The program is called Echoer, whose features are described below.

• Echoer takes as arguments a tcp port and a udp port to which it will listen to incoming connection requests and incoming udp packets, respectively: java Echoer

• Echoer is able to handle up to 7 outgoing tcp connections at the same time. By out-going connection, we mean the connection which this process initiated. Feel free to increase your limit to be more than 7.

• Echoer operates somewhat like a Unix shell. It keeps taking user's commands, at the same time watches incoming connection requests and data packets. When appropriate, Echoer prints out diagnostic information to standard output and then goes back to the prompt mode to accept user's inputs.

• below is a description of all commands Echoer handles, along with the description of associated actions :

o info: print out its IP address, host name, TCP (listening) port, UDP port. For example: IP address hostname udp port tcp port

192.168.0.3 (funny.cse.buffalo.edu)     4892           43444

o connect : try to establish a tcp connection to at port . For example connect 192.168.0.3 99999 both sides then report that the connection is indeed established.

• show: show all existing outgoing tcp connections in the following format: conn. ID | IP | hostname | local port | remote port

 1     | 192.168.0.1   | abc.cse.buffalo.edu  | 1234       | 1235
 2     | 192.168.0.2   | def.cse.buffalo.edu  | 1453       | 98234
 3     | 192.168.0.3   | ghi.cse.buffalo.edu  | 1233       | 09823
 4     | 192.168.0.4   | xyz.cse.buffalo.edu  | 1235       | 0823

o send : send to the connection whose id is . Here, is the entire text (including blank spaces) that follows the first argument. For example, send 3 Oh! This assignment is a piece of cake.

o sendto : send as a udp datagram to at .

o disconnect : disconnect the tcp connection whose id is .