def network_route_add(network, nat_server_ip)
      raise "ERROR: invalid nat_server_ip : '#{nat_server_ip}'" unless valid_ipv4?(nat_server_ip)
      raise "ERROR: invalid CIDR network : '#{network}'" unless valid_ipv4_cidr?(network)
      true
    end
def network_route_add(network, nat_server_ip)
      raise "ERROR: invalid nat_server_ip : '#{nat_server_ip}'" unless valid_ipv4?(nat_server_ip)
      raise "ERROR: invalid CIDR network : '#{network}'" unless valid_ipv4_cidr?(network)
      true
    end
Add route to network through NAT server

 Will not add if route already exists

 === Parameters
 network(String):: target network in CIDR notation
 nat_server_ip(String):: the IP address of the NAT "router"

 === Raise
 StandardError:: Route command fails

 === Return
 result(True):: Always returns true