Description:
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The radlib.c:rad_init_send_request() function does
sin.sin_addr.s_addr = INADDR_ANY;
It would make sense to implement an option through which one could specify the outgoing IP address for the RADIUS request.

This is particularly relevant in this setting because RADIUS servers customarily restrict address per client IP address. 

If there was a way to pass a custom address with the request, one could add several IP address aliases to the same web server in order for different PHP scripts to do AAA on the same server, distinguished by the address of each request.