I am new to Linux. I want to switch to root user from a script file without prompting for password. I am writing this line
echo 'password' | sudo -S su
above runs nicely but does not change user to root user. I have seen that -S does not change user so i tried -i as well but then it prompts for password. Please help
I am trying to automate setting up a user on centos as part of my script. Here is what i am doing:-
/usr/sbin/useradd my-user
/usr/bin/passwd my-user
You will be be prompted to enter password for the my-user user
Now is there a way to skip the second command so that there is no manual prompt, so that i can have something in the script to auto create my-user on centos without needing to manually enter the password
You can change password programmatically, using:
echo -e "xyz\nxyz\n" | /usr/bin/passwd my-user
You can use chpasswd command with echo. Here is a simple example
/bin/echo my-user:password | /usr/sbin/chpasswd
i am doing automation the process by bat file.
putty.exe -ssh bhavepatel#10.10.178.140 -pw Winter34! -m C:\Users\BHAVEPATEL\Desktop\tel\tel.txt -t
In tel.txt file , i want to change the directory ans switch the user.Please see below code in tel.txt file
cd /apps/denodo/bin
sudo -su denodo bash; /bin/bash
Putty prompt with pwd when i swith the user to denodo. How can i pass the password input to bat file?
You cannot. Not in an interactive session.
See How to pass the password to su/sudo/ssh without overriding the TTY?
All you can do is to configure sudo not to ask for a password at all. That's the only legitimate approach. To admin that you are actually logging in without typing a password. Instead of secretly automating password typing.
See How to avoid prompt password for sudo?
I want to change the user in one command line with su
echo password | su user
But this is not working.
Is there a other possibility?
best wishes
First of all: Ask yourself whether it is really necessary for a script to know the password. sudo and SE-Linux usually give you plenty of options to avoid entering passwords.
This being said, su opens its controlling terminal to read the password, not stdin. You can use sudo with the -S option to read the password from stdin.
From sudo's manual:
-S
The -S (stdin) option causes sudo to read the password from the standard input instead of the terminal device. The password must be followed by a newline character.
Do the folowing ..
passwd root
it will ask you for a new password
put it and then you log as administrator and do what you want
We have a number of Red Hat linux servers in our IT environment. I am being asked by my team members to write a script (preferably shell script) to change a user's password on each one of those in a single go, using SSH.
I have tried to find a solution but many of the scripts I found are using Expect. We do not have Expect installed on our servers and the system admins have refused to let us install it. Also, the users do not have root access so passwd --stdin or chpasswd cannot be used.
Is there any way a script can be written so that a user can run it and change the password of only his own user on all the servers in a list?
The remote machine(s) do not need expect installed. You can install expect on a local workstation or VM (virtualbox) or whichever *nix box, and write a wrapper that calls this .ex (expect) script (there may be small changes from distro to distro, this tested on CentOS 5/6):
#!/usr/bin/expect -f
# wrapper to make passwd(1) be non-interactive
# username is passed as 1st arg, passwd as 2nd
set username [lindex $argv 0]
set password [lindex $argv 1]
set serverid [lindex $argv 2]
set newpassword [lindex $argv 3]
spawn ssh $serverid passwd
expect "assword:"
send "$password\r"
expect "UNIX password:"
send "$password\r"
expect "password:"
send "$newpassword\r"
expect "password:"
send "$newpassword\r"
expect eof
You do not need root access to use passwd.
This shoud work just fine.
passwd <<EOF
old password
new password
new password
EOF
You should try pssh (parallel ssh at the same time).
cat>~/ssh-hosts<<EOF
user100#host-foo
user200#host-bar
user848#host-qux
EOF
pssh -h ~/pssh-hosts 'printf "%s\n" old_pass new_pass new_pass | passwd'
Building on squashbuff's example, I tried the following, which worked well for me:
#!/bin/bash
for server in `cat hostlist`; do
echo $server;
ssh username#$server 'passwd <<EOF
old_password
new_password
new_password
EOF';
done
Security wise, Could be improved to take input without echoing to the screen OR saving the plaintext to disk.
echo "name:password" | chpasswd
Another possibility: change it manually on one server. Get the encrypted password out of /etc/shadow. Now, do something like this:
for host in $HOST_LIST; do
ssh $host "passwd -p 'encrypted_passwd' user"
done
Of course, 'encrypted_passwd" is what you got out of /etc/shadow where you manually changed the password. And $HOST_LIST is a list of hosts where you want the password changed. That could be created simply with:
export HOST_LIST="server1 server2 server15 server67"
Or perhaps with a file (as others have suggested):
export HOST_LIST=`cat host_list.txt`
Where the file "host_list.txt" has a list of all the systems where you want the password changed.
Edit: if your version of passwd doesn't support the -p option, you might have the 'usermod' program available. The example above remains the same, simply replace 'passwd' with 'usermod'.
Furthermore, you might consider the useful tool pdsh, which would simplify the above example to something like this:
echo $HOST_LIST | pdsh -Rssh -w- "usermod -p 'encrypted_passwd' user"
One last "gotcha" to look out for: the encrypted password likely contains the dollar sign character ('$') as a field separator. You'll probably have to escape those in your for loop or pdsh command (i.e. "$" becomes "\$").
Install sshpass on any of the server from where you want to execute the script.
yum -y install sshpass
Prepare a text file in which you have to pass details like Host, User Name, Password and Port. (Based on your requirement).
192.168.1.2|sachin|dddddd|22
Prepare a script file using below details.
#!/bin/bash
FILE=/tmp/ipaddress.txt
MyServer=""
MyUser=""
MyPassword=""
MyPort=""
exec 3<&0
exec 0<$FILE
while read line
do
MyServer=$(echo $line | cut -d'|' -f1)
MyUser=$(echo $line | cut -d'|' -f2)
MyPassword=$(echo $line | cut -d'|' -f3)
MyPort=$(echo $line | cut -d'|' -f4)
HOST=$MyServer
USR=$MyUser
PASS=$MyPassword
sshpass -p $PASS ssh -p $MyPort -o StrictHostKeychecking=no $USR#$HOST \
-T "echo 'sachin#patel' | passwd --stdin root" \
< /dev/null | tee -a output.log
done
exec 0<&3
An alternative you may want to present to your peers would be to have them use password-less authentication. They'd generate a public/private key pair and register their public key in the ~/.ssh/authorized_keys file on each of the servers they log into.
Can you use Perl?
Here there is an script that changes the password in a set of hosts.
If requires some Perl modules (Net::OpenSSH::Parallel, Expect and their dependencies) installed on the local machine running the script but nothing on the remote servers where the password has to be changed.
Have you tried App::Unix::RPasswd
The passmass script (man page) that comes with Expect doesn't require Expect to be installed on the remote machines.
I just implemented a small tool that changes password for many users/hosts at once. It's java based application so it works on both Windows and Linux. It's free, enjoy :)
Thought I should put my solution in an answer field - not sure if this should be a part of the question..
OK, I have put together a partially working solution using Dennis' suggestion.
servers.txt looks like:
server1
server2
server3
.
.
.
I am using:
for server in `cat servers.txt`; do
ssh $server -l user 'passwd <<EOF
old_pass
new_pass
new_pass
EOF';
done
This produces:
user#server1's password: **<Type password manually>**
(current) UNIX password: New UNIX password: Retype new UNIX password: Changing password for user user.
Changing password for user
passwd: all authentication tokens updated successfully.
user#server2's password: **<Type password manually>**
(current) UNIX password: New UNIX password: Retype new UNIX password: Changing password for user user.
Changing password for user
passwd: all authentication tokens updated successfully.
So here, I still need to type my old password once for each server. Can this be avoided?
If you have ssh, why have passwords in the first place? Push the user's public ssh key to all the servers they're authorized to use and be done with it. This also lets you easily grant and revoke access all you want.
At a previous $dayjob, where we had literally tens of thousands of servers, they had a database of which engineers were allowed on which servers, and the installation of ssh keys was an automated process. Almost NOBODY had a password on ANY machine.
echo -e "wakka2\nwakka2\n" | passwd root
cat /tmp/passwords | ssh $server sudo chpasswd -e
if the password is encrypted, or
cat /tmp/passwords | ssh $server sudo chpasswd
if the password is not encrypted.
/tmp/passwords should have format of "user:password"
The real question is why were they not using some sort of name services? NIS/Yellow Pages or LDAP and you're not having to manually change passwords across a bunch of servers. A user changes their password once and it's done across the domain master.