A testable implementation of telnet, and as many of its RFCs as are viable, for .NET. Written with MUDs in mind: every telnet option is a plugin you opt into, the interpreter is a state machine over the byte stream, and every outgoing write is serialized for you.
dotnet add package TelnetNegotiationCore- Documentation — guides, concepts and reference.
- Protocols — every RFC and MUD specification supported, one page each.
- Getting started — one connection, end to end.
- Changelog · Security policy · Discord
BuildAndStartAsync wires the connection and starts the read loop. Pass an IDuplexPipe (Kestrel's
connection.Transport), a TcpClient, or a raw Stream:
var (telnet, readTask) = await new TelnetInterpreterBuilder()
.UseMode(TelnetInterpreter.TelnetMode.Server)
.UseLogger(logger)
.OnSubmit(HandleSubmitAsync)
.AddPlugin<NAWSProtocol>()
.OnNAWS(HandleWindowSizeAsync)
.AddPlugin<GMCPProtocol>()
.OnGMCPMessage(HandleGMCPAsync)
.AddPlugin<MSSPProtocol>()
.WithMSSPConfig(() => new MSSPConfig { Name = "My Server", UTF_8 = true })
.BuildAndStartAsync(connection.Transport);
await readTask; // completes when the connection closesAddDefaultMUDProtocols() registers the nine a MUD usually wants in one call, and
AddTelnetServer() / AddTelnetClient() register the whole thing with the DI container. See
Getting started.
Each row is a plugin you register, and one page in the protocol reference.
| Specification | Specification | ||
|---|---|---|---|
| RFC 855 | Telnet Option Specification | MSSP | Mud Server Status Protocol |
| RFC 857 | Echo | MSDP | Mud Server Data Protocol |
| RFC 858 | Suppress Go-Ahead | GMCP | Generic Mud Communication Protocol |
| RFC 885 | End Of Record | EOR | End Of Record |
| RFC 1073 | Window Size (NAWS) | MTTS | Terminal type capabilities |
| RFC 1079 | Terminal Speed | MNES | Mud New Environment Standard |
| RFC 1091 | Terminal Type | MCCP | Compression, 2 and 3 |
| RFC 1096 | X-Display Location | MXP | MUD eXtension Protocol (option 91) |
| RFC 1184 | Line Mode (MODE) | MCP 2.1 | MUD Client Protocol, with cords |
| RFC 1372 | Flow Control | RFC 1950 | ZLIB compression |
| RFC 1408 | Environment | RFC 2066 | Charset, including TTABLE |
| RFC 1572 | New Environment | RFC 2941 | Authentication |
| RFC 2946 | Encryption | ||
| Pueblo | Pueblo handshake (in-band, no option) |
Being a telnet negotiation library, it does not render the content layers that ride on top: ANSI, Pueblo, and MXP's own tags are the host application's to draw. MXP is negotiated and Pueblo is handshaken; neither's markup is parsed.
Stable. The package targets netstandard2.0, net8.0, net10.0 and net11.0. Building from source
needs the .NET 11 SDK (RC1 or later), which global.json pins.
Releases are published from GitHub Actions by trusted publishing — no long-lived key exists — and carry an attestation of the workflow and commit that built them:
gh attestation verify TelnetNegotiationCore.3.0.0.nupkg --repo HarryCordewener/TelnetNegotiationCoreIssues and pull requests are welcome — see CONTRIBUTING.md for how to build and test, and SECURITY.md for anything that should not be public.