Star Trek: Gateways, book 01 : One Small StepSusan Wright2001

Scattered throughout the galaxy are Gateways capable of transporting matter and energy across unfathomable distances. Left behind by a long-vanished civilization, these mysterious portals offer a means of exploration – or conquest – many times faster than warp travel. The technology responsible for the Gateways has been lost for at least ten millennia, but that doesn't mean it can't be found again...

Having defeated the hostile computer program guarding an abandoned Kalandan outpost, Kirk and his crew are exploring the artificial planetoid in hopes of discovering the secret of an ancient apparatus that has hurled the Starship Enterprise over nearly a thousand light years. Unfortunately, the reactivated Gateway has attracted the attention – and avarice – of various alien explorers, including a mysterious race who claim to be none other than the enigmatic Kalandans themselves!