Secure channel switch

--I assume the modem is on the top
local modem = peripheral.wrap("top")
local channel = 1
modem.open(channel)



--Put your networking things here


local newChannel = math.random(1, 65535)
modem.transmit(actualChannel, actualChannel, "#/switch#")
modem.transmit(actualChannel, actualChannel, tostring(newChannel))
modem.close(actualChannel)
modem.open(newChannel)
local actualChannel = newChannel

--On the receiving computer

while true do
 local messageT = {os.pullEvent("modem_message")}
 if messageT[4] == "#/switch#" then
  local messageS = {os.pullEvent("modem_message")}
  local newChannel = tonumber(messageS[4])
  modem.close(actualChannel)
  modem.open(newChannel)
  actualChannel = newChannel
 end
end