Subj : Solved issue with SyncTerm after up/download on my BBS
To   : Digital Man
From : AKAcastor
Date : Wed Apr 17 2024 02:03 pm

 DM> ASCII mode is the default, so if there's no mention of 
 DM> "BINARY TX" in either direction during initial 
 DM> conneciton, then ASCII mode was successfully 
 DM> negotiated. As I recall, SyncTERM doesn't initate any 
 DM> explicit Telnet commands regarding BINARY TX upon 
 DM> initial connection, so unless the Telnet server does 
 DM> (e.g. sends "DONT BINARY TX"), then SyncTERM is correct 
 DM> in assuming ASCII mode.

The server is negotiating binary mode, as well as character mode, on connection.  I imagine every BBS is at least negotiating character mode.  The handful that I checked when I was initially setting my system up were negotiating character mode and binary on initial connection.

 > SyncTerm is incorrectly 'returning' to ASCII mode after
 > file transfers.

 DM> SyncTERM *attempts* to return to ASCII mode, but the 
 DM> server can definitely NAK the messages (as you've discovered).

Sure, but that's kind of hacky.  hehe ;)

 DM> If the Telnet server explicitly requested the client to 
 DM> be in BINARY TX mode during initial connection, then I 
 DM> suppose it could be considered "incorrect" for SyncTERM 
 DM> to want to *return* to a mode it wasn't already in. But 
 DM> I'm not clear that's the case since I didn't see a log 
 DM> of telnet commands sent and received from the start of 
 DM> the connection.

Yes, that's what happened - telnet server negotiated binary during initial connection.

I connected to Roon's BBS to compare the behaviour (also running Maximus, but in OS/2 not DOSBox) and in the SyncTerm log I see similar behaviour by SyncTerm.  On connection, the BBS negotiates binary mode, after a file transfer SyncTerm requests ASCII mode, and in this case the server complies.  If a second file transfer is attempted, SyncTerm will request a switch to binary mode and then after the transfer back to ASCII mode again.

 > I don't think I see a pressing need for my system to support ASCII mode
 > telnet as I expect any client should support binary (maybe there's
 > some edge cases in niche implementations or a benefit of ASCII mode that I
 > am missing?)

 DM> I guess you'll find out. :-)

Sounds exciting, doesn't it!  haha

Given that my BBS (and others I connect to, for example those using Vmodem in OS/2) works well in binary mode from first connection until file transfer, I don't see a reason for supporting ASCII mode between file transfers.

I mean there is one reason to support it - for the sake of completely supporting the telnet protocol.  But I feel like in this case that's only a matter of principle.

 DM> k, cool. I might play with connecting to your BBS and 
 DM> see what I find wrt its telnet server and comment further.... or not. :-)

I would appreciate any insight!  You have a lot more experience with the protocol and what different clients/servers may expect in the real world than probably anybody here.


Chris/akacastor

--- Maximus 3.01
 * Origin: Another Millennium - Canada - another.tel (21:1/162)

.