How to crash server
Teach how crash server fast please!
You would either have to:
• send it more information than it can handle (not always the effective since servers these days always allocate a thread per client).
• send it more clients than it can handle (threads take up system resources, will lock up a single server if it's dumb to accept any client) This is the basis for SYN attacks but this is largely mitigated by forcing the client to partially complete the TCP handshake before the server agrees to hold the socket open.
• disrupt it internally by making it crash or something (tampering with user input)
• different point of attack, other programs may be vulnerable that you might use to crash the server
Such information is publicly available, mostly for public knowledge and building better security.
But don't try to perform on real systems! You will either: crash your own computer, crash someone else's, get charged with serious offenses or even jail time.