Linux – Ubuntu 10.04 using ssh without entering the password

bashlinuxpasswordsssh

I know questions like this have been asked before, and I have read them all (that I found).

The problem I have is that we have an embedded linux device that we can log into for debug purposes by doing the following:

ssh root@name

Then the password is anything (I usually just hit enter). I don't want to change anything on the embedded device/linux. But I do want to be able to (as part of my script) ssh into it.

My research has shown me that the following can be used (this is copied from another post):

#!/usr/bin/expect -f
spawn ssh user@my.server.com
expect "assword:"
send "mypassword\r"
interact

However with my version of Ubuntu (10.04) I don't have spawn or send commands. I was able to install the "expect" command with sudo apt-get install expect.

Does anyone have a solution? is it possible to install these commands, or is there another way to ssh and get past the "password" step?

Thanks 🙂

————- EDIT —————–

I think I am starting to understand the issue I am having. I have a script that starts with:

#!/bin/bash

Then later I am trying to do:

spawn ssh user@my.server.com
expect "assword:"
send "mypassword\r"
interact

I did not realise that you needed explicitly the:

#!/usr/bin/expect -f

At the start of the script. so I have had to move my code into a seperate file which contains only and exactly:

#!/usr/bin/expect -f
spawn ssh user@my.server.com
expect "assword:"
send "mypassword\r"
interact

… sorry for the mis-understanding on my part, but people answers helped me to twig what I was doing. This is not quite ideal for me as I wanted to pass parameters in to open different ssh connections and I can't pass in parameters to this script starting with "expect -f"
🙁

Best Answer

I think you're trying to run your script as a shell script. After installing expect, run your script like this:

expect -f scrip.exp

If you can't install expect as a normal user, try installing its binaries in one of your directories in $HOME e.g. $HOME/opt/ and call expect from there, although it would depend on your system on how you could manipulate LD_LIBRARY_PATH to add another directory for searching dynamic libraries.

An example of embedded expect:

#!/bin/bash

USER=$1
SERVER=$2
PASSWORD=$3

expect <<EOF
spawn ssh "${USER}@${SERVER}"
expect "assword:"
send "${PASSWORD}\r"
interact
EOF

Run with

bash script.sh user server password

Related Solutions

Linux – ssh without password from a bash script

ssh -i selects a file from which the identity (private key) or public key authentication is read.

You could configure ssh to use it in your config for this host so you do not have to specify it.

Add to ~/.ssh/config (replace server.example.com with hostname or IP of your server):

Host server.example.com
    User username
    Hostname server.example.com
    PreferredAuthentications publickey,password
    IdentityFile ~/.ssh/id_rsa.pub

This config will make your connection to always try to use id_rsa.pub key and then fallback to password if key would not be available for some reason.

So now you should be able to use ssh <user>@<host> <command> with it automatically using your private key for authentication.

Linux – Send Password in ssh script

There are various possibilities. You can use expect script or simple sshpass, but the password will be written in the script itself so the user can read it from there (this is not a security).

In short:

sshpass -p password ssh user@host

The better solution is passwordless authentication using key pair.

In short, you will create a new key pair, store it in the server and incorporate it in your script:

ssh-keygen -t rsa -f key_file -P '' # prepare the key pair
ssh-copy-id user@host               # enter the password once
ssh -i key_file user@host           # logs in without password

Best Answer

Related Solutions

Linux – ssh without password from a bash script

Linux – Send Password in ssh script

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