g++ -Wall -ansi -pedantic -g client.cpp sockets.cpp sockets.h -o client
g++ -Wall -ansi -pedantic -g tracker.h tracker.cpp sockets.cpp sockets.h
-o tracker

./tracker

./client 127.0.0.1

(add more clients)
./client 127.0.0.1
./client 127.0.0.1
./client 127.0.0.1

so trackers maintaining the tracking list
and clients are able to receive it upon entry