[tor-talk] Invitation to try experimental Snowflake Tor Browser packages

David Fifield david at bamsoftware.com
Sat May 23 19:28:09 UTC 2020

These experimental session persistence features for Snowflake are now
standard in Tor Browser 9.5a13.


To enable Snowflake the first time you run the browser:
 * Click "Configure"
 * Click "Tor is censored in my country"
 * Click "Select a built-in bridge"
 * Select "snowflake" from the menu
If the browser is already running:
 * Go to about:preferences#tor (open the Preferences menu then click Tor
   on the left side)
 * Look at the "Bridges" section
 * Click "Use a bridge"
 * Click "Select a built-in bridge"
 * Select "snowflake" from the menu

Logging is disabled by default. To enable Snowflake logging, edit the
file Browser/TorBrowser/Data/Tor/torrc-defaults (or
Contents/Resources/TorBrowser/Tor/torrc-defaults on Mac) and append the
following options to the ClientTransportPlugin snowflake line:
	-log snowflake-client.log -log-to-state-dir
The log will appear in
Browser/TorBrowser/Data/Tor/pt_state/snowflake-client.log (or

Depending on what kind of NAT you have, it may take several minutes to
connect (or reconnect, when a proxy disappears).

On Wed, Feb 26, 2020 at 11:02:10PM -0700, David Fifield wrote:
> The anti-censorship team is looking for people to try Tor Browser
> packages built from an experimental branch of Snowflake that is supposed
> to make Snowflake more reliable. There are two versions; you can try
> either one or both of them. If you have feedback, tell us whether you
> are using the "kcp" or "quic" version.
> What's different about these experimental packages? As you may know,
> Snowflake is already part of alpha Tor Browser. Snowflake works by
> routing your connection through temporary proxies before they reach a
> bridge, but until now there wasn't a way to switch to a new proxy when
> the one you are using stops working--the connection would just stop
> working. These packages solve the problem by putting a session protocol
> under the temporary Snowflake layer. (That's why there are two options.
> We are testing two session protocols: KCP and QUIC.) If you are curious
> about the background:
> https://lists.torproject.org/pipermail/anti-censorship-team/2020-February/000074.html
> https://bugs.torproject.org/33336
> https://github.com/net4people/bbs/issues/9
> These special packages are made not to auto-update until 2020-04-23.
> After that, they will update and become a normal Tor Browser alpha.
> What to expect. You should be able to use these browsers all day without
> the connection breaking. The speed of the Snowflake connection depends
> on the temporary proxy you get assigned. If you think you have a slow
> proxy, try this trick: go to about:preferences#tor, switch to obfs4 for
> 1 second, then switch back to snowflake. That will restart the pluggable
> transport and give you a chance at a different proxy. It takes 30
> seconds to detect a failed proxy. So if your proxy dies, it will be at
> least 30 seconds before your connection starts working again. It may be
> even longer than that, if you happen to be assigned another bad proxy
> right away. You can see what's going on by watching the log file:
> 	linux:   Browser/TorBrowser/Data/Tor/pt_state/snowflake-client.log
> 	windows: Browser\TorBrowser\Data\Tor\pt_state\snowflake-client.log
> 	mac: Tor Browser.app/Contents/Resources/TorBrowser/Tor/pt_state/snowflake-client.log
> Here's a guide to reading the log file:
> Traffic Bytes (in|out): 0 | 972
> Traffic Bytes (in|out): 52457 | 7270
> 	If the number on the left stays at 0, the proxy isn't working.
> 	If it's nonzero, the proxy is working.
> WebRTC: No messages received for 30s -- closing stale connection
> redialing on same connection
> 	This means that your proxy died and the system is switching to a
> 	new one.
> It's possible to run multiple Tor Browsers at the same time, if you want
> to run one of these Snowflake browsers alongside your normal Tor
> Browser, or run the "kcp" and "quic" versions at the same time. I posted
> instructions to https://lists.torproject.org/pipermail/anti-censorship-team/2020-February/000074.html
> but the short summary is you have to set a couple of environment
> variables:
> 	TOR_SOCKS_PORT=9250 TOR_CONTROL_PORT=9251 ./start-tor-browser.desktop

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