Matt Traudt

An onion (v3) a day keeps the bad guys away | About me

About Me

Posted on 28 Aug 2016 by Matt Traudt

Last upated 02 Jan 2019 at 10:01 am
Pinned post

I work for the Naval Research Lab doing research and development on Tor, and sometimes the Internet in general.


KIST: Kernel-Informed Socket Transport for Tor [pdf] [acm]
ACM Transactions on Privacy and Security (TOPS 2018)
Rob Jansen, Matthew Traudt, John Geddes, Chris Wacek, Micah Sherr, and Paul Syverson

Privacy-preserving Dynamic Learning of Tor Network Traffic [pdf] [data]
25th ACM Conference on Computer and Communication Security (CCS 2018)
Rob Jansen, Matthew Traudt, and Nick Hopper

HSTS Supports Targeted Surveillance [pdf] [foci]
8th USENIX Workshop on Free and Open Communications on the Internet (FOCI 2018)
Paul Syverson and Matthew Traudt

Tor’s Been KIST: A Case Study of Transitioning Tor Research to Practice [pdf] [arxiv]
Technical Report arXiv:1709.01044 [cs.CR] (arXiv 2017)
Rob Jansen and Matthew Traudt


Personal: sirmatt |at| ksu d0t edu
Tor: pastly |at| torproject d0t org
Work: matthew d0t traudt |at| nrl d0t navy d0t mil
GPG 0x83BCA95294FBBB0A


In general, you can find code I write in public on GitHub and on my Gitea server.

Simple Bandwidth Scanner

Project link

Some of the Tor directory authorities run bandwidth scanners to measure the bandwidth of relays and include their measurements in their network status votes. Clients use the consensus of these weights to inform their path selection process with the hope that every circuit they build will have roughly equal performance, regardless of the relays chosen. This achieves a form of load balancing.

Historically, the directory authorities that ran bandwidth scanners (bandwidth authorities), ran torflow. Time passed, it slowly become less maintained, and the collective knowledge of how it worked slipped away.

Simple Bandwidth Scanner (sbws) aims to be a quick to implement, easy to maintain replacement for torflow.


KIST is a new scheduler for Tor. It is merged into Tor code as of It prioritizes low-bandwidth, bursty traffic (web traffic) over high-bandwidth, continuous traffic. See my relevant publications for more information.

BM - Blog Maker

Project link

BM is barely maintained.

This blog-like website is created with bm.

BM is a set of scripts that use common GNU utilities to dynamically create a static blog. See the README at the project page linked above for more information.

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Don't HTTPS Your Onions

Posted on 20 Dec 2017 by Matt Traudt

Last upated 27 Dec 2017 at 2:22 pm

Unless you're an edge case (which you aren't).

Why you would want HTTPS

Let's talk about why you normally want HTTPS. Let me know if I missed something.

End-to-end encryption

You already get this with Tor.

Everything between your local Tor client (using Tor Browser? It runs Tor in the background) and the Tor client providing the onion service is encrypted. No Tor relay and no network-level adversary can tell what onion service you are visiting (which is actually better than what HTTPS-without-Tor to a regular website would get you).

If you're an onion service operator and you're at the sophistication level of taking advice from random blogs on the Internet, HTTPS doesn't help you here. If you're Facebook, Reddit, or YouTube, then you have a sizable datacenter(s) and are probably no longer running Tor on the same machines as your webservers. Unencrypted traffic may be flowing over an uncomfortable distance on your (super secure, right?) network. Maybe you want HTTPS. But you also have the resources to get a valid certificate for your onion. So do that.

Avoid men in the middle

You already get this with Tor. This is related, but distinct from the previous point.

When you connect to with HTTPS, how do you know no one is MitM'ing you? The certificate is valid, right? No big scary browser errors. For better or for worse, we trust the Certificate Authority (CA) system.

When you connect to an onion service, how do you know no one is MitM'ing you? Easy. It's impossible. The bad guy would have to be in your browser (more accurately: between the browser part of Tor Browser and the Tor process it runs in the background) or between the Tor process the onion service operator is running and the webserver it's pointing at. If you assume your Tor Browser

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Mosh over Tor (Except Not Really)

Posted on 18 Jun 2017 by Matt Traudt


I'm in the process of setting up a new server and I'm trying to be super ultra mega secure about it. It's running FreeBSD with some fancy security options enabled, blah blah blah, oh and I made SSH over Tor the only way to remotely access it for administration. It's a private onion service, which is super cool in itself, but since I don't mind leaking the location of this server, it is also a single-onion service. This does seem to have a positive impact on the speed and latency to the machine, but after a few weeks of managing the machine completely over Tor, I determined I wanted more usability.

My main complaint is the lack of immediate local echoing of what I type. Mosh does that, but mosh uses UDP, which doesn't work over Tor. There's two ways I could approach this. The first would actually be called "Mosh over Tor," but I ultimately went for the second as it would actually allow me to roam (another great feature of mosh).

  1. I could use socat to tunnel UDP over Tor. Create the tunnel and then mosh to localhost:some-port.

  2. Or I could authenticate over SSH over Tor and then create the actual UDP connection over the regular Internet.

So I now present to you the script I use to (not really) use mosh over Tor. It's a healthy mixture of things specific to me and hardcoded values that need changing for every use case. But it is a starting point if you would like to try your hand at (2) above too.

#!/usr/bin/env bash
SUCCESS_LINE=$(ssh $SSH_HOSTNAME "mosh-server new -i $MOSH_IP" | grep 'MOSH CONNECT')
[[ "$SUCCESS_LINE" == "" ]] && echo "failed to connect :(" && exit 1
MOSH_PORT=$(echo $SUCCESS_LINE | cut -d ' ' -f 3)
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The Last Onion Service Index

Posted on 06 May 2017 by Matt Traudt

Last upated 04 Feb 2018 at 11:28 am

I made a thing.

http://jld3zkuo4b5mbios.onion and http://vwx4mjvwoszgnagzcrwdjlsq3pq3zyob3zpq5qissxdoivnuyylzn7yd.onion (it used to be available at and ypqmhx5z3q5o6beg.onion)

Most of what I wanted to say about it I've already said at those links above.

It got picked up by Motherboard, and then a few other sites picked it up. This was supposed to be a stupid little Saturday project. It isn't interesting. It isn't exciting.

Creating Private Onion Services

Posted on 25 Feb 2017 by Matt Traudt

Last upated 14 Jan 2018 at 2:37 pm

You're probably aware of many of the great features of onion services.

You may have ever heard about how misbehaving relays with the HSDir flag can learn the existence of onion services that their owners literally never advertised anywhere. This attack and related attacks will be impossible when the next generation of onion services is deployed (see end of this post for more information), but did you know can prevent this from happening right now, today, on your onion services?

This is thanks to a feature of Tor onion services that can prevent anyone from even connecting to your service if they don't have your permission. I'm not talking about a login page on example.onion, I'm talking about the inability for random people to be able to tell that example.onion is up or if it even exists.

I'm talking about the HiddenServiceAuthorizeClient (server-side) and HidServAuth (client-side) torrc options that you can find in the Tor manual.

There are two ways to use this: basic and stealth. The gist with both is

After this setup is done, clients authenticate automatically with no further work from the user necessary.

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BM v4.0.0 is Released

Posted on 30 Jan 2017 by Matt Traudt


Yesterday I released yet another new major version of BM! The changelog has a summary of changes. As before, please report any issues at the issue tracker.


There are two big changes that should be noted.

Your configuration file needs to move. It used to be in include/bm.conf, but that directory has been emptied out. Your configuration file now belongs in your posts directory, posts/bm.conf. BM comes with a script in tools/ to help you transition from v3 to v4, but really it's as simple as moving your configuration file. After you've moved it, you may delete the include directory. It should be empty.

The other major change is themes! Themes allow you to quickly change the look of your website. They can easily be shared as all the important bits and pieces are in one directory per theme. Here's the "terminal" theme that I created and will officially support in addition to the default theme.

terminal theme

For information how how to set your theme, see here. For information about creating your own theme, see here. It's very easy, especially if you start out copy/pasting an already good one.

Other new features

Page signing was added. Now, given a gpg fingerprint, BM will automatically cryptographically sign all output files (even the CSS!) and leave a note in the footer saying so in officially supported themes.

signature note

(Ignore the version number, this was added in v4.0.0. I should probably decide something about "in development" versioning...)

If page signing is enabled, then /pubkey.gpg will also be automatically generated with the public key used for signing.

Licensing your content has been made easier. A new config option, LICENSE_TEXT, was added. The contents of it will be placed verbatim in the

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