Hi!

Is FTP is the protocol, use Net::FTP. You can resume a file transfer from where is was interrupted by using the following syntax:

$result = $ftp->get($remotefile, $localfile, $offset);
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In $offset you can specify the position from where the transfer should start. For HTTP, you can use LWP this way:

$request->header('Range' => "bytes=$local_size-$remote_size");
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This should be added as an header to the request for the file.

Hope this helps!

Michele.