Hanging and reset connections when not using direct tn5250 to AS/400

[PoC-dev]

Environment description

• tn5250j running on macOS 11.7.1 with AdoptOpenJDK-11.0.11+9,
• Issue both apparent with current 0.8.0-beta2, as well as former version 0.7.6.

Sorry if this gets a bit lengthy. I think I need to explain my setup, so there is an understanding about differences to "plain" tn5250 connections — which work fine with tn5250j.

I'm using MS SNA Server 2.0, and MS HIS 2000 as a protocol translator between LU7 over SNA DLC 802.2, and tn5250:

• because IP is a resource-intensive protocol. Using SNA to connect to my stone aged AS/400 (instead of tn5250 over IP) saves considerable CPU cycles when scrolling though screens,
• because I have additional, older machines with no LAN connection. I'm using SDLC over serial ports to integrate those into my SNA APPN network. See here for details.

MS SNA Server and HIS are running on distinct machines here. Both open up a TCP port on the respective local Windows machine. Connecting with a 5250 client to it triggers an APPC session to the respective machine being established.

TLS is implemented via stunnel, essentially a wrapper around openssl s_server. Example configuration:

[telnets-as400]
accept = :::2323
connect = mshis.local:2323

Protocol negotiation is entirely dynamic and just dependent on openssl s_server defaults.

Problem description

Connecting with TLS yields the signon screen. After pressing enter to actually sign on, the connection is ended. The emulator window states X - Disconnected.

Connecting without TLS yields the signon screen. After pressing enter to actually sign on, the signon screen is retained. Pressing enter again yields the keyboard locked indicator, while the signon screen is still being shown. Looking at wrkactjob doesn't show that user's job.

The issue is apparent with V4R5 on my 150, as well as V3R2 on my P03, and V2R3 on my P02. In addition, issue is also apparent with tn5250.exe 0.17.4 from Scott Klement.

I have not found how to create a log file about what tn5250j is doing. Receiving some advice here would enable me to possibly provide more information.

Probably issues #39 and #51 are related?

What works

So far I've been using Mocha tn5250 on my Mac to connect with and without TLS to MS HIS with with only minor issues: When running an application using the Session Services sub-function of the Dynamic Screen Manager. This gets automatically involved when running a C application utilizing stdio calls, or the similar I/O functions of REXX, the tn5250 session might hang.

Since other people might not have or a Mocha license (or don't want to pay the asked price for it), I wanted to give free emulators a try, so I could mention those on my Website.

Also I plan to expose some or all of my machines to the outside world via said TLS proxy. Since I want to have different sign on screen languages dependent on the APPC device name being used, it would be nice to get the described issue(s) resolved.