Evaluation of Three Approaches for CORBA Firewall/NAT Traversal

			     Abstract 

Applications based on CORBA middleware usually have problems of 
multi-domain deployment due to restrictions for firewall traversal and NAT 
usage. Moreover, untill now there isn't a well-established, standardized 
solution for this problem which could be adopted by all ORBs. This compells 
application developers using CORBA to use proprietary solutions that 
sometimes do not properly address the access restrictions of the networks in 
which they are deployed (e.g. impossibility to open firewall ports). This 
work presents and compares three solutions for firewall/NAT traversal by 
CORBA-based distributed applications, each one suited for a specific 
situation, such as the possibility of open firewall ports or the possibility 
of start a TCP connection to the outside network. Each solution tries to 
explore the advantages of each situation and has been implemented and tested 
using three different ORBs.