在远程服务器上使用 ssh 执行 sudo su 不起作用

Question

This seems to be a popular question on stackoverflow but nothing seems to be working for me

I will explain my problems first and then go the the solutions I have tried

What I need to do is to ssh to serverB from serverA . for this I have set up an rsa encryption on the servers and I can successfully ssh to serverB

I use

ssh user@hostname

Now I want execute certain commands on serverB . The first one is to switch to app user. For this I need to run sudo su - app command but I also want to provide the password in the same line so that it doesnt prompt for the password again.

So I have tried to first directly run sudo su - app command on serverB with password to test it out

I have tried the following

echo "password" | sudo su - app

sudo -S  <<< "password" su - app

echo "password" | sudo -S su - app

echo 'passowrd' | sudo 'su -c - app'

However none of the above solutions work for me.

The closest I could get was with

echo "password" | script -c "sudo su - app"

where it accepts the password and shows me

app@hostname [/app]
$

however when I run the command whoami it still shows me user instead of app . however when I directly run sudo su - app and the provide pass and then run whoami it gives me app

I am trying to run command with ssh like

ssh user@hostname -t 'echo "password" | script -c "sudo su - app"'

PS the user user doesnt have root access and also I cannot make use of any plugin as I don't have permission to do the same

My server is Redhat 6.2

I hope I could explain it properly. Looking for some answers that can help.

Sorry for my bad English. Thanks for help.

Answer 1

If we set up ssh using rsa key encryption then we don't need to use the password.

In order to enable ssh with public/private key I follow

1. Genrate the public/private ke y for user on serverA

    ssh-keygen -t rsa

2. Go to .ssh/id_rsa.pub file and copy the public key

3. Login to ServerB and then do sudo su - app to change to app user. Here in the file .ssh/authorized_key copy the public key.

4. Try ssh to serverB now from serverA like

   ssh app@hostnameServerB

It works without asking for a password.