit of length 8, and then get the exit node to create another circuit of length 8 (get the exit node to be a Tor client)? Then ...
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1 answer
214 views

Had valet nodes been implemented?

I am reading this article: https://blog.torproject.org/blog/hidden-services-need-some-love And there is a paragraph states that: Defense against Denial of Service of Introduction Points The ...
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2 answers
221 views

Are there problems on tor netowrk?

I have speed problems on tor with tails. I mean the browsing is very very slow. For example my usual bandwidth is 5,3 mbit and on tor network is 88 kbit. Some guy on #tor@oftc.net are saying that ...
2 votes
1 answer
96 views

Will the network know if a malicious guard keeps dropping connections?

Selective denial of service on guard nodes is a well-known attack, in which the malicious guard keeps dropping connections from Tor clients who are not in the set of his targeted victims. Do Tor ...
2 votes
2 answers
806 views

Are low bandwidth DoS attacks performed over the Tor network a problem to be considered?

For low bandwidth and slow DoS / DDoS attacks (for example Slowloris, SlowLoris and PyLoris) the Tor network seems to be very useful medium. For free it offers two important things to the attacker: ...
1 vote
0 answers
192 views

How does selecting new guard relays work?

I've been told guards are selected when a client first connects to the Tor network and used until they disappear. What constitutes disappearing? Do all guards need to disappear (and then the whole ...
3 votes
0 answers
408 views

How to mitigate layer 7 attacks on hidden services?

I've observed the following: The Tor client establishes reverse connections to random relays and any further hidden service traffic is tunneled trough these connections. This means: There are no ...
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1 answer
233 views

Can a tor hidden service be successfully attacked via (D)DoS?

I'm planning on creating a tor hidden service(in the context of a research project) and am wondering how resilient is it against common (D)DoS attacks(i.e. DNS amplification, UDP flood, etc.) given ...
1 vote
1 answer
119 views

If everyone used Tor, how would websites protect themselves from malicious traffic?

This question came after seeing CloudFlare captchas, forums outright banning Tor IPs to protect themselves from malicious traffic, and all manner of hurdles where sites simply don't want Tor traffic. ...
3 votes
1 answer
84 views

If my network link is subject to frequent, short, outages (a gentle form of DoS attack?), can this help promote other nodes to guard before mine?

My broadband provider in the UK is a very large telecoms company that was once state owned. I have an "unlimited" broadband contract with them so running my Tor (non-exit) relay with an advertised ...
1 vote
2 answers
319 views

DoS attacking Tor users

Let's say we have two users connected via a socket over Tor. Is there anyway for one user to DoS the other user, maybe by learning their real IP address? My end goal is to design a system that let ...
2 votes
1 answer
257 views

What prevents an arbitrarily long or cyclic cell relay in the network?

I'm sure there are mechanisms in place to prevent this, but what stops someone from making a circuit that is extremely long or cyclic, as to cause a DOS in the network? If possible, this would allow ...
2 votes
1 answer
116 views

What happens if I create a flood of hidden services?

I could generate a torrc like this: HiddenServiceDir /Library/Tor/var/lib/tor/hidden_service0/ HiddenServicePort 80 127.0.0.1:8080 HiddenServiceDir /Library/Tor/var/lib/tor/hidden_service1/ ...
5 votes
1 answer
116 views

How to protect against DoS but not harm Tor users

Often when websites want to protect themselves against Denial-of-Service attacks, they will limit the number of requests one IP address can make in a given span of time. Sometimes this practice ...