Here is documentation on what parameters are required for the Distributed Authentication filter to work:
1 Documentation, including javadocs https://confluence.ucdavis.edu/confluence/download/attachments/1071/distauthfilterdocumentation.zip?version=1
2 Technical documenation on authentication strategy modifying Sakai code, including DistAuth filter information https://confluence.ucdavis.edu/confluence/download/attachments/1071/technicaldocsauth15.doc?version=2