Thank you all for the quick response.

Unfortunately I'm still having some trouble.

This is what I have so far ( Its a lil messy but just for testing it should work )

This is based on the Client implementation:
http://cgit.osmocom.org/gr-osmosdr/tree/lib/rtl_tcp/rtl_tcp_source_f.cc#n275

#define COMM_SET_FREQ ((unsigned char) 0x01)
struct command{
        unsigned char cmd;
        unsigned int param;
};
    unsigned char cmds;
    int iFreq = 500000000;
    cmds = COMM_SET_FREQ;
    struct command cmd = {cmds, htonl(iFreq)};

answer = send(sConnect, (const char*)&cmd, sizeof(cmd), 0);

and the response is :

client accepted!
set freq -858993635
ll+, now 1
ll+, now 2
ll+, now 3

I'm sure I'm missing something I just don't know what.

Thanks