Ruby/Network/ping

require "ping"
puts "Pong!" if Ping.pingecho("localhost", 5)

require "rubygems"
require "net/ping"
if Net::PingTCP.new("http://www.google.ru/", 80).ping
  puts "Pong!"
else
  puts "No response"
end

require "ping"
puts "Pong!" if Ping.pingecho("http://www.google.ru/", 5)

which is available as a gem with gem install net-ping
 
require "rubygems"
require "net/ping"
if Net::PingExternal.new("http://www.google.ru/").ping
  puts "Pong!"
else
  puts "No response"
end