I need to route TCP and UDP packets via a proxy server, at layer 4 (i.e. without TLS termination, for TCP packets). The destination address for all packets is not fixed. In other words, the routing needs to be dynamic and the destination for each packet can be determined based on destination hostname/IP in the packet. So, TCP/TLS packets can be routed based on SNI (in TLS ClientHello) because all TCP in my case is TLS. However, UDP packets cannot be, as SNI is typically for TCP and its equivalent does not seem to be present in UDP.

I was looking at envoy proxy's DestinationIPInput filter (https://www.envoyproxy.io/docs/envoy...ching_listener) to cater to this problem but it is based on HAProxy Proxy protocol (https://www.envoyproxy.io/docs/envoy...proxy-protocol), which doesn't seem to support UDP (https://www.haproxy.org/download/1.9...y-protocol.txt).

Is there a standard proxy protocol, using which a proxy server can determine the destination server address (and port) for UDP packets coming to it from a client (which can also send the packets in compliance with the same protocol) ? Will be good, if the same protocol can support TCP/HTTP proxying too.