Thank you for the pointer, unfortunatelly it does not work.

I've seen that on other modules like Net::SSH2, auth_publickey expects the path for both public and private keys.

It appears not to be the case with Net::SSH::Perl. Adding the public key does not change the outcome:

my %params = (
            "protocol"         => '2',
            "use_pty"          => 0,
            "options"          => ["stricthostkeychecking no"],
            "identity_files"   => ["client_key","client_key.pub"],
            "debug"            => 1,
        );

$ssh = Net::SSH::Perl->new($server, %params);# debug=>1, identity_file
+s=>\@KEYFILE);
$ssh->login();
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localhost: Authentication methods that can continue: publickey,passwor
+d,keyboard-interactive.
localhost: Next method to try is publickey.
localhost: Trying pubkey authentication with key file 'client_key'
Wrong key type at C:/Strawberry/perl/site/lib/Net/SSH/Perl/Auth/Public
+Key.pm line 83.
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If I try having the public key in the first place it just fails and tries the next one:

localhost: Next method to try is publickey.
localhost: Trying pubkey authentication with key file 'client_key.pub'
Use of uninitialized value $object in substitution (s///) at C:/Strawb
+erry/perl/site/lib/Net/SSH/Perl/Key.pm line 109.
Use of uninitialized value $object in substitution (s///) at C:/Strawb
+erry/perl/site/lib/Net/SSH/Perl/Key.pm line 109.
localhost: Will not query passphrase for 'client_key.pub' in batch mod
+e.
Use of uninitialized value $object in substitution (s///) at C:/Strawb
+erry/perl/site/lib/Net/SSH/Perl/Key.pm line 109.
Use of uninitialized value $object in substitution (s///) at C:/Strawb
+erry/perl/site/lib/Net/SSH/Perl/Key.pm line 109.
localhost: Loading private key failed.
localhost: Trying pubkey authentication with key file 'client_key'
Wrong key type at C:/Strawberry/perl/site/lib/Net/SSH/Perl/Auth/Public
+Key.pm line 83.
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I'm going to try all the key formats I manage to generate to check if there any issue there, since I don't know what else might be causing the problem.

Regards.

Found out a format that worked!

ssh-keygen by default generates keys like:

-----BEGIN OPENSSH PRIVATE KEY-----
...
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I tried other combinations until I found one that worked:

$ openssl genrsa -out privatekey

-----BEGIN RSA PRIVATE KEY-----
...

$ chmod 600 privatekey
$ ssh-keygen -y -f privatekey > publickey
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Running the script again, results in a successful login:

localhost: Trying pubkey authentication with key file 'privatekey'
localhost: Login completed, opening dummy shell channel.
localhost: channel 0: new [client-session]
localhost: Requesting channel_open for channel 0.
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