How to make ssh receive the password from stdin

Question

How can you make SSH read the password from stdin, which it doesn't do by default?

Answer 1

Distilling this answer leaves a simple and generic script:

#!/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 whatver 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:

Answer 2

An old post reviving...

I found this one while looking for a solution to the exact same problem, I found something and I hope someone will one day find it useful:

1. Install ssh-askpass program (apt-get, yum ...)
2. Set the SSH_ASKPASS variable (export SSH_ASKPASS=/usr/bin/ssh-askpass)
3. From a terminal open a new ssh connection without an undefined TERMINAL variable (setsid ssh user@host)

This looks simple enough to be secure but did not check yet (just using in a local secure context).

Here we are.

Answer 3

FreeBSD mailing list recommends the expect library.

If you need a programmatic ssh login, you really ought to be using public key logins, however -- obviously there are a lot fewer security holes this way as compared to using an external library to pass a password through stdin.

Answer 4

based on this post you can do:

Create a command which open a ssh session using SSH_ASKPASS (seek SSH_ASKPASS on man ssh)

$ cat > ssh_session <<EOF
export SSH_ASKPASS="/path/to/script_returning_pass"
setsid ssh "your_user"@"your_host"
EOF

NOTE: To avoid ssh to try to ask on tty we use setsid

Create a script which returns your password (note echo "echo)

$ echo "echo your_ssh_password" > /path/to/script_returning_pass

Make them executable

$ chmod +x ssh_session
$ chmod +x /path/to/script_returning_pass

try it

$ ./ssh_session

Keep in mind that ssh stands for secure shell, and if you store your user, host and password in plain text files you are misleading the tool an creating a possible security gap

Answer 5

I'm not sure the reason you need this functionality but it seems you can get this behavior with ssh-keygen.

It allows you to login to a server without using a password by having a private RSA key on your computer and a public RSA key on the server.

http://www.linuxproblem.org/art_9.html

Answer 6

You can't with most SSH clients. You can work around it with by using SSH API's, like Paramiko for Python. Be careful not to overrule all security policies.