<?xml version="1.0"?>
<instances>
        ...
        <instance id="example" ... >
                ...
                <auths>
                        <auth module="tls_userlist">
                                <user user="sqlrclient1.firstworks.com"/>
                                <user user="sqlrclient2.firstworks.com"/>
                                <user user="sqlrclient3.firstworks.com"/>
                                <user user="sqlrclient4.firstworks.com"/>
                        <auth>
                </auths>
                ...
        </instance>
        ...
</instances>