receiver.lua

local modem = peripheral.find("modem") or error("No modem found!", 0) -- checks for modem

write("Recieving Channel (0-65535): ") -- asks user for input

    recieveChannel = read()

    recieveChannelInt = tonumber(recieveChannel) -- defines the recieveChannel as an integer, as modem.open can only handle integer input.

    print("Opening channel " .. recieveChannelInt .. "...")

    modem.open(recieveChannelInt)

    print("Channel " .. recieveChannelInt .. " open.")
    while true do
    local event, side, channel, replyChannel, message, distance -- defines vars, the channel variable here is from the computer contacting us from a channel (x).
    repeat
        event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
    until channel == recieveChannelInt -- puts variables into event until the channel variable is equal to the recieving channels variable. This helps prevent spoofing and allows messages from a certain channel.
     print("Recieved a reply from " .. tostring(message))  -- prints a reply
end