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 connection to $server\n";

##</code><code>##

    $>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,keyboard-interactive.
    Next method to try is password.
    Trying password authentication.
    Will not query passphrase in batch mode.
    Authentication methods that can continue: password,publickey,keyboard-interactive.
    Next method to try is password.
    Trying password authentication.
    Will not query passphrase in batch mode.
    Authentication methods that can continue: password,publickey,keyboard-interactive.
    Next method to try is password.
    Trying password authentication.
    Will not query passphrase in batch mode.
    Authentication methods that can continue: password,publickey,keyboard-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,keyboard-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,keyboard-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,keyboard-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/SFTP.pm line 63.

##</code><code>##

> sftp -oPort=10022 -oIdentityFile=path/sftp_download user@downloads-server
<br>Connecting to downloads-server...
<br>sftp>