The Taut-Line Hitch is a hitch based knot that is adjustable and should not slip when tied properly and is placed under tension. If you are staking down the lines for your tent or dining fly, this is the perfect knot to use.
Taut-Line Hitch
Pass the tail end
Around
The standing end.
Pass it around
again
Tuck it in beside the first turn and pull it tight
Continue around
And tie a half hitch
To make a Taut-Line Hitch