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Hysteria 2 vs Hysteria 1

Hysteria 2 inherited almost all features of Hysteria 1.x while introducing a variety of new fixes and enhancements. It's important to note, however, that the protocol and codebase have undergone significant changes and as a result, Hysteria 2 is NOT compatible with Hysteria 1.x. Users must choose either 1.x or 2.x for both the client and server.

Key improvements

Some of the most notable include:

  • New Protocol: The redesigned protocol can masquerade as HTTP/3 to increase censorship resistance.
  • 0-RTT UDP Session Establishment: No delay for the first packet of a UDP session.
  • New ACL and Outbound System: Use different outbounds for different requests.
  • Traffic Stats API: For easier monitoring and management.
  • Performance Improvements: Various enhancements under the hood to improve performance and stability.

Missing features

There are some features present in Hysteria 1.x that have not yet been implemented in Hysteria 2:

  • Client-Side ACL: ACL is only available on the server side for now.
  • FakeTCP Protocol: FakeTCP has always been a somewhat niche feature and we are still evaluating whether to bring it back.