Re: using expect to log into devices

[Lee <ler762 () gmail com>]

On 7/20/18, Scott Weeks <surfer () mauigateway com> wrote:
> I have looked extensively on the web for an answer
> and cannot find one, so I come to you guys.  I am
> not allowed to use modules in PERL or Python or I
> wouldn't have to do it this way.  I have to do this
> all in Expect and I am a newbie at it.
>
> Also, maybe I'm having the Friday afternoon "I want
> to go home" mental block and the answer is right in
> front of my nose.
>
> I have a file with 1000s of devices and another file
> with a list of commands.  The program issues all
> commands for a device and then moves on to the next
> one using nested loops.  In the debug I see the
> "spawn_id expNN" (where NN is a number that, I
> believe is representative of the number of file
> descriptors used in the system) increment only when
> a device does not respond.  As long as a device
> responds before the timeout period I see the expNN
> number does not increase.  As soon as a device
> doesn't respond the expNN count goes up and I can't
> figure out why.  Once I hit a certain expNN the
> program exits ungracefully; usually somewhere between
> 2500 and 3500 devices because our FD is set to 256
> and that's how long it takes for 256 devices to not
> respond before the timeout period.  Can anyone tell
> me why?  Here is the relevant config snippet.  I've
> tried every iteration of close and wait I found and
> no love...

'close $spawn_id' is wrong, so maybe that's it?

man expect
  close [-slave] [-onexec 0|1] [-i spawn_id]
        closes  the  connection to the current process.  ...  The -i
flag declares the
        process to close corresponding to the named spawn_id.
      <.. snip ..>
        No  matter  whether  the connection is closed implicitly or
explicitly, you
        should call wait to clear up the corresponding kernel process
slot.  close
        does not call wait since there is no guarantee that closing a process
        connection will cause it to exit.  See wait below for more info.

get rancid from here
  ftp://ftp.shrubbery.net/pub/rancid/

and take a look at clogin
  (which allows you to do 'clogin -x fileName dev1 dev2 ... devN' to
run the commands
   in 'fileName' on the list of devices)

The eof and timeout cases are basically
  { catch {close}; catch {wait}; }

Regards,
Lee


> You'll want to put this into a fixed width font like
> Courier New or it'll just be a mess.
>
>
> foreach element $device {
>
> send_user "\n\n"
>
> send_user "#####################################\n"
> send_user "######  BEGIN $element  #######\n"
> send_user "#####################################\n"
>
>    spawn ssh -q -o StrictHostKeyChecking=no $username@$element
>
> expect {
>   timeout { send_user "\nfailed to get password prompt\n\n"
>             send_user "#####################################\n"
>             send_user "#######  END $element  ########\n"
>             send_user "#####################################\n"
>             send_user "\n\n\n"; continue
>             close $spawn_id
>             wait
>           }
>   eof { send_user "\nssh failure for $element\n\n"
>         send_user "#####################################\n"
>         send_user "#######  END $element  ########\n"
>         send_user "#####################################\n"
>         send_user "\n\n\n"; continue
>         close $spawn_id
>         wait
>       }
>   "assword" {
>   send "$password\n"
>             }
>        }
>
>
> expect {
>   timeout { send_user "\npassword did not work or enable mode not
>                         achieved\n\n"
>             send_user "#####################################\n"
>             send_user "#######  END $element  ########\n"
>             send_user "#####################################\n"
>             send_user "\n\n\n"; continue
>             close $spawn_id
>             wait
>           }
>   eof { send_user "\npassword failure for $element\n\n"
>         send_user "#####################################\n"
>         send_user "########  END $element  #########\n"
>         send_user "#####################################\n"
>         send_user "\n\n\n"; continue
>         close $spawn_id
>         wait
>       }
>         "" {
>               send "term len 0\n"
> #             send "skip-page-display\n"
>
>               foreach command $commands {
>                 expect "#"
>                 send "$command\n"
>                 send_user "\n\n"
>                                         }
>             }
>        }
>
> send "exit\n"
> send "exit\n"
>
> send_user "#####################################\n"
> send_user "#######  END $element  ########\n"
> send_user "#####################################\n"
> send_user "\n\n\n"
>
> close
> wait
> }
>
>
> Thanks!
> scott
>
> ps; I realize my indenting of the curly braces and other
> things are not standard...  :)