2

I need to run any "remote shell daemon" (ssh, telnet, netcat, socat... I don't mind) as non-root user. The remote shell should provide tab-completion and I want to be able to browse history using arrows.

I am currently using a netcat-based solution, but I loose tab-completion and I am unable to browse history using arrows

On server side :

# Run the "remote shell daemon"
$ mkfifo fifo
$ nc -l 2000 <fifo | /bin/bash &> fifo
$ rm fifo

On client side :

# Connect to the remote shell
$ nc $REMOTE_ADDR 2000

Adding the -i or -l argument to bash does not help.

  • If you use ssh and your remote shell is properly configured then you should have tab-completion and history browsing. At least I have when I login to my server using Ubuntu 12.04 on both machines. – Anthon Apr 18 '13 at 12:42
  • I need to run a "remote shell" daemon as non-root user. Sshd typically runs as root. – Xion345 Apr 18 '13 at 12:43
  • As long as the config files and the keys are owned by the user running sshd, and you use a port number > 1024 you don't need to run sshd as root. – Anthon Apr 18 '13 at 13:05
  • Why do you need to run the daemon as a regular user? What are you trying to achieve? – terdon Apr 18 '13 at 13:32
  • 1
    @terdon : I use a computing grid and I don't have a shell access to all nodes of the grid. The only thing I can do is submit scripts to the system (it's Grid Engine), and they will be scheduled on the node I specified. I would like to write a script that would allow me to have a shell access to a node of the grid. – Xion345 Apr 18 '13 at 13:47
3

socat(1) could be of some help.

From http://stuff.mit.edu/afs/sipb/machine/penguin-lust/src/socat-1.7.1.2/EXAMPLES:

// poor mans 'telnetd' replacement
# socat tcp-l:2023,reuseaddr,fork exec:/bin/login,pty,setsid,setpgid,stderr,ctty
// and here an appropriate client:
$ socat -,raw,echo=0 tcp:172.16.181.130:2023

Here, the example uses "login" which obviously requires a root access but I succesfully tested with /bin/zsh. This implies that security is not a problem... Otherwise, as they say in the webpage where I found out this tip, you could use a client authentication with SSL to make sure only you can actually log in.

1

Tab completion with netcat:

- stty   : change and print terminal line settings  
- echo   : echo input characters  
- icanon : enable erase, kill, werase, and rprnt special characters
- sane   : Revert back default terminal line setting

Command :

bash-4.3# stty -echo -icanon && nc ... && stty sane

Example :

stty -echo -icanon && nc 0 5000 && stty sane Note : 5000 is the port number

For more Info you can refer to linux man page :

Linux man Page - stty

Linux man Page - netcat

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