I strained my own home made yoghurt to make this kind of cheese. There are two stages to labneh. You can either strain it for about a day to achieve a paste like consistency which is good for dips and mezzes, or go for longer to get to a cream cheese which can be shaped into balls and stored under olive oil.
500 g home made or rich, Greek style yoghurt; about half a teaspoon of fine salt
Mix the salt into the yoghurt. You should add enough salt to be able to taste it against the acidity of the yoghurt. Line another bowl with muslin and scoop the yoghurt into this. Pull up the cloth and tie up the top.
You need to fabricate some kind of hanging device (I used a coat hanger under a plant stand) and suspend the yoghurt over a bowl.
To get to the paste stage hang the labneh for 24 hours then remove from the muslin and refrigerate. For a denser consistency strain for 24 or 36 hours more.
Remove the labneh from the cloth, shape into balls laid out on a tray and refrigerate uncovered for 12 hours more to dry out.
Coat the balls in olive oil then place in a sealable jar and cover completely with olive oil. They can then be refrigerated and used when needed, but make sure you bring them back up to room temperature before eating.