0

I have written a code snippet in TCL expect to connect from Server 1 to Server 2 using ssh. Users already may have set passwordless communication between Server 1 and Server 2, or it may ask for a password. Code should handle all these three below possible scenarios:

  1. If passwordless login is enabled between Server 1 and Server 2
  2. No Passwordless login is enabled, Password: prompt is displayed
  3. If user enters incorrect Password, a second Password: prompt is expected where ctrl+c will be entered and will exit.

Please find below the code

#!/usr/bin/expect -f
lassign $argv 1 2 
spawn ssh -o StrictHostKeyChecking=no $1@$2

expect {
      "*]#" { send -- "sleep 0\n" }  #Prompt when passwordless is active and user have logged in
      "Password: " {send -- "$2\n"   #Password prompt when no passwordless is active.
             exp_continue }
      "Password: " {send -- "^C" }   # Second Password Prompt when the wrong password is entered 
                                       in previous step. From here code should exit with a message
       }
 expect "*]#"                # After SSH is successful

I am not able to handle the second Password: prompt for an incorrect password where the code should exit with an appropriate message to the user. I am running the script ./testssh.exp username password.

0

Perhaps:

set count 0
expect {
    "Password:" {
        if {[incr count] == 2} {
            # this is the 2nd time, send Ctrl+C
            send -- \x3
            expect eof
            error "incorrect password"
        } else {
            send -- "$2\r"
            exp_continue
        }
    }
    "$prompt"
}
# successfully logged in.
send -- something 
...
1
  • Unfortunately it navigated to # successfully logged in. send -- something block even after wrong password
    – newuser
    Apr 29 '20 at 9:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.