Attempts to use an IBM Rational product on a system protected by a firewall results in the error "FLEXlm error -96, Server node is down or not responding".
Cause #1: This issue is commonly cause by the firewall blocking specific port requests made by the IBM Rational License Server which in turn prevents the client system from obtaining a License Key.
Cause #2: FLEXlm error -96 indicates that the client can communicate with the lmgrd daemon, but not the rational, ibmratl vendor daemons.
Cause #3: The port for the rational, ibmratl vendor daemons is not opened on the firewall.
Resolving the problem
Solution #1: In order to check out licenses from the license server through a firewall, three ports need to be opened in the firewall for the lmgrd daemon and for the Rational vendor daemon. Review the installation guide for more details.
Solution #2: A port number has been specified for the vendor daemon, but the license server has not been restarted for the change to take effect since a new port was specified.
Ensure you restart the license server for changes to take effect.
Solution #3: Check with your local LAN administrator to ensure that the correct port on the firewall is opened for the rational and ibmratl vendor daemons.
To find out which port to open for the rational, ibmratl vendor daemons, open the license *.dat file, find the DAEMON line, and look for port=xxxx at the end of the DAEMON line.
VENDOR rational PORT=27001
VENDOR ibmratl PORT=27002
If there is no port number specified in the DAEMON line, you can add the port=XXXX at the end of it, where XXXX is a spare port number of your network configuration, and you need to open XXXX in firewall.
Solution #4: Opening the firewall port 1052 has also be reported as a solution to this issue.