Q:

illegal IP for socket? 

Is there an IP 0.0.0.0 for a socket?  or 48.0.0.0 for a socket? 

A:

I don't quite understand your question.  If you elaborate I'll edit this answer. 
Binding a listening socket to 0.0.0.0 makes it listen on all interfaces.  If you bind to a particular IP address (127.0.0.1, for a common example) you'll only listen on that one instance (in this case, the localhost loopback interface). 
You don't bind client sockets, you connect them.  In this case, I don't think you can connect to 0.0.0.0 (in any case, it wouldn't be very useful). 
I don't think there's anything special about 48.0.0.0.  It looks like it's owned by Prudential Insurance, actually. 
If this isn't the question you're asking, you need to edit your question to ask it properly.