Sigh. It's Friday afternoon and the code doesn't work. I am trying to automate the remote configuration of a slew of Netscreen routers. They allow an SSH connection, and I've been playing with btrott's Net::SSH::Perl module. Right now I'm a bit stuck.

If I open a shell, I can type in a command and get the output back, but if I try to send it a command, it just hangs there. I must be doing something wrong but I can't see what. Stripped to the essentials, the code looks like this:

#! /usr/bin/perl -w

use strict;
use Net::SSH::Perl;
use Term::ReadKey;

my $host = '10.0.0.254';
my $user = 'foo';
my $pw   = 'bar';

my $ssh = Net::SSH::Perl->new( $host, (
  protocol => '1',
  debug => 1,
)) or die "Could not create Net::SSH::Perl object: $!\n";

$ssh->login($user, $pw);

if( @ARGV ) {
  ReadMode('raw');
  $ssh->shell;
  ReadMode('restore');
}
else {
  my($stdout, $stderr, $exit) = $ssh->cmd("get config\n");
  print <<"SSH_END";
STDOUT BEGIN
$stdout
STDOUT END

STDERR BEGIN
$stderr
STDERR END

EXIT=$exit
SSH_END
}

[download]

So if I run this code with some stuff on the command line, it'll do the shell-based approach. This produces the following result:

localhost: Reading configuration data /home/foo/.ssh/config
localhost: Reading configuration data /etc/ssh_config
localhost: Connecting to 10.0.0.254, port 22.
localhost: Remote protocol version 1.5, remote software version SSH Pr
+otocol Compatible Server SCS 2.0
localhost: Net::SSH::Perl Version 1.23, protocol version 1.5.
localhost: No compat match: SSH Protocol Compatible Server SCS 2.0.
localhost: Connection established.
localhost: Waiting for server public key.
localhost: Received server public key (768 bits) and host key (1024 bi
+ts).
localhost: Host '10.0.0.254' is known and matches the host key.
localhost: Encryption type: DES3
localhost: Sent encrypted session key.
localhost: Received encryption confirmation.
localhost: RSA authentication using agent refused.
localhost: RSA authentication failed: Can't load public key.
localhost: Trying password authentication.
localhost: Requesting pty.
localhost: Requesting shell.
localhost: Entering interactive session.
Remote Management Console

foo-> get config
Total Config size 6527:
set auth type 0
set auth timeout 20
...
foo-> exit

[download]

Thus I can see that I can contact the router and get what I want out of it. On the other hand, if I run the script with a blank command line, it runs the other part of the conditional, and produces the following output:

ocalhost: Reading configuration data /home/dlandgre/.ssh/config
localhost: Reading configuration data /etc/ssh_config
localhost: Connecting to 10.0.0.254, port 22.
localhost: Remote protocol version 1.5, remote software version SSH Pr
+otocol Compatible Server SCS 2.0
localhost: Net::SSH::Perl Version 1.23, protocol version 1.5.
localhost: No compat match: SSH Protocol Compatible Server SCS 2.0.
localhost: Connection established.
localhost: Waiting for server public key.
localhost: Received server public key (768 bits) and host key (1024 bi
+ts).
localhost: Host '10.0.0.254' is known and matches the host key.
localhost: Encryption type: DES3
localhost: Sent encrypted session key.
localhost: Received encryption confirmation.
localhost: RSA authentication using agent refused.
localhost: RSA authentication failed: Can't load public key.
localhost: Trying password authentication.
localhost: Sending command: get config

localhost: Entering interactive session.
localhost: Warning: ignoring packet of type 15

[download]

... and then it just hangs there at that point.

I must admit to cut'n'paste programming. I just pinched this stuff out of the documentation, so I don't have much idea of what I'm doing :) I'm puzzled by the "packet of type 15", by the fact that I appear to send a command before entering an interactive session, but I'm leaning towards suffering from buffering to sweep that one under the carpet.

I registered a packet handler for those odd packets with:

  $ssh->register_handler( 15, sub {
    my($s, $pkt) = @_;
    print "\ngot: ", $pkt->get_str, "\n";
  });

[download]

...but that just produces:

Use of uninitialized value in addition (+) at /usr/local/share/perl/5.
+6.1/Net/SSH/Perl/Buffer.pm line 125.
substr outside of string at /usr/local/share/perl/5.6.1/Net/SSH/Perl/B
+uffer.pm line 48.

Use of uninitialized value in print at ./getcfg line 27.
got:

[download]

And at this point I'm starting to run out of ideas. Any clues I can use will be warmly welcomed.


print@_{sort keys %_},$/if%_=split//,'= & *a?b:e\f/h^h!j+n,o@o;r$s-t%t#u'

In reply to differences between Net::Perl::SSH shell and cmd methods by grinder

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