Looking for security guidelines

[Joe Simpson]

I am looking for recommendations for security guidlines for unix boxes.
 
I am specialized interest in security for ULTRIX, but would also like
more general references.
 
I am aware of Charles Hedrick's very fine intro to TCP/IP and TCP/IP
admin.  I also have Russell L. Brand's "Coping with the Threat of
Computer Security Incidents".
 
Thanks for any leads to either commercial texts or ftp'able documents.