I have been trying to figure out how to setup nodemanagers on two computers in different locations.
Lets say one computer running Windows XP has IP address: xx.xx.26.70
and the other one running Linux has IP address: xx.xx.71.69

So I edited the first computer's nodemanager as follows

# This subsection defines the JAUS characteristics of the node
[JAUS]
SubsystemId: 1
NodeId: 1
Subsystem_Identification: OJSubsystem
Node_Identification: OJNode

# This subsection defines the interfaces and their options for component communication
[Component_Communications]
JAUS_OPC_UDP_Interface: true
OpenJAUS_UDP_Interface: true

# This subsection defines the interfaces and their options for node communication
[Node_Communications]
Enabled: true
JUDP_Interface: true
JUDP_IP_Address: xx.xx.26.70
#JAUS_OPC_UDP_Interface: true
#JAUS_OPC_UDP_IP_Address: xx.xx.26.70

# This subsection defines the interfaces and their options for subsystem communication
[Subsystem_Communications]
Enabled: true
JUDP_Interface: true
JUDP_IP_Address: xx.xx.71.69
#JAUS_OPC_UDP_Interface: true
#JAUS_OPC_UDP_IP_Address:xx.xx.26.1

But when I run the manager, it only terminates saying

OpenJAUS Node Manager Version 3.3.0b (SEPT 2, 2009)

Subsystem ADDED: OJSubsystem-1
Starting Subsystem Interfaces
ERROR (JudpInterface::openSocket:617): Could not open socket: xx.xx.71.69:3794
ERROR (MessageRouter::MessageRouter:85): Failed to construct JausSubsystemCommun
icationManager!
JudpInterface: Could not open socket

Terminating Program...
Shutting Down Node Manager...
Thank you for choosing OpenJAUS!

How can I resolve this problem?

You are configuring the node manager incorrectly. Are the two computers supposed to be different nodes on the same subsystem? or different nodes on different subsystems? Be sure to read through the JAUS reference architecture v3.3 documents to understand exactly what this means.

Assuming the machines are different nodes on the same subsystem, the correct configuration is like this:

On the machine with IP X.X.71.69, configure the Node Communications as follows:
[Node_Communications]
Enabled: true
JUDP_Interface: true
JUDP_IP_Address: xx.xx.71.69
#JAUS_OPC_UDP_Interface: true
#JAUS_OPC_UDP_IP_Address: xx.xx.71.69

On the machine with IP X.X.26.70 configure the node communications like this:
[Node_Communications]
Enabled: true
JUDP_Interface: true
JUDP_IP_Address: xx.xx.26.70
#JAUS_OPC_UDP_Interface: true
#JAUS_OPC_UDP_IP_Address: xx.xx.26.70

Make sure each node manager configuration has the same SubsystemId number, but DIFFERENT NodeId numbers. Also make sure the Subsystem Communications is set Enabled to false.