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Ethereum: WebSocket Handshake Rejected by Remote Peer
When building blockchain applications, especially those involving Ethereum (ERC-20 tokens), it is not uncommon to encounter issues with WebSocket connections, including the handshake. This process is critical for establishing real-time communication between a client application (e.g., a web interface) and a server or API. In this article, we will look at why establishing a WebSocket connection can be rejected by remote peers, and provide guidance on troubleshooting and resolving the issue.
What is a WebSocket Handshake?
A WebSocket handshake is a protocol used to establish a two-way communication channel between two parties over the web. It involves several steps:
- Handshake Initiation: The client (e.g., your web interface) sends a “WebSocket” connection request to the server.
- Server Authentication: The server verifies the identity of the client and checks for any security vulnerabilities.
- Handshake Negotiation: If authentication is successful, the client and server agree on a WebSocket version and encryption method.
- Establishing a Connection: Once agreed upon, the connection is established.
Ethereum Specifics
In Ethereum, establishing a WebSocket connection involves several unique steps:
- ERC-20 Token Connection Request: When a user initiates a WebSocket connection to access an ERC-20 token or smart contract, the client sends a
WebSocketconnection request.
- ERC-20 Token Verification: The server verifies the identity of the user and checks for any security vulnerabilities associated with ERC-20 tokens.
- Handshake Negotiation: If the authentication is successful, the client and server negotiate the WebSocket version and encryption method using their own keys (e.g.
x-ecDSA-256).
- Connection Establishment: Once agreed upon, the connection is established.
Why is the WebSocket Handshake Rejected?
If problems occur during the handshake process, there are several possible causes:
- Invalid Server Certificate
: The server certificate may not match the expected client authentication criteria.
- Insufficient Trust Anchor: The server may not have a trust anchor (e.g. a trusted certificate list) that allows it to verify the identity of clients.
- Certificate Verification Error: The server certificate verification process may fail, causing the connection to be refused.
Troubleshooting Steps
To troubleshoot issues while establishing a WebSocket connection, follow these steps:
- Verify Server Certificate
: Ensure that the server certificate matches your expected authentication criteria using tools like OpenSSL or Certbot.
- Install Trust Anchor: Install a list of trusted certificates (e.g. Bearer Trust Anchor) on your server to enable trust anchor verification.
- Configure WebSocket Connection: Review and update your client application code to ensure proper configuration for the custom keys used during the handshake.
Conclusion
Establishing a reliable WebSocket connection with Ethereum requires attention to detail and a thorough understanding of the protocol involved. By following these steps and troubleshooting common issues, you should be able to resolve the WebSocket Connection Refused error and successfully establish real-time communication between your client application and the server or API.
Be sure to regularly review and update your code to ensure compliance with evolving security standards and best practices for blockchain applications.
