Some of the socket tests require an echo server runing locally.
You can either compile and run the provided tests/echo-server.c
or enabled the echo services in (x)inetd.
Note: on Darwin, this can be achieved by uncommenting the echo
 service in /etc/inetd.conf and running:
   sudo xinetd -dontfork -inetd_compat)
Otherwise, set iolib-tests:*echo-address* and iolib-test:*echo-port*
appropriately if you want to point the echo tests somewhere else.