telnet-socket

A standards compliant Telnet implementation for Node.js

Standards

In addition to RFC 854, a number of additional RFCs, proposed RFCs, and adopted options such as GMCP and MSSP are implemented. An emphasis on standards used with ANSI-BBS related terminals is taken, though PRs are certainly welcome if something of use is missing.

Some additional standards include:

• RFC 856 - Telnet Binary Transmission
• RFC 857 - Telnet Echo Option
• RFC 858 - Telnet Suppress Go Ahead Option
• RFC 1073 - Telnet Window Size Option
• RFC 1091 - Telnet Terminal-Type Option
• RFC 1572 - Telnet Environment Option

See telnet_spec.js for more information and additional standards.

Usage

const { TelnetSocket, TelnetSpec } = require('telnet-socket');

const telnetSocket = TelnetSocket(rawSocket);

//	request client to send NAWS
telnetSocket.do.naws();

telnetSocket.on('SB', command => {
	if (TelnetSpec.Options.NAWS === command.option) {
		// client sent us NAWS
		const { width, height } = command.optionData;
		// ...do something with height and width
	}
});

ℹ️ You can see example usage in ENiGMA 1/2 BBS here

The TelnetSocket Class

Properties

• passthrough: Set to true to enable passthrough mode. Defaults to false.
• escapeIACs: Set to false to disable escaping of telnet IAC characters. Defaults to true.
• rawSocket: Access the underlying socket.

Events

General

• data (data): Non-protocol data
• command error (command, error): An error ocurred whilest processing a command.
• end (): Socket end.
• error (error): A socket error has occurred.

Commands

Events are emitted for specific Telnet commands such as (but not limited to) DO, DONT, WILL, WONT and AYT with the signature of (command) where command has the following properties:

• code: The raw byte code of the command.
• name: The command name (DO, DONT, ...) or unknown comand.
• option: Option sent with the command.
• optionName: The name of the option such as NAWS or unknown option.
• optionData: For options that contain additional data. For example, NAWS contains height and width members, while TTYPE contains a ttype member.

Unknown commands are emitted as unknown command with the same signature described above.

FAQ

• Q: How do I receive characters instead of lines?
• A: Issue socket.will.sga()

License

See LICENSE.md