Player-session MUD protocol

MCCP2

MUD Client Compression Protocol v2

Widely used Documented current use

Compresses the complete server-to-client byte stream after a negotiated start marker.

Protocol overview

First seen: 2000
Present-day status: Widely used
In use today?: Yes, with documented current use.
Legacy?: No.
Layer: Player-session MUD protocol
Transport: Telnet option 86 followed by a zlib stream
Telnet option: 86
Research validated: 2026-08-29

Current use and fit

The mature and broadly implemented compression option for traditional MUD connections.

Implementation essentials

Send the MCCP2 start subnegotiation uncompressed, then immediately switch every outbound byte to zlib.
Place Telnet framing before compression and TLS after compression.
Make compression optional and manage flush behavior carefully.

Compatibility and safety notes

The marker itself is not compressed.
Later Telnet commands are inside the compressed stream.
Compression provides no confidentiality.

Original specifications and sources

MUDhalla MCCP specification Primary
MUD Standards preservation Preservation

Where an original site has disappeared, a preservation archive is linked and identified as such. MUDVerse does not claim authorship of the original protocol.