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https://issues.apache.org/jira/browse/GUACAMOLE-269?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16369504#comment-16369504
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Nick Couchman commented on GUACAMOLE-269:
-----------------------------------------

So, there's something a little strange here that I'm having a hard time 
figuring out.  It looks like, in most cases, the information about the 
backspace key and/or stty erase is automatically passed through from the SSH 
client to the server.  I've yet to figure out exactly how this works, but 
here's what I've done:
- On my Linux system (OpenSuSE, XFCE, etc.), SSH into an AIX machine.  
Backspace key works as expected, and "stty -a" reveals that erase=^?.  I can 
also do the "Ctrl-V + Backspace" key combo to print out what Backspace is 
sending.
- On my Windows system (Windows 10, PuTTY), open a SSH system into the same AIX 
machine with the default settings.  Backspace key, again, works as expected, 
"stty -a" shows erase=^?, and the magic combo shows that Backspace is sending 
that.
- On my Windows system, change the PuTTY settings such that Backspace sends 
Ctrl-H instead of Ctrl-? (the default), then open the SSH session to the same 
AIX host.  Backspace works as expected, but "stty -a" shows erase=^h, and the 
magic key code shows Backspace is sending ^h.
- In Guacamole, connect to the same AIX system, and Backspace just results in 
^? being displayed repeatedly across the screen.  "stty -a" shows erase=^h, but 
Backspace is not sending that.
- In Guacamole, connect to a Linux system, and Backspace works as it should, 
"stty -a" shows erase=^?, and that's what Backspace is sending.

>From all of this testing, I gather that there is something that both either 
>the Linux terminal and/or SSH client, and the Windows PuTTY client, are 
>providing to the SSH server on AIX that guides how it sets up the stty info, 
>and that Guacamole (libssh2) is not providing this information, or is 
>providing the wrong information.  At first I thought maybe it was the terminal 
>name/type that was being provided, since "linux" is what Guacamole sends, but 
>is not a known terminal type on AIX, so I tweaked the Guacamole client/server 
>code to allow this to be configurable, and tried several values (linux, vt100, 
>vt220, xterm, and xterm-256color), but this did not change the behavior on AIX 
>at all - it still defaults to ^h as the erase character, no matter what value 
>the terminal is set to.

So, not sure what's going on, here - could be the version of libssh2 I'm using, 
I suppose, or that there's something that the Guacamole calls to libssh are not 
configuring properly before opening the connection.  Not sure.  Any hints would 
be appreciated.

> Add support for alternative backspace/delete control codes
> ----------------------------------------------------------
>
>                 Key: GUACAMOLE-269
>                 URL: https://issues.apache.org/jira/browse/GUACAMOLE-269
>             Project: Guacamole
>          Issue Type: Improvement
>          Components: SSH, Telnet, Terminal
>            Reporter: Michael Jumper
>            Assignee: Nick Couchman
>            Priority: Minor
>
> {panel:bgColor=#FFFFEE}
> *The description of this issue was copied from 
> [GUAC-1003|https://glyptodon.org/jira/browse/GUAC-1003], an issue in the JIRA 
> instance used by the Guacamole project prior to its acceptance into the 
> Apache Incubator.*
> Comments, attachments, related issues, and history from prior to acceptance 
> *have not been copied* and can be found instead at the original issue.
> {panel}
> On some devices, such as Comware devices, the backspace and delete keys will 
> not work, as such devices use Ctrl-H or Ctrl-D for these respectively. 
> Guacamole should provide configuration options for SSH and telnet, such that 
> different control codes can be used for backspace/delete for the sake of 
> compatibility.



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