ComputerCraft VoidNet Ping Test

local modem = peripheral.find("modem")
modem.open(123) -- Open channel 123 to listen for messages

while true do
    local _, _, sender, _, message = os.pullEvent("modem_message")
    if message == "ping" then
        print("Ping received from " .. sender)
        modem.transmit(123, 123, "pong")
    end
end