SFTP connection failure with Perl “Net::SFTP” module

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

I am trying to connect to SFTP server using Perl but I get the following connection error:

Permission denied at /app/perl-5.24.3/lib/site_perl/5.24.3/Net/SFTP.pm line 63.

My connection code 'sftp_test2.pl':

    use strict;
    use warnings;
    
    use Net::SFTP;
    
    my $server   = 'downloads-server';
    my $user     = 'user';
    my $port     = "10022";
    my $password = '';
    
    my %args = (
         user => "$user",
         password => '',
         port => "$port",
         ssh_args => {
             user => "$user",
             password => '',
             identity_files => [ 'path/sftp_download'],
             port => "$port",
             protocol=>'2,1',
             debug => 1,
         }
    );
    
    my $sftp=Net::SFTP->new($server, %args) or die "could not open con
+nection to $server\n";
[download]

execution:

    $>perl sftp_test2.pl
    Reading configuration data path/home/.ssh/config
    Reading configuration data /etc/ssh_config
    Connecting to downloads-server, port 10022.
    Remote version string: SSH-2.0-CrushFTPSSHD
    Remote protocol version 2.0, remote software version CrushFTPSSHD
    Net::SSH::Perl Version 2.14, protocol version 2.0.
    No compat match: CrushFTPSSHD.
    Connection established.
    Sent key-exchange init (KEXINIT), waiting for response.
    Using diffie-hellman-group-exchange-sha256 for key exchange
    Host key algorithm: ssh-rsa
    Algorithms, c->s: aes256-ctr hmac-sha2-512-etm@openssh.com none
    Algorithms, s->c: aes256-ctr hmac-sha2-512-etm@openssh.com none
    Entering Diffie-Hellman Group Exchange.
    SSH2_MSG_KEX_DH_GEX_REQUEST(2048<4096<8192) sent
    Sent DH Group Exchange request, waiting for reply.
    Received 4096 bit DH Group Exchange reply.
    Generating new Diffie-Hellman keys.
    Entering Diffie-Hellman key exchange.
    Sent DH public key, waiting for reply.
    Received host key, type 'ssh-rsa'.
    Host 'downloads-server' is known and matches the host key.
    Verifying server signature.
    Send NEWKEYS.
    Waiting for NEWKEYS message.
    Enabling encryption/MAC/compression.
    Sending request for user-authentication service.
    Service accepted: ssh-userauth.
    Trying empty user-authentication request.
    Authentication methods that can continue: password,publickey,keybo
+ard-interactive.
    Next method to try is password.
    Trying password authentication.
    Will not query passphrase in batch mode.
    Authentication methods that can continue: password,publickey,keybo
+ard-interactive.
    Next method to try is password.
    Trying password authentication.
    Will not query passphrase in batch mode.
    Authentication methods that can continue: password,publickey,keybo
+ard-interactive.
    Next method to try is password.
    Trying password authentication.
    Will not query passphrase in batch mode.
    Authentication methods that can continue: password,publickey,keybo
+ard-interactive.
    Next method to try is password.
    Next method to try is publickey.
    Publickey: testing agent key 'my-server'
    Authentication methods that can continue: password,publickey,keybo
+ard-interactive.
    Next method to try is password.
    Next method to try is publickey.
    Publickey: testing agent key 'path/home/.ssh/id_rsa'
    Authentication methods that can continue: password,publickey,keybo
+ard-interactive.
    Next method to try is password.
    Next method to try is publickey.
    Trying pubkey authentication with key file 'path/sftp_download'
    Authentication methods that can continue: password,publickey,keybo
+ard-interactive.
    Next method to try is password.
    Next method to try is publickey.
    Permission denied at /app/perl-5.24.3/lib/site_perl/5.24.3/Net/SFT
+P.pm line 63.
[download]

I thought that it is related to my private key, but I can connect via unix command:

> sftp -oPort=10022 -oIdentityFile=path/sftp_download user@downloads-s
+erver
<br>Connecting to downloads-server...
<br>sftp>
[download]

I tried to find a solution in many articles and also tried few code variations, but without a success. I suspected that it may be related to multiple connection failing attempts with password so I removed the password authentication from "%AUTH_MAP" in the file "app/perl-5.24.3/lib/site_perl/5.24.3/x86_64-linux/Net/SSH/Perl/AuthMgr.pm" and it connected as expected!

As I cannot edit Perl modules, I have to find other solution. Is there a way to force using only/first key authentication instead of password?

Thanks in advance! Mike

Comment on SFTP connection failure with Perl “Net::SFTP” module Select or Download Code

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Re: SFTP connection failure with Perl “Net::SFTP” module by poj (Abbot) on May 06, 2019 at 09:27 UTC
Try `ssh_args => { user => $user, options => [ 'PasswordAuthentication no' ], identity_files => [ 'path/sftp_download'], port => $port, protocol =>'2,1', debug => 1, }` [download] poj	[reply] [d/l]
Re^2: SFTP connection failure with Perl “Net::SFTP” module by Michaels (Novice) on May 06, 2019 at 10:47 UTC
Thank you very much !!! It solved the problem! I already tried to use 'PasswordAuthentication no' but differently. Thanks! Mike	[reply]
Re: SFTP connection failure with Perl “Net::SFTP” module by thanos1983 (Parson) on May 06, 2019 at 08:16 UTC
Hello Michaels, I would suggest to comment out the `identity_files` and also `password`. Simply do this: `#!/usr/bin/perl use strict; use warnings; use Net::SFTP; my $host = '127.0.0.1'; my %args = ( user => 'user', ssh_args => [ port => "10022" ] ); my $sftp = Net::SFTP->new($host, %args); my $ls = $sftp->ls('/sample/path'); print "$_->{filename}\n" for (@$ls);` [download] I would also suggest to use the module Net::SFTP::Foreign. You can find more information as to why on a previoudly asked question Re: Using Net::SFTP. Hope this helps, BR. Seeking for Perl wisdom...on the process of learning...not there...yet!	[reply] [d/l] [select]
Re^2: SFTP connection failure with Perl “Net::SFTP” module by Michaels (Novice) on May 06, 2019 at 08:34 UTC
Thank you thanos1983! But how can I point to the private key file if I'll remove 'identity_files'? BR, Michael	[reply]
Re^3: SFTP connection failure with Perl “Net::SFTP” module by thanos1983 (Parson) on May 06, 2019 at 09:15 UTC
Hello Michaels, If you do not use default path of you SSH keys then you can use the option `identity_files` but you need to remove the `password`. Let me know if it works for you. BR / Thanos Seeking for Perl wisdom...on the process of learning...not there...yet!	[reply] [d/l] [select]
Re^4: SFTP connection failure with Perl “Net::SFTP” module by Michaels (Novice) on May 06, 2019 at 09:25 UTC
Re^5: SFTP connection failure with Perl “Net::SFTP” module by thanos1983 (Parson) on May 06, 2019 at 09:42 UTC