You need to be more specific. There are two different approaches that I know of, which one are you asking about, exactly?
In the 1st approach, a proxy/LB injects the client info directly into the headers of the final ACK of the TCP handshake, and the 1st data packet. I don't know any way to access this data with standard socket APIs.
In the 2nd approach, a proxy/LB uses the
PROXY protocol to send the client info after the TCP handshake and before the 1st data packet. This is very easy to implement with standard socket APIs, but requires prior knowledge that such info is going to be sent (unless you peek the socket to discover the protocol dynamically).
In the 1st approach, a proxy/LB injects the client info directly into the headers of the final ACK of the TCP handshake, and the 1st data packet. I don't know any way to access this data with standard socket APIs.
In the 2nd approach, a proxy/LB uses the
PROXY protocol to send the client info after the TCP handshake and before the 1st data packet. This is very easy to implement with standard socket APIs, but requires prior knowledge that such info is going to be sent (unless you peek the socket to discover the protocol dynamically).