5.1.x

The possibility to bind on all IP addreses of a interface having ip-in = ip-out.
Now you can do it like that for each IP:
CONFIG proxy.config.http.server_ports STRING PORT:ip-in=X.X.X.1:ip-out=X.X.X.1  PORT:ip-in=X.X.X.2:ip-out=X.X.X.2 .... PORT:ip-in=X.X.X.254:ip-out=X.X.X.254 .... and so on.

The only issue is that if you have more than 3 x 254 IPs on the interface ATS does not bind at all (maybe the config string gets too big).