Netmask to CIDR in ruby

Question

I\'ve been using the ip-address gem and it doesn\'t seem to have the ability to convert from a netmask of the form

255.255.255.0 

into the

Answer 1

If you don't need to use ip-address gem, you can do this with the netaddr gem

require 'netaddr'

def to_cidr_mask(dotted_mask)
  NetAddr::CIDR.create('0.0.0.0/'+dotted_mask).netmask
end

to_cidr_mask("255.224.0.0") # => "/11"