use SOAP::Lite;

my $client = SOAP::Lite
        ->uri('http://localhost/Service')
        ->proxy('http://localhost/web-service');

my $auth = $client->login( 'username', 'password' );
exit 1 if $auth->fault != 0;

my $header = SOAP::Header->name( 'auth' => $auth->result );
my $response = $client->private_method( $header );


##</code><code>##

use SOAP::Lite;

my $client = SOAP::Lite
        ->service('http://localhost/Service.wsdl');

my $auth = $client->login( 'username', 'password' );
exit 1 if $auth->fault != 0;

my $header = SOAP::Header->name( 'auth' => $auth->result );
my $response = $client->private_method( $header );


##</code><code>##

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance" xmlns:xsd="http://www.w3.org/1999/XMLSchema">
  <SOAP-ENV:Body>
    <namesp3:private_method xmlns:namesp3="Service">
      <auth xsi:type="xsd:string">aeee24d36fc6107947b0d7b5af8aff41</auth>
    </namesp3:private_method>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>