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Contents

• Contents
• About
  • Using Zebra
• Release Candidates
• Getting Started
  • Docker
  • Building Zebra
    • Optional Features
  • Configuring JSON-RPC for lightwalletd
  • Network Ports
• Known Issues
• Future Work
• Documentation
• Security
• License

About

Zebra is the Zcash Foundation's independent, consensus-compatible implementation of a Zcash node, currently under development. It can be used to join the Zcash peer-to-peer network, which helps keeping Zcash working by validating and broadcasting transactions, and maintaining the Zcash blockchain state in a distributed manner.

Zcash is a cryptocurrency designed to preserve the user's privacy. If you just want to send and receive Zcash then you don't need to use Zebra directly. You can download a Zcash wallet application which will handle that for you.

Please join us on Discord if you'd like to find out more or get involved!

Using Zebra

You would want to run Zebra if you want to contribute to the Zcash network: the more nodes are run, the more reliable the network will be in terms of speed and resistance to denial of service attacks, for example.

Zebra aims to be faster, more secure, and more easily extensible than other Zcash implementations.

Release Candidates

Every few weeks, we release a new Zebra version.

Zebra's network stack is interoperable with zcashd, and Zebra implements all the features required to reach Zcash network consensus. Currently, Zebra validates all of the Zcash consensus rules for the NU5 network upgrade.

Zebra validates blocks and transactions, but needs extra software to generate them:

• to generate transactions, configure zebrad's JSON-RPC port, and use a light wallet with lightwalletd and Zebra.
• to generate blocks, compile zebrad with the getblocktemplate-rpcs feature, configure the JSON-RPC port, and use a mining pool or miner with Zebra's mining JSON-RPCs. Mining support is currently incomplete, experimental, and off by default.

Getting Started

You can run Zebra using our Docker image or you can build it manually. Please see the requirements section of the Zebra Book for system requirements.

Docker

This command will run our latest release, and sync it to the tip:

docker run zfnd/zebra:1.0.0-rc.8

For more information, read our Docker documentation.

Building Zebra

Building Zebra requires Rust, libclang, pkg-config, and a C++ compiler.

Zebra is tested with the latest stable Rust version. Earlier versions are not supported or tested. Note that Zebra's code currently uses features introduced in Rust 1.68, or any later stable release.

Below are quick summaries for installing the dependencies on your machine.

General instructions for installing dependencies

1. Install cargo and rustc.

2. Install Zebra's build dependencies:

   • libclang is a library that might have different names depending on your package manager. Typical names are libclang, libclang-dev, llvm, or llvm-dev.
   • clang or another C++ compiler: g++ (all platforms) or Xcode (macOS).
   • pkg-config

Dependencies on Arch

sudo pacman -S rust clang pkgconf

Note that the package clang includes libclang as well as the C++ compiler.

Once the dependencies are in place, you can build Zebra

cargo install --locked --git https://github.com/ZcashFoundation/zebra --tag v1.0.0-rc.8 zebrad

You can start Zebra by

zebrad start

See the Running Zebra section in the book for more details.

Optional Features

You can also build Zebra with the following Cargo features:

• sentry for Sentry monitoring;
• filter-reload for dynamic tracing
• journald for journald logging.
• flamegraph for generating flamegraphs.
• prometheus for Prometheus metrics.
• getblocktemplate-rpcs for mining support.

You can arbitrarily combine the features by listing them as parameters of the --features flag:

cargo install --features="<feature1> <feature2> ..." ...

The features are also described in the API documentation. The debugging and monitoring features are disabled in release builds to increase performance.

Configuring JSON-RPC for lightwalletd

To use zebrad as a lightwalletd backend, give it this ~/.config/zebrad.toml:

[rpc]
# listen for RPC queries on localhost
listen_addr = '127.0.0.1:8232'

# automatically use multiple CPU threads
parallel_cpu_threads = 0

WARNING: This config allows multiple Zebra instances to share the same RPC port. See the RPC config documentation for details.

lightwalletd also requires a zcash.conf file.

It is recommended to use adityapk00/lightwalletd because that is used in testing. Other lightwalletd forks have limited support, see the detailed lightwalletd instructions.

Network Ports

Zebra uses the following inbound and outbound TCP ports:

• 8233 on Mainnet
• 18233 on Testnet

Please see the Network Requirements section of the Zebra book for more details.

Known Issues

There are a few bugs in Zebra that we're still working on fixing:

• If Zebra fails downloading the Zcash parameters, use the Zcash parameters download script instead.

• Block download and verification sometimes times out during Zebra's initial sync #5709. The full sync still finishes reasonably quickly.

• No Windows support #3801. We used to test with Windows Server 2019, but not any more; see the issue for details.

• Experimental Tor support is disabled until Zebra upgrades to the latest arti-client. This happened due to a Rust dependency conflict, which could only be resolved by arti upgrading to a version of x25519-dalek with the dependency fix.

• Output of help, --help flag, and usage of invalid commands or options are inconsistent #5502. See the issue for details.

Future Work

Performance and Reliability:

• Reliable syncing under poor network conditions
• Additional batch verification
• Performance tuning

Currently, the following features are out of scope:

• Optional Zcash network protocol messages
• Consensus rules removed before Canopy activation (Zebra checkpoints on Canopy activation)

Documentation

The Zebra website contains user documentation, such as how to run or configure Zebra, set up metrics integrations, etc., as well as developer documentation, such as design documents. We also render API documentation for the external API of our crates, as well as internal documentation for private APIs.

Security

Zebra has a responsible disclosure policy, which we encourage security researchers to follow.

License

Zebra is distributed under the terms of both the MIT license and the Apache License (Version 2.0).

See LICENSE-APACHE and LICENSE-MIT.