Re: [Expectperl-discuss] Problem catching the SSH2 prompt using Expect

[<RGi...@a1...>]

> I am using Expect 1.15 on the Perl for Cygwin release 5.6.1-2. I 
> want to use Expect with SSH2 to automate some commands that I have to 
do 
> regularly on remote servers.

First of all, please note the following FAQs from Expect:

  I want to automate password entry for su/ssh/scp/rsh/...

  You shouldn't use Expect for this.  Putting passwords,
  especially root passwords, into scripts in clear text can
  mean severe security problems.  I strongly recommend using
  other means.  For 'su', consider switching to 'sudo', which
  gives you root access on a per-command and per-user basis
  without the need to enter passwords.  'ssh'/'scp' can be set
  up with RSA authentication without passwords.  'rsh' can use
  the .rhost mechanism, but I'd strongly suggest to switch to
  'ssh'; to mention 'rsh' and 'security' in the same sentence
  makes an oxymoron.
  It will work for 'telnet', though, and there are valid uses
  for it, but you still might want to consider using 'ssh', as
  keeping cleartext passwords around is very insecure.


  I want to use Expect to automate [anything with a buzzword]...

  Are you sure there is no other, easier way?  As a rule of
  thumb, Expect is useful for automating things that expect to
  talk to a human, where no formal standard applies.  For
  other tasks that do follow a well-defined protocol, there
  are often better-suited modules that already can handle
  those protocols.  Don't try to do HTTP requests by spawning
  telnet to port 80, use LWP instead.  To automate FTP, take a
  look at the Net::FTP manpage or "ncftp"
  (http://www.ncftp.org).  You don't use a screwdriver to
  hammer in your nails either, or do you?


> But so far I have not been able to do this properly. I am using F-
> Secure SSH for Windows, maybe this causes some trouble?

Definitely, you shouldn't mix native Windows applications with Cygwin.  
Use the 'ssh' from Cygwin instead.

> With F-Secure SSH2, I am not 
> able to give any parameter to the process, and with a sftp2 from 
> SSH, the password is entered succesfully by the script after catching 
the 
> password prompt, but then I can't do anything else, as Expect doesn't 
seem 
> to catch the prompt given by sftp2.
> 
> Some other tests seem to show that I have the same problem when 
> using ftp. 

Again, always use Cygwin applications.  Expect cannot deal with native 
Windows applications, the underlying model is too different.  That's 
why there is not native Windows version of IO-Tty, which Expect builds 
upon.

I'd recommend you look into RSA authentication without passphrase to 
automate your remote commands without the need to enter a password.  
Then you probably don't need Expect, a simple

 $output = qx(ssh $remote_host $command);

or similar system() call should suffice.  Expect is very useful if you 
have to emulate a human at the keyboard, for other tasks it's just 
overkill.

Hope this helps,

Roland
--
RGi...@cp...