One more hop for Kermit

Way back in the Good Old Days, when your editor was a VMS system administrator, the ARPAnet was small, slow, and extremely limited in access. While some of the cooler folks were building USENET around uucp-based links, Unix systems were still not readily available to most of us. But we were beginning to get personal computers, bulletin-board systems were being set up, and the fortunate among us could afford 1200 baud modems. The tool of choice for using those modems in those days was often a little program called "Kermit," which was freely downloadable even then. Your editor doesn't remember when he last used a modem, but he was still interested to see that this 30-year-old project is about to go through a final transition; it will, among other things, be free software at last.

For many systems in those days - especially systems without a government budget behind them - the "network interface" was the serial port. That's how we connected to The Computer at work; that's also how we got onto the early services which were available in those days. The first thing any RS232 networking user needed was a way to move keystrokes between one interface (where they sat) and the interface connected to the modem. Unix systems often came with a tool called "cu" for that purpose, but, even on those systems, users tended to gravitate toward a newish tool called Kermit instead.

Kermit has its roots at Columbia University, where it was developed as a way to communicate between computers on a heterogeneous network. It would fit easily onto a floppy and was (unlike cu) easy to set up and use; one just needed to figure out how many data bits, how many stop bits, and what kind of parity to use (RS232 is a fun "standard"), type an appropriate ATD command at the modem, and go. Kermit could even handle things like translating between different character sets; talking to that EBCDIC mainframe was not a problem.

Over a short period of time, Kermit developed some reasonable file transfer capabilities. Its protocol was efficient enough, but it was also designed to deal with serial ports which might interpret control characters in unexpected ways, turn eight-bit data into seven-bit data, and more. The robustness of the protocol meant it "just worked" between almost any two arbitrary types of machines. So it's not surprising that, in those pre-Internet days, Kermit became a popular way of moving files around.

Columbia distributed a number of versions of Kermit in source form; it could be had from bulletin board sites, DECUS tapes, and more. The program was never released as free software, though. When Kermit was first coming into use, free software licenses as such didn't exist yet. The university considered releasing the code into the public domain but decided that it wasn't a good idea:

The license for Kermit varied over time, but was always of the "you may make noncommercial use of this program" variety. The final version of the Kermit license allowed bundling the program with free operating systems, but did not allow modifications to the source without permission. As a result, despite the fact that Kermit's license allowed distribution with systems like Linux, most distributors eventually shied away from it because it was not truly free software.

Anybody other than free operating system projects wanting to distribute Kermit commercially had to buy per-seat licenses (at a cost of $3-10 each) from Columbia.

Kermit has proved remarkably durable over the years. During Kermit's lifespan, the Internet has taken over, even our phones can run ssh, and RS232-based communications have mostly fallen by the wayside. Kernel developers are still known to use serial consoles for some types of debugging, but your editor would predict that a substantial portion of the rest of LWN's readership has never had to wonder where that null modem cable went to. Kermit's user base must certainly be shrinking, but it is still being maintained and sold to those who need it.

Or, it least, it was; in March the university announced that it was unable to continue supporting the Kermit project. One assumes that commercial license sales had finally dropped to the point where they weren't worth the administrative overhead of dealing with them. As of July 31, 2011, the university will put no further development effort into Kermit and will no longer provide support and maintenance services. A three-decade project is coming to a close.

Columbia University is doing one more thing with Kermit before the end, though - it is releasing the software under the BSD license. C-Kermit 9.0 will carry that license; the first beta release was made on June 15. The 9.0 release will also support the FORCE-3 packet protocol ("for use under severe conditions"), improved scripting, various fixes, and more. So the 9.0 release, presumably scheduled for sometime close to the July 31 deadline, will not just have new features; it will be free software for the first time.

As a result of this change, Kermit may soon show up in a distribution repository near you; most Linux users are, at this point, unlikely to care much. But, for many of us, there will yet come a time when the only way to talk to a system of interest is through a serial connection. Kermit is far from the only option we have at this point, needless to say, but it's a good one. Kermit's hop into the the free software community is more than welcome.

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