ELB supports layer-4 load balancing, which would just multiplex inbound TCP connections (with an added bonus of offloading TLS), but I'm concerned about losing client IP addresses. ELB actually has a way to address this with HAProxy's PROXY protocol: http://www.haproxy.org/download/1.6/doc/proxy-protocol.txt

However, I haven't found a place for setting up the PROXY protocol support in undertow. Has anyone done this? Is there a way I should be going about it?