Tor bridges help users connect to the Tor network when regular access is blocked. Countries like China and Iran actively block Tor connections. Bridges provide alternative entry points not listed in public directories, bypassing censorship and allowing Tor access where it would otherwise be impossible.

Why Bridges Exist

Normal Tor entry guards are publicly listed in the Tor directory. This list helps users find entry points but also helps censors block them. Governments simply download the list and block all IP addresses.

Bridges are unlisted entry guards. They're not in the public directory. Censors can't easily find and block all bridges. Even if some bridges get discovered and blocked, new ones remain available.

Bridges serve one purpose: helping users in censored countries access Tor. If you can connect to Tor normally, you don't need bridges.

Types of Bridges

Plain Bridges

Basic bridges provide an unlisted entry point but don't disguise that you're using Tor. Your ISP sees Tor traffic, just to an unlisted address.

Plain bridges help against simple IP blocking but fail against deep packet inspection (DPI) that detects Tor's traffic patterns. Most modern censorship systems use DPI, making plain bridges insufficient.

Obfs4 Bridges

Obfs4 (obfuscation 4) makes Tor traffic look like random data. It disguises both the bridge address and the traffic pattern. DPI systems can't easily identify it as Tor.

Obfs4 is the most effective bridge type for countries with sophisticated censorship. It defeats both IP blocking and traffic analysis.

Snowflake

Snowflake uses temporary bridges provided by volunteers running browser extensions. These bridges change frequently and use web technologies (WebRTC) to disguise traffic.

Snowflake excels in environments actively hunting bridges because addresses change constantly. Even if censors block some Snowflake proxies, new ones appear immediately.

Meek

Meek bridges route traffic through major content delivery networks (CDNs) like Amazon CloudFront or Microsoft Azure. Blocking meek bridges requires blocking large portions of popular services, which most censors won't do.

Meek is slower than other bridge types because of the CDN routing but very effective against censorship.

Recommendation: For most censored countries, obfs4 bridges work well. If obfs4 gets blocked, try Snowflake. Meek is the last resort option when others fail.

Getting Bridge Addresses

BridgeDB Website

Visit bridges.torproject.org (on the regular internet before connecting to Tor). Solve the CAPTCHA and receive a few bridge addresses.

This method works if you can access the Tor Project website. In heavily censored countries, this site might be blocked.

Email

Send email to [email protected] from a Gmail, Riseup, or Yahoo address. The automated system replies with bridge addresses.

This works even if Tor Project websites are blocked, since email services are harder to censor completely.

Built-in Bridges

Tor Browser includes some built-in bridge addresses. These are convenient but might already be blocked in countries with aggressive censorship since they're built into every Tor Browser copy.

Private Bridges

Some individuals run private bridges and share addresses privately through trusted channels. These are hardest for censors to find but also hardest for users to obtain.

Configuring Bridges

First Launch Configuration

When first launching Tor Browser in a censored country, click "Configure Connection" instead of "Connect." Select "Tor is censored in my country" and choose a bridge type.

If using built-in bridges, select obfs4 or Snowflake. If you have custom bridge addresses, choose "Provide a bridge I know" and enter the addresses.

Adding Bridges Later

Open Tor Browser settings, navigate to Connection, and check "Use a bridge." Select your preferred bridge type or add custom bridges in the text box.

Restart Tor Browser after changing bridge configuration for changes to take effect.

Bridge Address Format

Bridge addresses look like: obfs4 [IP]:[port] [fingerprint] [parameters]. Copy the entire line when adding custom bridges.

Each bridge type has a specific format. Don't modify the addresses - paste them exactly as provided.

Testing and Troubleshooting

Connection Testing

After configuring bridges, Tor Browser attempts to connect. This takes longer than normal connections - be patient. Initial connections through bridges can take several minutes.

If connection succeeds, Tor Browser opens normally. If it fails after several minutes, try different bridges.

When Bridges Fail

If built-in bridges don't work, they're probably blocked. Request custom bridges via email or try a different bridge type.

Sometimes connection fails due to network issues unrelated to censorship. Try again later or from a different network.

Changing Bridge Types

If obfs4 doesn't work, try Snowflake. If Snowflake fails, try meek. Each bridge type uses different techniques, so one might work when others don't.

Using Bridges Safely

Don't Share Bridges Publicly

Bridge addresses shared publicly get discovered and blocked quickly. Keep bridge addresses private. Only share with trusted individuals who need them.

Use Multiple Bridges

Configure several bridge addresses. If one stops working, Tor automatically tries others. This provides redundancy against bridge blocking.

Update Regularly

Bridges get blocked over time. Request new bridges periodically even if current ones work. Having fresh bridges ready prevents connection loss when current bridges get blocked.

Running Your Own Bridge

Why Run a Bridge

Running a bridge helps people in censored countries access Tor. It's direct activism supporting internet freedom.

Bridges use minimal bandwidth and resources compared to exit nodes. Most home internet connections can handle a bridge.

Setup Requirements

You need a computer with stable internet connection and open ports. The computer must run continuously to be useful as a bridge.

Installation involves installing Tor software and configuring it as a bridge. The Tor Project provides detailed setup instructions for various operating systems.

Privacy Considerations

Bridge operators' IP addresses might be discovered by censors. This doesn't expose your browsing but might mark you as supporting Tor in countries hostile to it.

Consider the legal environment in your location before running a bridge. In most democratic countries, it's completely legal and safe.

Important: Bridges are entry points only. They don't see your destination traffic or browsing activity. Running a bridge is much safer than running an exit node.

Advanced Bridge Usage

Combining Bridges and VPN

Using VPN before Tor bridges adds another layer. Your ISP sees VPN traffic, not bridge connections. This can help in environments actively hunting Tor usage.

Connect to VPN first, then connect Tor with bridges through the VPN tunnel.

Pluggable Transports

Obfs4, Snowflake, and meek are all "pluggable transports" - modular systems for disguising Tor traffic. The Tor Project continues developing new transports to stay ahead of censorship.

Future Tor Browser versions might include new transport types. Always use the latest Tor Browser version for best censorship circumvention.

Country-Specific Advice

China

The Great Firewall actively blocks Tor. Use obfs4 bridges obtained via email. Snowflake works well in China. Built-in bridges are usually already blocked.

Consider using VPN before Tor for additional protection. Update bridges regularly as they get discovered and blocked.

Iran

Iran blocks Tor but less aggressively than China. Obfs4 bridges usually work. Snowflake provides good backup.

Iranian blocking increases during protests or political unrest. Have multiple bridge types configured.

Russia

Russia blocks Tor website access but direct Tor connections work in some regions. Bridges might not be necessary everywhere but are useful as backup.

Obfs4 bridges work when needed. Situation varies by region and ISP.

Limitations

Bridges don't guarantee access. Sophisticated censors can eventually discover and block popular bridges. This is an ongoing arms race.

Bridge connections are slower than direct Tor connections. The disguising process adds overhead. Expect reduced performance.

Bridges protect Tor access but don't hide that you're using encryption or privacy tools. Advanced monitoring might still flag your activity as suspicious even without identifying Tor specifically.

Staying Informed

Censorship techniques evolve. Stay informed about current bridge effectiveness in your region through forums and Tor Project announcements.

The Tor Project actively develops new anti-censorship tools. Following their blog and updates ensures you know about new options as they become available.

Final Thoughts

Bridges enable Tor access where it would otherwise be impossible. For users in censored countries, bridges are essential tools for accessing free information and anonymous communication.

Start with obfs4 bridges and have Snowflake configured as backup. Request new bridges regularly. Stay patient during connections - bypass takes time but works reliably when configured correctly.