SCP connection

mantra2006 has asked for the wisdom of the Perl Monks concerning the following question:

hello

I was using the following script to connect to remote host and copy a file. The script actually copies the file. But when I run the script it asks me password for remote host. Is there a way to automate so that the script won't ask for password and everything copy when the script is run

use::warnings;
use::strict;

my $rmthost  = 'backupserver';
my $rmtuser  = 'anonymous';
my $rmtpath  = 'tempdir';
my $lclpath  = '/home/user/testdir';
my $lclglob  = '*.txt';
my $flagfile = '.last_backup';
my $r_opts   = "'ssh -l $rmthost $rmtuser'";
my $lclfiles = "$lclpath/$lclglob";

sub modtime {
  my $file  = shift;
  my @stats = stat $file or return 0;
  return $stats[9];
}

while (1) {
  my $timestamp = modtime("$lclpath/$flagfile");
  my $run = grep {modtime($_) > $timestamp} glob $lclfiles;
  if ($run) {
    system "scp  $r_opts $lclfiles $rmthost:$rmtpath";
    open  FLAG, ">$lclpath/$flagfile" or die;
    close FLAG or die;
  }
  sleep 60;
}
[download]

20060724 Janitored by Corion: Added formatting, code tags, as per Writeup Formatting Tips

Considered by Hue-Bond: Mark as OT, since this isn't strictly a Perl question
Unconsidered by Arunbear: Keep: 24, Edit: 19, Reap: 2

Comment on SCP connection Download Code

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Re: SCP connection by Joost (Canon) on Jul 24, 2006 at 18:42 UTC
If you set up public/private key authentication without a passphrase, you can scp and ssh without entering passwords. (usually, the ssh server can also be configured to restrict access to specific actions / programs for certain keys) Check out the ssh-keygen program and your ssh server documentation. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re: SCP connection by ikegami (Patriarch) on Jul 24, 2006 at 18:51 UTC
What is `use::warnings; use::strict;` [download] They don't do anything. `use::warnings; # Returns the var "warnings" in the pkg "use". use::strict; # Returns the var "strict" in the pkg "use". print $abc; # "use strict" would give an error (not declared), # "use warnings" would give a warning (undefined), # but we get nothing.` [download] You want `use warnings; use strict;` [download]	[reply] [d/l] [select]
Re: SCP connection by madbombX (Hermit) on Jul 24, 2006 at 18:53 UTC
I would suggest that you check out the module from CPAN called Net::SCP. It should be able to do what you are looking to do. With regard to getting the password into the script. This isn't secure practice. A slightly more secure practice would be to generate a pwless ssh key and use that key to connect to the server. `use Net::SCP qw(scp); my ($host, $username) = ("example.com", "eric"); $scp = Net::SCP->new( { "host"=>$hostname, "user"=>$username } ); for my $file (@files) { $scp->put($file) or warn $scp->{errstr}; }` [download] However, if you are really intent on hard-coding the password into the server, then consider using Net::SSH2. It allows all the different types of authentication. `use Net::SSH2; my $ssh2 = Net::SSH2->new(); $ssh2->connect('example.com') or die ("SSH2 Connect Error: $!"); if ($ssh2->auth_keyboard('password')) { for my $file (@files) { scp_put($file); } }` [download] Note: All the code is untested.	[reply] [d/l] [select]
Re^2: SCP connection by rodion (Chaplain) on Jul 24, 2006 at 20:36 UTC
Net::SSH::Perl has a perl-only implementation of SSH-1 and SSH-2, with a variety of authentications schemes. The docs identify some performance advantages to being all perl, but more relevant here they say It also simplifies the process of using password-based authentications; when writing a wrapper around ssh you probably need to use Expect to control the ssh client and give it your password. Net::SSH::Perl has built-in support for the authentication protocols, so there's no longer any hassle of communicating with any external processes.	[reply]
Re^2: SCP connection by mantra2006 (Hermit) on Jul 24, 2006 at 20:00 UTC
hey thanks for the reply..where can I get Net::SCP qw(scp); or Net::SSH2; and where do I copy these files in my directory?	[reply]
Re^3: SCP connection by Joost (Canon) on Jul 24, 2006 at 20:48 UTC
Easiest is probably to use the CPAN shell: `perl -MCPAN -e 'shell' install Net::SCP` [download] (It'll ask some configuration questions the first time you run it) "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l]
Re^4: SCP connection by mantra2006 (Hermit) on Jul 25, 2006 at 18:29 UTC
Re^5: SCP connection by Joost (Canon) on Jul 25, 2006 at 20:49 UTC
Re: SCP connection by superfrink (Curate) on Jul 24, 2006 at 19:17 UTC
You can also look into ssh-agent. This lets you type your password once (to decrypte ssh keys) and then your later processes can use the decrypted key. The tutorial I used to set it up is at http://mah.everybody.org/docs/ssh. Be sure to read the security notes http://www.unixwiz.net/techtips/ssh-agent-forwarding.html#sec In particular any process that runs as the same user or as root will be able to use the decrypted credentials to connect to the destination machine.	[reply]