Title: X Through The Firewall, And Other Application Relays 
Authors: G. Winfield Treese  Alec Wolman    
File name:pubdocfirewallsTreese-Wolman-X_Firewalls.ps.Z  
File size: 145265bytes  

Abstract: Organizations often impose an administrative
security policy when they connect to other organizations on a
public network such as the Internet.  Many applications have
their own notions of security, or they simply rely on the
security of the underlying protocols. Using the X Window System
as a case study, we describe some techniques for building
application-specific "relays" that allow the use of applications
across organizational boundaries. In particular, we focus on
analyzing administrative and application-specific security
policies to construct solutions that satisfy the security
requirements while providing the necessary functions of the
applications.