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Snowflake bridge survival guide
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===============================
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IP addresses:
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```
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37.218.242.151
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```
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SSH fingerprints:
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* `2048 SHA256:bP9tfPeIqkZkeKK1wcNT5t3CLyePz8oglFLRcdlP+gQ root@node (RSA)`
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* `1024 SHA256:ji5FxcUh6gjLj7RHl6ffHTRMW62Gp+8ZmGoL0p5nVl0 root@node (DSA)`
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* `256 SHA256:rl1WUhqOk3D2h2hwcK4x2HRPcnowUJuKnxQXYXOCXuk root@node (ED25519)`
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Tor fingerprints:
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```
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2048 SHA256:bP9tfPeIqkZkeKK1wcNT5t3CLyePz8oglFLRcdlP+gQ (RSA)
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1024 SHA256:ji5FxcUh6gjLj7RHl6ffHTRMW62Gp+8ZmGoL0p5nVl0 (DSA)
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256 SHA256:rl1WUhqOk3D2h2hwcK4x2HRPcnowUJuKnxQXYXOCXuk (ED25519)
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```
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* Bridge fingerprint 2B280B23E1107BB62ABFC40DDCC8824814F80A72
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* Hashed fingerprint 5481936581E23D2D178105D44DB6915AB06BFB7F
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* https://metrics.torproject.org/rs.html#details/5481936581E23D2D178105D44DB6915AB06BFB7F
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* [Relay search page](https://metrics.torproject.org/rs.html#details/5481936581E23D2D178105D44DB6915AB06BFB7F)
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## Components
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Upgrading snowflake-server. You need to give the new binary permission to bind ports 443 and 80. This cheat sheet is also commented in `/etc/tor/torrc`.
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1. `service tor stop`
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2. `install --owner root ~/new-server /usr/local/bin/snowflake-server`
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3. `setcap 'cap_net_bind_service=+ep' /usr/local/bin/snowflake-server`
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4. `service tor start`
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Check /var/log/syslog and /var/log/tor/snowflake-server.log for error messages. If there are `bind: permission denied` errors, ensure that you have run the `setcap` command, and that the tor `NoNewPrivileges=no` configuration from the [Snowflake Bridge Installation Guide](Survival Guides/Snowflake Bridge Installation Guide) is in place.
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The interacting components on the bridge are a bit complicated, for performance reasons. See the [installation guide](Survival Guides/Snowflake Bridge Installation Guide#introduction) for the reasoning. There are four main components:
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Standalone proxy-go instances
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-----------------------------
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* [snowflake-server](https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/tree/main/server): Receives WebSocket connections from Snowflake proxies, manages Turbo Tunnel sessions, forwards sessions as TCP connections to HAProxy. Listens externally on port 443 (and port 80, for ACME certificate renewal).
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* [HAProxy](https://www.haproxy.org/): Load balancer. Receives connections from snowflake-server and balances them over the multiple instances of tor, via their respective extor-static-cookie interfaces. Listens on 127.0.0.1:10000.
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* tor: There are multiple instances of tor, because one is not enough for the load on the bridge. Each instance's `ORPort` is blocked from outside access by the firewall, and `ExtORPort auto` makes them listen for ExtORPort connections on an ephemeral localhost port. Each instance of tor runs an extor-static-cookie, which provides HAProxy a stable ExtORPort port number, and provides snowflake-server (via HAProxy) a stable authentication key.
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* [extor-static-cookie](https://gitlab.torproject.org/dcf/extor-static-cookie): Exposes an ExtORPort interface that uses an unchanging authentication key. These listen on 127.0.0.1, on port numbers 10000+*N*, where *N* is the instance number 1, 2, ….
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## Upgrading snowflake-server
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The standalone proxy-go instances are managed by runit. You can see a list of possible instances under `/etc/service`. They are set up to periodically restart themselves in case of a hang.
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```
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sv status snowflake-proxy-standalone-17h # check status
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sv start snowflake-proxy-standalone-17h # start
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sv stop snowflake-proxy-standalone-17h # stop
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ps xww | grep runsvdir # check for error in the run script
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# install --owner root /home/user/snowflake-server /usr/local/bin/
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# service snowflake-server restart
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```
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Logs are stored in `/home/snowflake-proxy/*.log.d`.
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Upgrading proxy-go. Copy the binary to /usr/local/bin/proxy-go, then run:
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Check for errors in `service snowflake-server status` and /var/log/snowflake-server/snowflake-server.log.
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See /etc/systemd/system/snowflake-server.service for configuration variables.
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## Upgrading extor-static-cookie
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```
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sv restart snowflake-proxy-standalone-17h
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sv restart snowflake-proxy-standalone-29h
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# install --owner root /home/user/extor-static-cookie /usr/local/bin/
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# service tor restart
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```
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(Adjust as needed if there are other named services under /etc/service.)
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Adding a new instance:
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The static ExtORPort authentication cookie does not need to be stable long-term. If it accidentally gets lost or damaged, you can create a new one using the [gen-auth-cookie](https://gitlab.torproject.org/dcf/extor-static-cookie/-/blob/main/gen-auth-cookie) script in the extor-static-cookie source code. You will need to restart tor and snowflake-server.
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```
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cd /etc/runit
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mkdir -p my-instance/log
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cat > my-instance/run <<EOF
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#!/bin/sh
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exec chpst -u snowflake-proxy timeout 17h /usr/local/bin/proxy-go -broker https://snowflake-broker.bamsoftware.com/ 2>&1
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EOF
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cat > my-instance/log/run <<EOF
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#!/bin/sh
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exec chpst -u snowflake-proxy svlogd /home/snowflake-proxy/my-instance.log.d
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EOF
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chmod +x my-instance/run my-instance/log/run
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cd /etc/service
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ln -s /etc/runit/my-instance/
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mkdir /home/snowflake-proxy/my-instance.log.d
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chown snowflake-proxy:nogroup /home/snowflake-proxy/my-instance.log.d
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sv start my-instance
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# extor-static-cookie/gen-auth-cookie > static_extended_orport_auth_cookie
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# service tor restart
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# service snowflake-server restart
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```
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Firewall configuration is in `/etc/ferm/ferm.conf`. Run `service ferm restart` after making changes. |
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\ No newline at end of file |
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## Adding more tor instances
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See the [installation guide](Survival Guides/Snowflake Bridge Installation Guide#tor). After creating the tor instances, you will also have add new `server` lines in the `backend tor-instances` section of /etc/haproxy/haproxy.cfg.
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## Firewall
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Firewall configuration is in `/etc/ferm/ferm.conf`. Run `service ferm restart` after making changes. |
