Solved

Telnet - disabling the echo

Posted on 2002-07-28
5
490 Views
Last Modified: 2010-04-21
Hi

I'm creating a Telnet like programm.
I want to know, how can I send data to the remote telnet (the telnet to connect to me), so a string will not echo (such as in password scanarios).
I can't find where in the RFC it's defined.

Can anyone help ?

Liron
0
Comment
Question by:lirong
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
5 Comments
 
LVL 51

Expert Comment

by:ahoffmann
ID: 7183769
man ioctl
man stty
0
 
LVL 14

Expert Comment

by:chris_calabrese
ID: 7185567
As for the RFC's, they're mum because it's not a protocol issue, but rather an issue for the host the server is running on (whether the OS thinks it should do character echo or not).
0
 

Expert Comment

by:skatethere
ID: 7267200
You've probably figured this out by now, but if not...

Most telnet client/servers negotiate two options that control the state of character echo: WILL ECHO and WILL SUPPRESS GO AHEAD.

These two settings specify that each character should be sent from the client to the server, echoed by the server, and displayed on the client when the echo is received.  This reverses what the original RFC854 says about all echos being local and all transmissions been line-at-a-time.

This is done in order to allow the server to control whether or not a character is echoed (and to improve interactivity).  With these settings in place, all a server needs to do to hide a password is to not echo it.

Practially speaking, if you are running a shell on your server to interact with the client, you would call 'stty -echo' to effect this change, and then 'stty echo' to reestablish echo.

In a program, look at the termio(7) ioctl(2).

  --kirby
0
 
LVL 21

Expert Comment

by:tfewster
ID: 7921715
No comment has been added lately, so it's time to clean up this Topic Area.
I will leave a recommendation for this question in the Cleanup topic area as follows:

- PAQ, no points refunded

Please leave any comments here within the next 7 days

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER !

tfewster
Cleanup Volunteer
0
 

Accepted Solution

by:
SpideyMod earned 0 total points
ID: 7967308
0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When you do backups in the Solaris Operating System, the file system must be inactive. Otherwise, the output may be inconsistent. A file system is inactive when it's unmounted or it's write-locked by the operating system. Although the fssnap utility…
In tuning file systems on the Solaris Operating System, changing some parameters of a file system usually destroys the data on it. For instance, changing the cache segment block size in the volume of a T3 requires that you delete the existing volu…
Learn how to find files with the shell using the find and locate commands. Use locate to find a needle in a haystack.: With locate, check if the file still exists.: Use find to get the actual location of the file.:
In a previous video, we went over how to export a DynamoDB table into Amazon S3.  In this video, we show how to load the export from S3 into a DynamoDB table.
Suggested Courses

617 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question