Once again, thanks so far. I have tried the sugested method and I have got a little further. As well as changing my code I have switched on the debug mode. Bellow is the code that I am using

#perl

use Net::SSH::Perl;

$identity = ".ssh/id_dsa";
$debug_level = 1;
$protocol = 1;
$host = "192.211.12.45";
$usr = "dm";

$args{identity_files} = [ $identity ];
$args{debug} = [ $debug_level ];
$args{protocol} = $protocol;

$ssh = Net::SSH::Perl->new( $host,
%args);

$ssh->login("$usr");
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And here is the output that I get from the code when I run it.

target: Reading configuration data /home/dm/.ssh/config
target: Reading configuration data /etc/ssh_config
target: Connecting to 192.211.12.45, port 22.
target: Remote protocol version 1.99, remote software version OpenSSH_
+3.1p1
target: Net::SSH::Perl Version 1.23, protocol version 1.5.
target: No compat match: OpenSSH_3.1p1.
target: Connection established.
target: Waiting for server public key.
target: Received server public key (768 bits) and host key (1024 bits)
+.
target: Host '192.211.12.45' is known and matches the host key.
target: Encryption type: DES3
target: Sent encrypted session key.
target: Received encryption confirmation.
target: RSA authentication failed: Can't load public key.
target: Doing challenge response authentication.
target: No challenge presented.
target: Trying password authentication.
target: Will not query passphrase in batch mode.
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It looks to me like I have a problem with the file that I am presenting? Which file should I be presenting, as you can see from the code I am using the id_dsa file.
I hope this error is meaningful to someone :-)

Thanks again so far.