Another free REST API with city accurate information would be http://freegeoip.net Requests are fairly straight forward. You would use something like http://freegeoip.net/{format}/{ip_or_hostname} to geocode an IP address, where format can be csv, xml or json. Their website has all the details. [UPDATE:] FreeGeoIP.net was not continuously available in the past as a public service. The … Read more
Sinatra provides a request object, which is the interface to the client request data that you should be using. Using request.ip is the preferred method to find the client’s IP address: get “https://stackoverflow.com/” do “Your IP address is #{request.ip}” end
That’s Classless Inter-Doman Routing notation. The /24 means that the routing prefix of the subnet is 24 bits long, which means there’s ony 8 bits left for the subnet itself, i.e. 123.218.44.0 to 123.218.44.255
According to Reserved IP addresses there are 588,514,304 reserved addresses and since there are 4,294,967,296 (2^32) IPv4 addressess in total, there are 3,706,452,992 public addresses. And too many addresses in this post.