I needed a script to copy a file out to a dmz (using scp), so I wrote this snippet w/ expect. It took a bit of monkeying with it to get it right (especially the part when it gets a "prompt" back from the system), but it works well. (it is functional, just not pretty). "I am more of a butcher than a hacker" Joe 
sub copyover {
    $scp=Expect->spawn("/usr/bin/scp ${srcpath}/$file $who:${destpath}
+/$file");
    $scp->expect(30,"ssword: ") || die "Never got password prompt from
+ $dest:$!\n";
    print $scp 'password' . "\n";
    $scp->expect(30,"-re",'$\s') || die "Never got prompt from parent 
+system:$!\n";
    $scp->soft_close();
    return;
}

[download]

Replies are listed 'Best First'.
Re: expect w/scp
by tadman (Prior) on Mar 23, 2001 at 06:14 UTC
    It's an interesting use of Expect, but ssh can be configured to log in without the password prompt, which may be more appealing from a security standpoint because you get key-level authentication instead of a simple password.

    Of course, OpenSSH and SSH act differently with regards to configuration. Look in the man page for references to "authorized_keys" for more info.

    This is a little off-topic, but here is how SSH-SSH (for lack of a better term) operates.

    With SSH2, on server A, you would have a file like: 
          ~/.ssh2/identification
      ----------------------
      IdKey id_dsa_1024_a

    [download]
    On server B, where you want to connect with no password: 
          ~/.ssh2/authorization
      ----------------------
      Key id_dsa_1024_a.pub

    [download]
    You would copy the "id_dsa_1024_a.pub" key from server A over to server B and put it in ~/.ssh2/

    ObPerl:
    Just for kicks, here's a Quick Hack that I put together to schlep keys around from one box to several others. 
    #!/usr/bin/perl
#
# ssh-addauth - Adds automatic login to a remote SSH server
#               from the current machine.

use strict;

use Sys::Hostname;

my ($default_key)  = "id_dsa_1024_a.pub";

# These parameters may come from: /etc/ssh2/ssh2_config
my ($ssh_dir)      = ".ssh2";           # UserConfigDirectory
my ($ssh_authfile) = "authorization";   # AuthorizationFile
my ($hostname)     = hostname();
my ($username)     = getpwuid($<);

foreach my $arg (@ARGV)
{
        AddAuth($arg);
}

sub AddAuth
{
        my ($remote_host) = @_;

        system ("scp $ENV{HOME}/$ssh_dir/$default_key $remote_host:$ss
+h_dir/${username}_${hostname}_dsa_1024.pub");
        system ("ssh $remote_host \"echo 'Key ${username}_${hostname}_
+dsa_1024.pub' >> $ssh_dir/$ssh_authfile\"");
}

    [download]
[reply]
[d/l]
[select]
Re (tilly) 1: expect w/scp
by tilly (Archbishop) on Mar 23, 2001 at 07:49 UTC
    I would like to second tadman's recommendation of configuring ssh so you can lose the passwords in scripts. In addition I would recommend using rsync over scp. With ssh you can handle a lot of potential failure conditions by just saying, "I will syncronize ever X minutes anyways, so it doesn't mastter too much if I bomb out whenever there is a problem..."

    That facility can be very useful.

[reply]

Back to Cool Uses for Perl