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What is Kermit?

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Kermit is the name of a file-transfer protocol and a suite of computer programs for many types of computers that implement that protocol as well as other communication functions ranging from terminal emulation to automation of communications tasks through a high-level cross-platform scripting language. The software is transport-independent, operating over TCP/IP connections in traditional clear-text mode or secured by SSH, SSL/TLS, or Kerberos, as well as over serial-port connections, modems, and other communication methods.

The Kermit Project was founded at the Columbia University Computer Center (now CUIT) in 1981, and until the mid- to late 1990s, Kermit was Columbia's standard connectivity software, used by students, faculty, and staff to connect from desktop microcomputers, PCs, Macintoshes, and Unix workstations tothe central computing facilities: the IBM mainframes, the DECSYSTEM-20s, CLIO, and Cunix (our Unix-based severrs). At Columbia, the mainframes and DEC-20s are long gone, but Kermit still may be used for SSH sessions to CUNIX.

Over the years, the Kermit Project grew into a worldwide cooperative nonprofit software development and distribution effort, headquartered at and coordinated from Columbia University. The Kermit Project is dedicated to production of cross-platform, long-lasting, standards-conformant, interoperable communications software, and is actively engaged in the standards process. Kermit software is used all over the world in every sector of the economy.

Although terminal emulation has been largely supplanted by the Web for online access, Kermit software continues to play a role in other applications such as remote sensing and data collection, remote management and troubleshooting of networking and telecommunications equipment, cargo management, medical insurance claim submission, electronic funds transfer, and online filing of income tax returns. Kermit software is embedded in cash registers, network routers, cell-phone towers, medical diagnostic and monitoring equipment, die-cutting and stamping presses, even cardiac pacemakers.

The Kermit protocol and software are named after Kermit the Frog, star of the television series, The Muppet Show; the name Kermit is used by permission of Henson Associates, Inc.


Kermit software has been written for hundreds of different computers and operating systems, some of it by volunteer programmers all over the world, some of it by the Kermit Project professional staff. The major features of the most popular Kermit programs are:

Kermit's user interface and script programming language are consistent across platforms and communication methods, allowing the investment in learning to pay off time and again as you move from one platform to another, one communication method to another.

Our premiere Kermit software implementations are:

Kermit 95 and MS-DOS Kermit are full-featured communication software programs rivaling the quality of anything else on the market. C-Kermit for UNIX, VMS, etc, and IBM Mainframe Kermit are host-based packages with an unequaled range of versatility. We document this software thoroughly and support and develop it aggressively. And unlike most other providers of communications software, we supply and can support the software for both ends of the connection.


Since its inception in 1981, the Kermit protocol has developed into a sophisticated and powerful transport-independent tool for file transfer and management, incorporating, among other things:

The feature that distinguishes Kermit protocol from most others is its wide range of settings to allow adaptation to any kind of connection between any two kinds of computers. Most other protocols are designed to work only on certain kinds or qualities of connections, and/or between certain kinds of computers, and therefore work poorly (or not at all) elsewhere and offer few if any methods to adapt to unplanned-for situations. Kermit, on the other hand, allows you to achieve successful file transfer and the highest possible performance on any given connection.

Unlike FTP or X-, Y-, and ZMODEM (the other protocols with which Kermit is most often compared) Kermit protocol does not assume or require:

(although Kermit does not require any of these conditions, it can take advantage of them when they are available). A feature article on Kermit protocol by Tim Kientzle in the February 1996 issue of Dr. Dobb's Journal noted that "Kermit's windowing approach is faster than protocols such as XModem and YModem . . . What many people don't realize is that under less-than-ideal conditions, Kermit's windowing approach is significantly faster than ZModem, a protocol with a well-deserved reputation for fast transfers over good-quality lines."

Thus Kermit transfers work "out of the box" almost every time.

The Kermit file transfer protocol specification is given in the book, Kermit, A File Transfer Protocol.

A formal specification and verification of the Kermit protocol was published by James Huggins of the University of Michigan in 1995.


Kermit Protocol / Columbia University / kermit@columbia.edu / 26 October 2006