Telnet session: cannot disable BINARY negotiation; login fails against Ultrix telnetd (Enter key handling)

Telnet session: cannot disable BINARY negotiation; login fails against Ultrix telnetd (Enter key handling)

1 vote

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Product: Remote Desktop Manager (Windows), version 2026.3.8.0 64 bit (PreJIT)
Session type: Telnet, embedded (tabbed)
Server: DEC Ultrix 4.5 (VAX) telnetd

Problem Login through the RDM Telnet session always fails, or hangs, on Ultrix telnetd. The same server works fine from PuTTY in Telnet mode.

What a packet capture shows
- RDM proposes IAC WILL BINARY and IAC DO BINARY, and the server accepts both.
- With "Return key sends a new line instead of a carriage return" ticked, Enter is sent as CR LF (0d 0a). With it unticked, Enter is sent as a bare CR (0d).
- A bare CR leaves login stuck after the username: no Password: prompt.
- CR LF reaches the Password: prompt, but login then reports "Login incorrect" with the correct password.

Analysis
Once BINARY is active, BSD-derived telnetd (including Ultrix) turns off CR/LF translation. The CR in CR LF then stays inside the line, so login receives "username<CR>" and "password<CR>" instead of the clean strings. The server also stops adding CRs on output. This is consistent with what the capture shows. I have not found an option to turn off BINARY, or to send LF only for Enter. Remapping Enter to another CTRL-J in the Keyboard tab had no effect on the bytes sent.

Requests
1. A per-entry option to disable telnet BINARY negotiation (or make it opt-in).
2. Or an Enter-key option to send LF only, or CR NUL, that is honoured for keyboard input and for the autologin (User/Password prompt string) feature.
3. Ensure the Keyboard tab key map is applied to Enter in Telnet sessions.

All Comments (1)

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Hello,

Thank you for the request, I've opened an internal ticket and we'll take a look at what we can do.

Regards,

Hubert Mireault