The nginx 1.9 comes with built-in tcp proxing. However, I'm facing the port exhaustion problem on this. Unlike HTTP, it is quite common for TCP servers to hold a lot of socket connections while each connection is nearly idle (e.g. push server). I tuned nginx but the concurrent tcp connections is limited to ~60k as there are no more ports available, while as a matter of fact, I do have multiple network interfaces and abundant free IPs.

It is suggested that the "proxy_bind" directive of Module ngx_stream_proxy_module should accept multiple IPs, so that the nginx can use multiple network interfaces to connect the back end servers to overcome the current ~60k limitation caused by port exhaustion.