nodemcu-firmware/docs/en/modules/net.md

net Module

Constants

net.TCP, net.UDP

net.createConnection()

Creates a client.

Syntax

net.createConnection(type, secure)

Parameters

• type net.TCP or net.UDP
• secure 1 for encrypted, 0 for plain

Returns

net.socket sub module

Example

net.createConnection(net.UDP, 0)

See also

net.createServer()

net.createServer()

Creates a server.

Syntax

net.createServer(type, timeout)

Parameters

• type net.TCP or net.UDP
• timeout for a TCP server timeout is 1~28'800 seconds (for an inactive client to be disconnected)

Returns

net.server sub module

Example

net.createServer(net.TCP, 30) -- 30s timeout

See also

net.createConnection()

net.server Module

net.server:close()

Closes the server.

Syntax

net.server.close()

Parameters

none

Returns

nil

Example

-- creates a server
sv = net.createServer(net.TCP, 30)
-- closes the server
sv:close()

See also

net.createServer()

net.server:listen()

Listen on port from IP address.

Syntax

net.server.listen(port,[ip],function(net.socket))

Parameters

• port port number
• ip IP address string, can be omitted
• function(net.socket) callback function, pass to caller function as param if a connection is created successfully

Returns

nil

Example

 -- 30s time out for a inactive client
sv = net.createServer(net.TCP, 30)
-- server listens on 80, if data received, print data to console and send "hello world" back to caller
sv:listen(80, function(c)
	c:on("receive", function(c, pl) 
		print(pl)
	end)
	c:send("hello world")
end)

See also

net.createServer()

net.socket Module

net.socket:close()

Closes socket.

Syntax

close()

Parameters

none

Returns

nil

See also

net.createServer()

net.socket:connect()

Connect to a remote server.

Syntax

connect(port, ip|domain)

Parameters

• port port number
• ip IP address or domain name string

Returns

nil

See also

net.socket:on()

net.socket:dns()

Provides DNS resolution for a hostname.

Syntax

dns(domain, function(net.socket, ip))

Parameters

• domain domain name
• function(net.socket, ip) callback function. The first parameter is the socket, the second parameter is the IP address as a string.

Returns

nil

Example

sk = net.createConnection(net.TCP, 0)
sk:dns("www.nodemcu.com", function(conn, ip) print(ip) end)
sk = nil

See also

net.createServer()

net.socket:on()

Register callback functions for specific events.

Syntax

on(event, function())

Parameters

• event string, which can be "connection", "reconnection", "disconnection", "receive" or "sent"
• function(net.socket[, string]) callback function. The first parameter is the socket. If event is "receive", the second parameter is the received data as string.

Returns

nil

Example

sk = net.createConnection(net.TCP, 0)
sk:on("receive", function(sck, c) print(c) end )
sk:connect(80,"192.168.0.66")
sk:on("connection", function(sck,c)
    -- Wait for connection before sending.
    sk:send("GET / HTTP/1.1\r\nHost: 192.168.0.66\r\nConnection: keep-alive\r\nAccept: */*\r\n\r\n")
end)

See also

net.createServer()

net.socket:send()

Sends data to server.

Syntax

send(string, function(sent))

Parameters

• string data in string which will be sent to server
• function(sent) callback function for sending string

Returns

nil

Note

Multiple consecutive send() calls aren't guaranteed to work (and often don't) as network requests are treated as separate tasks by the SDK. Instead, subscribe to the "sent" event on the socket and send additional data (or close) in that callback. See #730 for an example and explanation.

See also

net.socket:on()

net.dns Module

net.dns.getdnsserver()

Gets the IP address of the DNS server used to resolve hostnames.

Syntax

net.dns.getdnsserver(dns_index)

Parameters

dns_index which DNS server to get (range 0~1)

Returns

IP address (string) of DNS server

Example

print(net.dns.getdnsserver(0)) -- 208.67.222.222
print(net.dns.getdnsserver(1)) -- nil

net.dns.setdnsserver("8.8.8.8", 0)
net.dns.setdnsserver("192.168.1.252", 1)

print(net.dns.getdnsserver(0)) -- 8.8.8.8
print(net.dns.getdnsserver(1)) -- 192.168.1.252

See also

net.dns:setdnsserver()

net.dns.resolve()

Resolve a hostname to an IP address. Doesn't require a socket like net.socket.dns().

Syntax

net.dns.resolve(host, function(ip))

Parameters

• host hostname to resolve
• function(sk, ip) callback called when the name was resolved. Don't use sk, it's a socket used internally to resolve the hostname.

Returns

nil

Example

net.dns.resolve("www.google.com", function(sk, ip)
    if (ip == nil) then print("DNS fail!") else print(ip) end
end)

See also

net.socket:dns()

net.dns.setdnsserver()

Sets the IP of the DNS server used to resolve hostnames. Default: resolver1.opendns.com (208.67.222.222). You can specify up to 2 DNS servers.

Syntax

net.dns.setdnsserver(dns_ip_addr, dns_index)

Parameters

• dns_ip_addr IP address of a DNS server
• dns_index which DNS server to set (range 0~1). Hence, it supports max. 2 servers.

Returns

nil

See also

net.dns:getdnsserver()