http://docs.oracle.com/javase/tutorial/networking/datagrams/clientServer.html
All you need ^^
It's safe, it's streightforward, you wont need to over-complicate yourself with TCP procedures, and you wont be afraid of syn ACK packet floods :P (before you say smth regarding UDP flood, you'll get flooded with udp on standard ports like services 0 and 80, if you open a obscure one it wont affect anything)
Also, a good thing to it is, you dont need to maintain connections, each connection stands tll all data is written and flushed out :P So you wont need another server to maintain connections, that is vulnerable to attack :P. No master no slaves, just short and efficient connections.
PS: it supports Selectors, and nio Channels :P