#6924 validates the remote_addr setting to permit only a list of pipe-separated IP addresses. It's actually a regular expression according to our docs (http://theforeman.org/manuals/1.10/index.html#3.5.2ConfigurationOptions):

remote_addr

If Foreman is running behind Passenger or a remote load balancer, the IP of this load balance should be set here. This is a regular expression, so it can support several load balancers, i.e: (10.0.0.1|127.0.0.1) Default: 127.0.0.1

Although the example is a simple regexp with two IPs and the or expression, regexes can be far more complex. It might be used to permit a whole subnet (e.g. ^10.0.0.\d+$).