PUB400: Your Free IBM i Playground

March 4, 2024 Alex Woodie

Search the Web for “free Linux server” and hundreds of results pop up. Do the same for “free IBM i server” and your results are much more limited. But what the universe of free IBM i servers lacks in quantity it makes up in quality thanks in large part to PUB400, a free IBM i instance that has been serving the midrange community for nearly a quarter century.

Many IT Jungle readers undoubtedly are familiar with PUB400.com, which was started by Holger Scherer on a little AS/400 Model 150 back in 1999. Over the years, the site and the IBM machines behind it have provided invaluable resources for beginners and experts alike. Tens of thousands of people have used PUB400 to play around with new tools, develop and test new programs, and learn to interact with a live instance of the OS/400, i5/OS, and now IBM i operating system.

Perhaps because PUB400 has been around so long, and kept a relatively low profile for that time, we haven’t given Scherer and PUB400 the credit they deserve. But with an eye-popping 40,000 users on PUB400, it’s time that we highlight this great IBM i resource. File this one under the “better late than never” category.

Humble Beginnings

Dial the clock back to 1999. The dot-com balloon was inflating fast, the Y2K “crisis” was in full swing, and AS/400s were selling like hotcakes. (It’s true. The AS/400 base peaked at 275,000 unique customers in 1998.) Amid the hectic midrange activity, a German programmer named Holger Scherer decided to do something novel: He wanted to fire up a small AS/400 and put it on the open Web.

“Around 1999, I bought a used 9401-150 for starting my entrepreneurship as programmer and systems operator,” Scherer told IT Jungle in an online interview. “I had a leased line with eight fixed IPs at home, and I used the box from my then-current employer.”

Accessing host environments is old hat today, but back in 2000, at the dawn of the Internet age, it was still a rather novel concept. While Unix types perhaps were more familiar with dialing into hosts over the network, it wasn’t something that came naturally to the business-focused AS/400 community. Since nobody knew about this new thing called PUB400, Scherer came up with a clever way to get the word out.

“In a forum post there was a discussion about security and Linux,” Scherer says. “I jumped in and told them about security on AS/400, which nobody knew. So I created a user ‘HACKER’ with same password and told them. They started to poke the box. Some weeks later the first people came and asked for their own user profile.”

Building A Community

Traffic built from there. Over the years, tens of thousands of people have signed up for a free account on PUB400, where they can learn the ins and outs of the IBM i operating system, play around with utilities, and maybe do some programming on RPG, or even Node.js.

Most of the early users who arrived on PUB400 didn’t know what an AS/400 was, Scherer says. Scherer did his best to provide them training resources, which has turned out well.

“Most of them had not see an AS/400 before,” he says. “They came from Linux or Windows. Then they started learning RPG. For the German users I wrote an ebook as a beginner’s guide . . . Nowadays we have a lot of international resources on the Internet for starters.”

There are, of course, rules to PUB400. As a public resource, it’s susceptible to abuse, so Scherer does his best to make sure everybody knows what they can and can’t do.

Holger Scherer

For starters, each user is allowed only one user profile, with PGMR-level access to data, programs, and objects. Commercial workloads are not allowed. Scherer doesn’t run regular backups, and makes no guarantees that the system will be available. There are restrictions on the number of connections you can have from a single IP address, and there are also restrictions on excluding other user profiles from your library. Global server variables cannot be changed.

With that said, PUB400 is surprisingly generous in providing resources. Everybody gets their own user profile equipped with 500 MB of disk storage and two private libraries. Users coming in via 5250 emulators have access to all the facilities that commonly come with the IBM i operating system, but don’t expect the more advanced licensed program products. Several free utilities are available on the site, including Bob Cozzi’s iQuery, the IBM i report server from KDP Software, and the physical file description utility FFD by Aldo Succi.

Hardware Refresh

When the 9401-150 became too slow, Scherer upgraded to a 9406-170 that he got on the cheap. “But soon I moved it to a 9406-820,” he says. “Numbers of user profiles was some 1,500 then. Since 2010 as I moved my company, the number of new users a day jumped over 25, so that was the point of no return.”

Today, PUB400 is running on a dedicated Power9 machine equipped with 64 GB RAM (which has access to up to 128 GB). The operating system is up-to-date at IBM i 7.5. Storage is handled via SAN, so there is lots of room for everyone. There’s plenty of CPU power to handle the load, Scherer says. “Except for some people on the Internet scanning systems,” he says. “Each SSH connect creates a job.”

While the hardware itself has changed over the years, the basic principles underlying the site have not. Scherer doesn’t monitor what people do on PUB400, but he reminds them that there is no technical support and there are no backups. If people want to run production IBM i workloads, he encourages them to sign up for a paid account on Powerbunker, the private IBM i cloud hosted by Scherer’s company, RZKH.

Community Involvement

While it’s not the only free IBM i resource on the Web, PUB400 is far and away the most popular. When somebody needs to get access to an IBM i command line, PUB400 is often the first recommendation.

The folks at IBM i change management software Remain Software aren’t shy about telling people where to go to try out their free tool, MiWorkplace, a lightweight and free browser-based editor for IBM i.

“You get a fully functional version of MiWorkplace with a preconfigured connection to the one and only public IBM i server PUB400.com,” the company says. “There are no excuses anymore why you can’t learn something new on IBM i. It is free!”

Nick Litten, an IBM i trainer, also recommends PUB400 to anybody who wants to learn IBM i. “I think it’s a great learning environment, to play with the most advanced business hardware,” he says on his website.

Looking forward, Scherer says he would like to expand PUB400, which hosts about 200 users on any given day. “There is some need for more services and tools to be provided, but as I do not get any discount or extra licenses from IBM, there is not much I can do,” he says. “Except ask tool vendors to have a free version, which I can include.”

When asked to reflect on his work with PUB400, Scherer, who is an IBM Champion for Power, provided this response:

“I learned a lot about security. I am proud the system is still up and running, and I get a lot of response of people who were able to get in touch with AS/400, err, IBM i programming. For some of them, it helped starting their career.”

The IBM i community certainly owes a debt of gratitude to Scherer for starting PUB400 nearly a quarter century ago. It’s not only a great resource for helping newcomers learn how to work with the system, but PUB400 is a legacy in its own right.

You can sign up for your own free IBM i account at PUB400.com.