SSH Command – Why Does This SSH Command Not Work?

piperootsshsudo

I'm trying to do the following but it's not quite right.

cat ~/Desktop/blah.png | ssh -t -t trusktr@50.116.4.56 "cat | sudo -i 'cat | /path/to/blah.png'"

I have my public ssh key in the trusktr@50.116.4.56 user's .ssh folder, so no initial password is needed. When the sudo -i command finally starts, it prompts me for the root password, but immediately fails as if I had pressed enter but I didn't even touch the keyboard. I have a feeling maybe the cat command is being catted into the password prompt. The output looks like this:

trusktr@LENOVO-PC ~
$ cat ~/Desktop/win-8.1-missing-lockscreen-setting.png | ssh -t -t trusktr@50.116.4.56 "cat | sudo -i 'cat > /srv/http/default/htdocs/~/img/win-8.1-missing-lockscreen-setting.png'"
tcgetattr: Not a character device
[sudo] password for root:
You type like i drive.
[sudo] password for root:
Your mind just hasn't been the same since the electro-shock, has it?
[sudo] password for root:
Maybe if you used more than just two fingers...
sudo: 3 incorrect password attempts
Connection to 50.116.4.56 closed.

I don't have direct ssh access through the root user, only through a normal user with access to sudo using the root password.

How might I cat the image through ssh, through the non-root user, into the root location all in a single command?

Best Answer

It does not work because you are cating blah.png into sudo, which is not a valid password.

This should combine the needed commands onto one line:

scp ~/Desktop/blah.png trusktr@50.116.4.56:~/ && ssh -t -t trusktr@50.116.4.56 "sudo cp ~/blah.png /path/to/blah.png && rm ~/blah.png"

Related Solutions

Ssh – Obtain sudo priviledge without sudo password

In the past this would have been doable without Alice’s help, since sudo’s tokens were valid across terminal sessions: Bob could just wait for Alice to authenticate with sudo, then use sudo himself without having to enter a password.

Even with per-terminal tokens, obtaining Alice’s password is relatively easy in the scenario described here, as long as Alice doesn’t check her environment thoroughly all the time:

using Alice’s account, create ~/.bin/sudo with something like

#!/bin/sh
if [ $# = 0 ]; then exec /usr/bin/sudo; fi
if [ ! -f ~/.bin/alices-password ]; then
  echo -n "[sudo] password for $USER: "
  read -s password
  echo
  echo ${password} > ~/.bin/alices-password
  sleep 2
  echo "Sorry, try again."
  /usr/bin/sudo -k
fi
exec /usr/bin/sudo "$@"

add ~/.bin to the path, in the appropriate rc-file depending on which shell Alice uses;
wait for Alice to use sudo in a shell which has noticed the presence of ~/.bin/sudo...

Bob can wait for a password to appear in ~/.bin/alices-password and try it himself before disabling the special variant (doing that in an unobtrusive way is left as an exercise for the reader — remember that the shell caches paths...).

There are a few subtleties in the script above, in particular sudo -k which ensures that “Sorry, try again.” will actually be followed by sudo asking for a password. The script could be improved further, that’s another exercise for the reader!

As you might imagine, this isn’t the only approach...

Ssh login as user and change to root, without sudo

Perhaps somewhat off topic but this could be achieved with Python and the paramiko module:

#!/usr/bin/python2
import time
import paramiko

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect('127.0.0.1', port=22, username='user', password='pass')

stdin, stdout, stderr = ssh.exec_command('su')
time.sleep(0.1) # some enviroment maybe need this.
stdin.write('root_password_goes_here\n')

[ add extra code here to execute a command ]

stdin.flush()
print (stdout.readlines())
ssh.close()

It should be noted that storing passwords in script generally is a bad idea from a security perspective. Make sure you have proper permissions set to the script (e.g. chmod 740)

Best Answer

Related Solutions

Ssh – Obtain sudo priviledge without sudo password

Ssh login as user and change to root, without sudo

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