To open the firewall for the Rational Common Licensing license server, go to the Rational/common directory and double-click WinXPSP2.reg. This file imports the changes to the registry and opens the firewall for rational.exe and lmgrd.exe to use any ports.
If you did not use the default path (C:\Program Files\Rational\Common\) to install the Rational License Server, you must edit the WinXPSP2.reg file by replacing the C:\Program Files\Rational\Common in two locations in each line with the actual installation path.
Optionally, you can open the firewall for the IBM Rational License Server manually, as follows: