The Outposter, By Gordon R Dickson (Pinnacle Books, 1982).

Trapped...The Outposters, a token band of specially trained experts, were given the task of guiding the exiled colonists in their harsh new environment and protecting them from the treachery of the enemy Meda V'Dans.

But the problems seemed insurmountable. For Earth was indifferent to her superfluous population and supply lines ran thin. The colonists were considered disposable "garbage."

But one young Outposter, Mark Ten Roos, had an old score to settle with the Meda V'Dans. Years ago they had killed his parents and now they had crippled his adopted father.

His plan was a daring challenge to the system. But could he change the odds...?