Shell Script for logging into a ssh server

Question

I tried writing a shell script which can do automatic login into a ssh server using password which is mentioned in the script. I have written the following code:

set timeout 30
/usr/bin/ssh -p 8484 root@172.31.72.103
expect 
{
   "root@172.31.72.103's password" 
   {
      send "password\r" 
   }
}

This code is not running properly, still it is asking for the password. Can somebody please help me in solving this

http://serverfault.com/questions/241588/how-to-automate-ssh-login-with-password — Ciro Santilli OurBigBook.com, Nov 30 '15 at 21:23

score 48 · Accepted Answer · answered Feb 07 '12 at 09:43

48

I once wrote an expect script to log in to a ssh server (like your case) and my script was something like this:

#!/usr/bin/expect

spawn ssh MyUserName@192.168.20.20
expect "password"
send "MyPassword\r"
interact

I think maybe the interact is missing in your script.

answered Feb 07 '12 at 09:43

saeedn

2,494
3
20
15

this is absolutely working fine for me and i am stuck in this place, the interact provides interactive terminal with prompt, but i am trying to automate further more steps like do cd and ls and read the contents of the file as well. Is it possible to do after interact? Please reply – Hansiemithun Aug 01 '18 at 14:57
@Hansie you can send an ls command after the login. For example after sending password, do an expect with the command prompt text (to make sure you are logged in), then send "ls\r". All of these goes before interact. – saeedn Aug 03 '18 at 00:09
the question was slightly incorrect and i am sorry after doing ls and read contents, i am able to print the same. But how to get that out of ssh session into a variable to access from local machine. ref: https://stackoverflow.com/questions/32341234/expect-script-return-value. But output is not working for me. My question posted: https://stackoverflow.com/questions/51628465/how-to-change-directory-in-shell-script/51637048?noredirect=1#comment90238913_51637048. I need file_list after exit to access from local command prompt – Hansiemithun Aug 03 '18 at 06:02
send "MyPassword\r" is not working @saeedn – Chaminda Bandara Jan 24 '21 at 04:09
this is not working for me on ubuntu – Jamshaid Jan 26 '21 at 07:50
If you get an /usr/bin/expect bad interpreter no such file or directory error, try installing expect with sudo apt install expect – Suda Aug 26 '21 at 02:46

score 35 · Answer 2 · edited Nov 11 '15 at 14:30

35

You're going about it the wrong way. What you want to do is generate a passwordless ssh-key pair and then (as long as the server supports RSA key authentication) you can get in without having to type a password for all. This is a security risk if your private key is stored somewhere that it could be stolen.

Follow these steps:

mkdir -p ~/.ssh
cd ~/.ssh
ssh-keygen -type dsa -i mysshkeys
Press Return when prompted for passphrase
Press Return a second time to confirm.

There will now be two files in your ~/.ssh directory, mysshkey.pub and mysshkey. mysshkey.pub is your public key, this one is safe to put on remote servers. mysshkey is your private passwordless key, it is not safe to put on remote servers (or somewhere someone else could get a copy).

On the server you wish to SSH into:

Login to the remote server
mkdir -p ~/.ssh
Copy and paste the contents of mysshkey.pub into ~/.ssh/authorized_keys
Make sure that ~/.ssh/authorized_keys is chmod'd to 600

Now, to put it into action on your local machine you run the following command:

ssh -i ~/.ssh/mysshkey <remote_server_ip>

And you will be logged in without being prompted for a password.

This is a much preferable method of managing automated logins as you don't end up hard-coding your password multiple places that need to be updated if you ever change it.

edited Nov 11 '15 at 14:30

Steven Linn

103

answered Feb 07 '12 at 07:38

synthesizerpatel

842

2

I would use RSA keys rather than DSA. But other than that, full agree. – glglgl Feb 07 '12 at 09:03
18

sometimes you cannot add keys to the remote host, eg network appliances. – Apr 13 '16 at 05:07
1

I tried this. ssh is still asking for a password. Do you specifically have to give an IP address? I tried it with both @ and just the domain name. – Jay Bienvenu Jun 20 '17 at 14:39
This command said too many arguments? (for step 3) – Joseph Astrahan Aug 08 '17 at 02:59
I had to change to ssh-keygen -t dsa and manually enter file location instead. – Joseph Astrahan Aug 08 '17 at 03:10
@JayBienvenu did you ever get it to work? – Joseph Astrahan Aug 08 '17 at 03:56
I finally got it to work. I was using digital ocean, trick is to go to settings in digitalocean found under your profile image upper right, click security, add the ssh key here, then you have to login as root@domainhere.com – Joseph Astrahan Aug 08 '17 at 04:03
I do prefer this method, but my company does not create home directories on the remote servers, so it's nice to have a script alternative. – bdetweiler Aug 08 '18 at 12:52

score 22 · Answer 3 · edited Jun 11 '15 at 00:53

On Debian-based distributions, the sshpass package provides an easier way of doing what you want. The package is available for many other popular distributions. You need to set it up first:

echo 'YourPassword' > passwordFile.txt
chmod 600 passwordFile.txt

Then invoke the SSH command from a script like this:

sshpass -f /path/to/passwordFile.txt /usr/bin/ssh -p 8484 root@172.31.72.103

This provides more flexibility, such as if you're using a different locale or need to change the password, than solutions using expect.

score 9 · Answer 4 · edited Jan 29 '18 at 19:10

9

you can use this:

sshpass -p 'yourpassword'  ssh user@ip

edited Jan 29 '18 at 19:10

terdon

242,166

answered Nov 23 '16 at 12:08

Behrooz Mohamadi nasab

103

score 8 · Answer 5 · edited Aug 17 '18 at 12:57

8

First install the sshPass sudo apt-get install sshpass

Then create an alias in .bashrc file as

alias sshLogin='sshpass -p <your ssh password> ssh username@remote_host'

Now reload your changed .bashrc file by source ~/.bashrc

You are now done.

Now you can run the ssh using the above created alias sshLogin in terminal.

edited Aug 17 '18 at 12:57

Anthony Giorgio

105
4

answered Nov 28 '16 at 08:42

bpathak

81
1
1

score 3 · Answer 6 · edited Jun 17 '18 at 02:17

3

All what you need it to create a hashed key and save it on your PC

Just type

ssh-keygen -t rsa -b 4096 # just press Enter till the end

then enter

ssh-copy-id <user>@<server>

then login normally using

ssh <user>@<server>

Now you don't need a password

Note: Saving your password in a plain text is dangerous

This method is creating a hashed value of your password using RSA with public key of length 4096 which is very secure.

edited Jun 17 '18 at 02:17

slm

369,824

answered Jun 16 '18 at 22:24

Mohammad Hizzani

131

1

This appears to be a repeat of this answer. – Chris Davies Jun 16 '18 at 22:40
1

#roaima Yes, but it algo suggests the incredibly useful ssh-copy-id command, which nobody else mentioned. I'm upvoting it for that. – Huw Walters Jun 01 '19 at 10:47

score 2 · Answer 7 · answered May 31 '18 at 19:48

As already described in other answers, I also use sshpass but I combine it with the read command to store my password in an temporary environment variable. This way my password is never written anywhere in clear. Here is the one line command I use:

read -s PASS; sshpass -p $PASS ssh <user>@<host adress>

After that you have to enter your password (nothing appears on the screen) and then pressing enter will open the connection.

score 1 · Answer 8 · answered Sep 15 '17 at 00:47

SSH Passwordless Login Using SSH Keygen in 5 Easy Steps:

Environment setup:

Step 1: Authentication SSH-Kegen Keys on – (192.168.0.12)
First login into server 192.168.0.12 with a user and generate a pair of public keys using following command.

Step 2: Create .ssh Directory on – 192.168.0.11
Use SSH from server 192.168.0.12 to connect server 192.168.0.11 to create .ssh directory under it, using following command.

Step 3: Upload Generated Public Keys to – 192.168.0.11
Use SSH from server 192.168.0.12 and upload new generated public key (id_rsa.pub) on server 192.168.0.11 under user's .ssh directory as a file name authorized_keys.

Step 4: Set Permissions on – 192.168.0.11
Due to different SSH versions on servers, we need to set permissions on .ssh directory and authorized_keys file.

Step 5: Login from 192.168.0.12 to 192.168.0.11 Server without Password
From now onwards we can log into 192.168.0.11 as sheena user from server 192.168.0.12 as tecmint user without password.

Thanks... this worked for me, except at step 4 I got a dramatic "warning": "UNPROTECTED PRIVATE KEY FILE! ... .../.ssh/id_rsa' are too open. ... private key will be ignored... bad permissions". I did chmod 700 id_rsa in directory .ssh in the local (client, i.e. 192.168.0.12 in your example) server: problem solved — mike rodent, Apr 21 '18 at 08:14

score 1 · Answer 9 · answered May 30 '18 at 18:37

I recently did this, this may help you:

sshpass -p 'password' username@ipaddress

if this doesn't work then you'll have to generate keys in the other machine you want to connect with

ssh-keygen

it will generate private and public keys and ask you for a location, leave at empty it will save the keys in .ssh folder by default it will ask you for passphrase, you can also leave it empty the go in .ssh folder and change the public key name to 'authorized_keys'

cd .ssh/
mv id_rsa.pub authorized_keys
useradd -d /home/username username

this will add user to list now go to home directory and give permission and restart sshd services

chmod 700 /home/username/.ssh
chmod 644 /home/username/.ssh/authorized_keys
chown root:root /home/dozee
sudo service sshd restart

now you will have to move the private key to the system at that location from where you are going to run the ssh command, then you can connect with

sshpass -p 'password' ssh -i id_rsa username@ip

if even that doesn't work then go in /etc/ssh open sshd_config with vim editor check if the pubkeyAuthenticatoin is turned to yes or not, if not change it to yes , restart the sshd services and then try it, it will definitely work.

score 1 · Answer 10 · edited Jan 12 '24 at 16:05

1

First argument is hostname and second is password.

     #!/usr/bin/expect
     set pass [lindex $argv 1]
     set host [lindex $argv 0]
     spawn ssh -t root@$host echo Hello
     expect "*assword: "
     send "$pass\n";
     interact

Execution:

./script.expect hostname "my!password?"

edited Jan 12 '24 at 16:05

glenn jackman

85,964

answered Feb 18 '19 at 11:12

Shivam Mehrotra

111

score 0 · Answer 11 · answered May 05 '20 at 23:21

0

Just use the appropriate option

ssh -o PreferredAuthentications=password user@remote.server.tld

You can also go the other way around and simply forbid using keys.

ssh -o PubkeyAuthentication=no user@remote.server.tld

answered May 05 '20 at 23:21

kaiser

103
5

score 0 · Answer 12 · edited Jan 12 '24 at 17:12

Purely bash answer

#!/bin/bash
[[ $1 =~ 'password:' ]] && cat || SSH_ASKPASS="$0" DISPLAY=nothing:0 exec setsid "$@"

Save it as pass, do a chmod +x pass and then use it like this:

echo mypass | pass ssh user@host ...

If its first argument contains password: then it passes its input to its output (cat) otherwise it launches whatever was presented after setting itself as the SSH_ASKPASS program.

When ssh encounters both SSH_ASKPASS AND DISPLAY set, it will launch the program referred to by SSH_ASKPASS, passing it the prompt user@host's password:

Shell Script for logging into a ssh server

12 Answers12

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