Some DoS attacks can be avoided by applying vendor patches to affected software. For example, many vendors have patched their IP implementations to prevent intruders from taking advantage of the IP reassembly bugs. A few DoS attacks cannot be stopped, but their scope of affected areas can be constrained. TCP SYN flooding attack effects can be reduced or eliminated by limiting the number of TCP connections a system accepts and by shortening the amount of time a connection stays half open (that is, the time during which the TCP three-way handshake has been initiated but not completed). Typically, limiting the number.
