Problem: Keyboard Input Echoed Back to Serial Terminal using PuTTY to Linux System

I enabled the serial console on a Debian Linux system. I used PuTTY to connect to the serial console. However, I encountered a problem, i.e., any keyboard inputs were echoed back to the serial console. The following screen shot perhaps explains the problem, e.g., when I enter user name, the user name is echoed back again, and when I enter the password, by default, the terminal shouldn't show anything, but it echoes it back.

 

A Stack Overflow thread discusses a similar problem, and I linked it below,

•  PuTTY serial communication

The thread led me to experimenting the terminal setting in PuTTY. The default setting of the "Line discipline options" is "Auto" for "Local echo", and "Auto" for "Local line editing" shown in the screen capture below. When using these settings, I encountered the problem I described in the above.

My fiddling with the settings tells me that the solution is to check "Force off"  for "Local echo", and "Force off" for "Local line editing" shown in the screen shot below,

Having made the setting changes, I saw that the problem went away. Well, we can see it from the screen shot below,