Question

I have a simple perl test script which uses Net::SSH2, and I’m having trouble getting it to work with public key authentication.

Note: After reading a couple of replies, I realise that I should mention that I created the script to help narrow down a problem I was having with another application that uses Net::SSH2. It’s therefore not possible for me to switch to an alternative package such as Net::OpenSSH or Net::OpenSSH::Compat::SSH2.

Note Update: As salva pointed out, Net::OpenSSH::Compat::SSH2 can be used without having to patch the original application.

Here’s the code:

use strict;
use warnings;
use 5.10.0;

use Net::SSH2;

my $ssh2 = Net::SSH2->new();
my $auth;

if ( $ssh2->connect('hostname') ) {

    $auth = $ssh2->auth_publickey(
       'username',
       '/home/mike/.ssh/id_rsa.pub',
       '/home/mike/.ssh/id_rsa',
       'password'
    );  
}   

if ($auth && $ssh2->auth_ok) {
    say 'Success';
} else {
    say join ', ', $ssh2->error;
}  

I have been generating key pairs using ssh-keygen on Ubuntu:

ssh-keygen -t rsa
ssh-copy-id user@server
ssh user@server

The above works correctly – I can SSH to the server.

When I run the Perl code, I get the following error when using a password protected key:

-16, LIBSSH2_ERROR_FILE, Unable to initialize private key from file

If I try with a non-password protected key, it works correctly.

I have the following libraries installed:

Net::SSH2         0.35

libssh2-1         1.2.2-1
libssh2-1-dev     1.2.2-1
ssh               1:5.3p1-3ubuntu6
openssh-server    1:5.3p1-3ubuntu6
openssh-client    1:5.3p1-3ubuntu6
openssl           0.9.8k-7ubuntu8.6
libssl-dev        0.9.8k-7ubuntu8.6

The plot thickens

If I remove libssh2-1 and libssh2-1-dev, I get an error, as expected:

Can't load '/usr/local/lib/perl/5.10.1/auto/Net/SSH2/SSH2.so'

If I then build libssh2 from source, I am unable to reinstall Net::SSH2, as it can’t find the development headers. However, if I reinstall libssh2-1 and libssh2-1-dev and then build and install libssh2 from source, it works.

Does that mean that the build of libssh2-1-dev on Ubuntu 10.04 is at fault? If so, how do I install libssh2 from source and correctly install Net::SSH2, without requiring libssh2-1-dev. I presume that the build from source is overwriting or overriding the Ubuntu package.

UPDATE

As noted in Daniel Stenberg’s reply, the Ubuntu 10.04 package is now a little out of date (version 1.2.2, compared with the latest stable build at 1.2.8). Installing libssh2 from source ‘over the top’ of the Ubuntu package solves the problem. However, this feels messy to me. How can I remove the Ubuntu package, install libssh2 from source, and still build Net::SSH2 — how do I tell Net::SSH2 where to find the libssh2 development headers?

UPDATE 2

salva came to the rescue again, and showed how the Net::SSH2 installer can be configured with lib and include directories, so that it may be used with the source install of libssh2. Thanks salva! Note that instead of patching Makefile.PL, it’s possible to just override the $lib and $inc variables at the top of Makefile.PL. I wasn’t aware of this until I looked at salva’s patch.

Answer 1

I have been able to successfully log into a server using a pass-phrase protected key with Net::SSH2 from the the Ubuntu 11.04 libnet-ssh2-perl package.

Anyway, consider using Net::OpenSSH or Net::OpenSSH::Compat::SSH2 instead of Net::SSH2.

Update: Net::OpenSSH::Compat::SSH2 tries to be a replacement for Net::SSH2. There is no need to patch the application in order to try it:

perl -MNet::OpenSSH::Compat=Net::SSH2 yor_app.pl