Change Passwords with SSH and Expect

A few years ago I was supporting a very diverse environment with Solaris, AIX, and Linux servers; some with password logins, public/private key authentication, and several with SecurID passwords. All accounts were local, passwords expired every three months, and the accounts locked after three failed logins — so you can imagine the mess this created if you didn’t go around every server at least every three months. After I’d accumulated about half a dozen passwords, I wrote an Expect script to login and change my password and wrapped it with a bash script to try every old password I had. Since some servers needed a SecurID number to login, the bash script would pause on those and prompt me for the token before continuing.

I’ve seen a few Expect scripts to change passwords, but none that can handle one-time tokens (like SecurID), expired passwords (changed before arriving at the prompt), and the variety of prompts to support Solaris, AIX, Linux, etc. This morning I spent a some time cleaning up and streamlining the code, but I’m sure it can be improved and optimized even more. If you use this code, and find ways to improve it, please let me know in the comments below and I’ll update the script for everyone’s benefit.

The script is also available on GitHub here: https://github.com/jsmoriss/sshchpwd


#!/usr/bin/expect -f
#
# /usr/local/bin/sshchpwd.exp
#
# Expect script to change login passwords using SSH, with support for one-time
# tokens (like SecurID), expired passwords (changed before arriving at the
# prompt), on Solaris, AIX, Linux, etc.
#
# License: GPLv3
# License URI: http://www.gnu.org/licenses/gpl.txt
#
# Copyright 2012-2016 Jean-Sebastien Morisset (https://surniaulula.com/)
#
# Example:
#
#	$ export OLD_PASSWORD="oldpwd"
#	$ export NEW_PASSWORD="newpwd"
#	$ ./sshchpwd {server} {port} {token}
#
# The {port} and {token} command-line parameters are optional. If the server
# uses SecurID (or another one-time password), enter it on the command-line as
# the third parameter.

set timeout 15
set server [lindex $argv 0]
set port [lindex $argv 1]
set tokpwd [lindex $argv 2]
set oldpwd $env(OLD_PASSWORD)
set newpwd $env(NEW_PASSWORD)
set prompt "\[>%\\$#\] "

if { $port == "" }  { set port "22" }
if { $tokpwd == "" }  { set tokpwd $oldpwd }

send_user "connecting to $server on port $port\n"
spawn ssh -p $port $server

# Mission of this first expect - get to the shell command prompt. If the
# password is expired and we have to change it before getting to the prompt,
# then exit 0 (success).  

expect {
	"(yes/no)? " { 
		send_user " (detected unknown host key - accepting)\n"
		send "yes\n"
		send_user " (continuing expect loop)\n"
		exp_continue
	}
	"assword:" { 
		send_user " (detected password login prompt - possibly token)\n"
		send "$tokpwd\n" 
		expect {
			" UNIX password:" {
				send_user " (detected additional password prompt - old password)\n"
				send "$oldpwd\n" 
				send_user " (continuing expect loop)\n"
				exp_continue
			}
			-nocase "old password:" {
				send_user " (detected password expired prompt)\n"
				send "$oldpwd\n" 
				send_user " (continuing expect loop)\n"
				exp_continue
			}
			-re "not match the|password mismatch" {
				send_user " (assuming expired password change failed)\n"
				send "passwd\n" 
				expect {
					-nocase "old password:" {
						send_user " (trying with new password)\n"
						send "$newpwd\n" 
						expect {
							-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {
								send_user "\nPassword is current.\n"
								exit 0
							}
							"not match the" {
								send_user "\nPassword change failed.\n"
								exit 1
							}
							default {
								send_user "\nPassword change failed.\n"
								exit 1
							}
						}
					}
					default {
						send_user "\nPassword change failed.\n"
						exit 1
					}
				}
			}
			-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {
				send "$newpwd\n" 
				expect {
					"between changes." {
						send_user "\nPassword change failed.\n"
						exit 1
					}
					-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {
						send "$newpwd\n" 
						expect {
							-re "$prompt" { 
								send_user " (detected shell command prompt)\n"
								send_user "Password successfully changed.\n"
								exit 0
							}
							"Connection to " { 
								send_user " (detected connection closed - assuming password change successful)\n"
								send_user "Password successfully changed.\n"
								exit 0
							}
							default {
								send_user "\nPassword change failed.\n"
								exit 1
							}
						}
					}
				}
			}
			"assword:" {
				send "$newpwd\n" 
				expect {
					" UNIX password:" {
						send_user "\nNew password is expired!\n"
						exit 1
					}
					-nocase "old password:" {
						send_user "\nNew password is expired!\n"
						exit 1
					}
					"assword:" {
						send_user "\nAutomated login failed.\n"
						exit 1
					}
					-re "$prompt" { 
						send_user " (detected shell command prompt)\n"
						send_user "Password is current.\n"
						exit 0
					}
					default {
						send_user "\nAutomated login failed.\n"
						exit 1
					}
				}
			}
			-re "$prompt" { send_user " (detected shell command prompt)\n" }
		}
	}
	-re "$prompt" { send_user " (detected shell command prompt)\n" }
}

send "\n"

expect {
	-re "$prompt" {
		send_user " (changing password at prompt)\n"
		send "passwd\n" 
		expect {
			-re "\[oO\]ld \[pP\]assword:| UNIX \[pP\]assword:" {
				send "$oldpwd\n" 
				expect {
					"You must wait longer" {
						send_user "\nPassword change failed.\n"
						exit 1
					}
					-re "not match the|password mismatch" {
						send "passwd\n" 
						expect {
							-nocase "old password:" {
								send_user " (trying with new password)\n"
								send "$newpwd\n" 
								expect {
									-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {
										send_user "\nPassword is current.\n"
										exit 0
									}
									"not match the" {
										send_user "\nPassword change failed.\n"
										exit 1
									}
									default {
										send_user "\nPassword change failed.\n"
										exit 1
									}
								}
							}
							default {
								send_user "\nPassword change failed.\n"
								exit 1
							}
						}
					}
					-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {
						send "$newpwd\n" 
						expect {
							"between changes." {
								send_user "\nPassword change failed.\n"
								exit 1
							}
							-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {
								send "$newpwd\n" 
								expect {
									-re "$prompt" { 
										send_user " (detected return to shell command prompt)\n"
										send_user "Password successfully changed.\n"
										exit 0
									}
									default {
										send_user "\nPassword change failed.\n"
										exit 1
									}
								}
							}
							"BAD PASSWORD" {
								send_user "\nPassword change failed.\n"
								exit 1
							}
							default {
								send_user "\nPassword change failed.\n"
								exit 1
							}
						}
					}
					default {
						send_user "\nPassword change failed.\n"
						exit 1
					}
				}
			}
		}
	}
	default {
		send_user "\nAutomated login failed.\n"
		exit 1
	}
}

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#!/usr/bin/expect -f

# /usr/local/bin/sshchpwd.exp

# Expect script to change login passwords using SSH, with support for one-time

# tokens (like SecurID), expired passwords (changed before arriving at the

# prompt), on Solaris, AIX, Linux, etc.

# License: GPLv3

# License URI: http://www.gnu.org/licenses/gpl.txt

# Example:

# $ export OLD_PASSWORD="oldpwd"

# $ export NEW_PASSWORD="newpwd"

# $ ./sshchpwd {server} {port} {token}

# The {port} and {token} command-line parameters are optional. If the server

# uses SecurID (or another one-time password), enter it on the command-line as

# the third parameter.

set timeout 15

set server [lindex $argv 0]

set port [lindex $argv 1]

set tokpwd [lindex $argv 2]

set oldpwd $env(OLD_PASSWORD)

set newpwd $env(NEW_PASSWORD)

set prompt "\[>%\\$#\] "

if { $port == "" } { set port "22" }

if { $tokpwd == "" } { set tokpwd $oldpwd }

send_user "connecting to $server on port $port\n"

spawn ssh -p $port $server

# Mission of this first expect - get to the shell command prompt. If the

# password is expired and we have to change it before getting to the prompt,

# then exit 0 (success).

expect {

"(yes/no)? " {

send_user " (detected unknown host key - accepting)\n"

send "yes\n"

send_user " (continuing expect loop)\n"

exp_continue

}

"assword:" {

send_user " (detected password login prompt - possibly token)\n"

send "$tokpwd\n"

expect {

" UNIX password:" {

send_user " (detected additional password prompt - old password)\n"

send "$oldpwd\n"

send_user " (continuing expect loop)\n"

exp_continue

}

-nocase "old password:" {

send_user " (detected password expired prompt)\n"

send "$oldpwd\n"

send_user " (continuing expect loop)\n"

exp_continue

}

-re "not match the|password mismatch" {

send_user " (assuming expired password change failed)\n"

send "passwd\n"

expect {

-nocase "old password:" {

send_user " (trying with new password)\n"

send "$newpwd\n"

expect {

-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {

send_user "\nPassword is current.\n"

exit 0

}

"not match the" {

send_user "\nPassword change failed.\n"

exit 1

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {

send "$newpwd\n"

expect {

"between changes." {

send_user "\nPassword change failed.\n"

exit 1

}

-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {

send "$newpwd\n"

expect {

-re "$prompt" {

send_user " (detected shell command prompt)\n"

send_user "Password successfully changed.\n"

exit 0

}

"Connection to " {

send_user " (detected connection closed - assuming password change successful)\n"

send_user "Password successfully changed.\n"

exit 0

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

"assword:" {

send "$newpwd\n"

expect {

" UNIX password:" {

send_user "\nNew password is expired!\n"

exit 1

}

-nocase "old password:" {

send_user "\nNew password is expired!\n"

exit 1

}

"assword:" {

send_user "\nAutomated login failed.\n"

exit 1

}

-re "$prompt" {

send_user " (detected shell command prompt)\n"

send_user "Password is current.\n"

exit 0

}

default {

send_user "\nAutomated login failed.\n"

exit 1

}

-re "$prompt" { send_user " (detected shell command prompt)\n" }

}

-re "$prompt" { send_user " (detected shell command prompt)\n" }

}

send "\n"

expect {

-re "$prompt" {

send_user " (changing password at prompt)\n"

send "passwd\n"

expect {

-re "\[oO\]ld \[pP\]assword:| UNIX \[pP\]assword:" {

send "$oldpwd\n"

expect {

"You must wait longer" {

send_user "\nPassword change failed.\n"

exit 1

}

-re "not match the|password mismatch" {

send "passwd\n"

expect {

-nocase "old password:" {

send_user " (trying with new password)\n"

send "$newpwd\n"

expect {

-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {

send_user "\nPassword is current.\n"

exit 0

}

"not match the" {

send_user "\nPassword change failed.\n"

exit 1

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {

send "$newpwd\n"

expect {

"between changes." {

send_user "\nPassword change failed.\n"

exit 1

}

-re "\[nN\]ew \[pP\]assword:|\[nN\]ew \[pP\]assword \[aA\]gain:" {

send "$newpwd\n"

expect {

-re "$prompt" {

send_user " (detected return to shell command prompt)\n"

send_user "Password successfully changed.\n"

exit 0

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

"BAD PASSWORD" {

send_user "\nPassword change failed.\n"

exit 1

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

default {

send_user "\nPassword change failed.\n"

exit 1

}

default {

send_user "\nAutomated login failed.\n"

exit 1

}

Download the sshchpwd.exp script.

4 thoughts on “Change Passwords with SSH and Expect”

Greg Barnes says:

April 9, 2014 at 6:18 pm UTC

WARNING: Your password has expired.
You must change your password now and login again!
Changing password for user ed856685.
Changing password for ed856685
(current) UNIX password: (detected additional password prompt – old password)
(continuing expect loop)

New UNIX password: (detected additional password prompt – old password)
(continuing expect loop)

Password unchanged
New UNIX password: (detected additional password prompt – old password)
(continuing expect loop)

Password unchanged
New UNIX password: (detected additional password prompt – old password)
(continuing expect loop)

Password unchanged
passwd: Authentication token manipulation error
Connection to emghlc002 closed.
send: spawn id exp6 not open
while executing
“send “\n””
(file “./changepwssh.sh” line 145)

its like its not seeing that is asking for new password. Can you please help?

Thanks
Greg Barnes says:

April 9, 2014 at 4:58 pm UTC

Forgive me for not being real smart on this but where do I put the current pw and the new pw in the script?

Thanks
Greg
Stefano says:

October 17, 2012 at 3:44 am UTC

The mess is changing passwords every three months. Who thought about this awful thing is surely work on windows, a different world.
I faced a similar situation in the place I’ve been working in for 15 years. Then I resigned (that was not the only reason, though). It’s better to become a farmer than continue with this paranoia.
Greetings
- JS Morisset says:
  
  April 9, 2014 at 5:01 pm UTC
  
  Environment variables, as shown in the example:
  
  # Example: # # $ export OLD_PASSWORD="oldpwd" # $ export NEW_PASSWORD="newpwd" # $ ./sshchpwd {server} {port} {token}
  
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  # Example:
  #
  #    $ export OLD_PASSWORD="oldpwd"
  #    $ export NEW_PASSWORD="newpwd"
  #    $ ./sshchpwd {server} {port} {token}
  
  js.

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