I am running a Plesk system. Pretty much every hack attempt I have seen so far (slapper, etc.) uses executable files in the /tmp directory. Is it possible to make the /tmp directory so that it does not allow executable files? Would this hurt or break anything? What would be the right chmod value to use to do this so that /tmp would still be world readable/writeable but not allow files to be executed? I have noticed that SSH writes agent files to /tmp that are executable. Would making the /tmp directory non-executable affect SSH?
