Add support for TN3270

[blackbit42]

Hi @jquast

Have you ever looked at TN3270? Could you imagine to add support for it? Relevant RFCs are:

TN3270 Current Practices https://datatracker.ietf.org/doc/html/rfc1576 Jan 1994

TN3270 Extensions for LUname and Printer Selection https://datatracker.ietf.org/doc/html/rfc1646 Jul 1994

TN3270 Enhancements https://datatracker.ietf.org/doc/html/rfc2355 Jun 1998

TN3270E Service Location and Session Balancing https://datatracker.ietf.org/doc/html/rfc3049 Jan 2001

There are a few projects floating around that implement TN3270 servers in various languages, including python, though they all are rather nonchalant regarding telnet negotiation and focus on the application part. It would be great to do TN3270 by the book.

[jquast]

Hello @blackbit42, yes I was interested in TN3270, I did read those RFC's years ago when I implemented the others, I think I tried to implement some of it but later removed them, because I couldn't test it. I don't have any IBM servers clients to test with, this stuff is all commercial and costly.

If somebody suggests a PR that they've tested I'd certainly accept it.

[blackbit42]

Testing is easy with http://x3270.bgp.nu/ actually.

[jquast]

and which open source IBM server would I test it with?

[blackbit42]

Oh, for client connections you mean. I am not aware of any open source implementations by IBM or any other big brand vendor. There are mainframe OS images on archive.org that have been used successfully to run TN3270 servers. I am not going to advice using them though. There are also quite a number of publicly accessible servers on the internet.

x tammvs1.tamu.edu 992 TLS
x tammvst.tamu.edu 992 TLS TN3270E cert name mismatch
x teague-tammvs1.tamu.edu TLS TN3270E cert name mismatch
x 174.47.13.112 23 plain
x 65.196.87.141 23 plain TN3270E
x 47.19.64.73 23 plain TN3270E
x 47.19.64.74 23 plain TN3270E
x 80-122.206-83.static-ip.oleane.fr plain TN3270E
x vm.se.lsoft.com plain TN3270E
x 81.80.140.164 plain TN3270E <error message>
x 173-165-108-185-Illinois.hfc.comcastbusiness.net plain TN3270E
x ecommsvr.csclogic.com plain TN3270E
x 199.190.128.4 plain TN3270E
x 172-126-122-51.lightspeed.rlghnc.sbcglobal.net plain TN3270E
x 47.19.64.74 plain TN3270E
x IVY.UMIS.UPENN.EDU 992 TLS TN3270E
x IVYTEST.UMIS.UPENN.EDU 992 TLS TN3270E
x iron.umis.upenn.edu 992 TLS TN3270E
x 192.86.32.17 623 plain TN3270E
? ace.amadeus.net 992 TLS
x 77.92.104.14 623 plain
x 192.86.32.153 623 plain
x ctrek.dal-ebis.ihost.com 623 plain
x mntn.state.mn.us 2443 TLS TN3270E

But I guess you are looking for something else.