on my old ACS 4.1 installation I have custom TACACS+ services to support our Nokia (now Checkpoint) firewalls. Right now I have no chance to add such custom service to ACS5.
Does anyone know if this feature is on the roadmap and when it will be available?
Yes. It is also possible to use custom services. However, there is one bug related to authentication with custom services that will be fixed in the next patch for ACS 5.1 (patch 2). Issue is:CSCte16911
Authorization with custom services is working OK