Hi Mickael,
You need a program called "iiod" running on the Zedboard. This one uses the port 30431.
The simplest way to get it is to update the operating system. See http://wiki.analog.com/resources/tools-software/linux-software/zynq_images#staying_up_to_date
Alternatively, if you really don't want to update the system you can compile libiio + iiod manually for your Zedboard:
What is libiio? [Analog Devices Wiki]
Regards,
Paul