If Alfresco is configured with Kerberos Auth and SSO, the work around described in
ALF-21521 is no longer working in Alfresco 5.2 to allow external users to login on e.g. WebDAV.
Unfortunately there is no acceptable configuration to have SSO and basic auth / digest auth or any configurable fall back auth for external users on the protocol adapters like webdav. Even internal users are not able to connect webdav if not comming from the internal network because MS Kerberos is not designed for external access.