The Demon Breed — James H. Schmitz

The bluish-grey torsos and powerful arms were enclosed by webbings of straps, holding tools and weapons. The bulging eyes on the big round heads were double-lensed..Seventy years before Parahuans came out of space to launch simultaneous attacks on a dozen worlds of the Hub. They lost the first round. Now they were back. And Nile had to stay alive long enough to get the message to the Federation's warships.