Recall that in a TCP handshake, a client first sends a SYN message

to a server. The server then sends a SYN$/$ACK message back to the client, and waits for the latter$$s

ACK. During this wait, the server has to remember the connection information $($client$/$server IP and

ports$),$ as well as the maximum segment size $($MSS$),$ the maximal size of the data a TCP packet may

contain, which is communicated by the client in its initial SYN$$s message. $($We assume here that

there are only $8$ possible choices for MSS$.)$ In other words, every TCP connection makes the server

allocate some memory during the wait for the client$$s final ACK message. This can be exploited for

a denial$-$of$-$service attack as follows: send lots of TCP SYN packets to the server, but never send the

final ACK messages. The server will then quickly run out of memory