LWIP IPv4 client and server example

This example shows how to send and receive IPv4 UDP datagrams using LWIP network library.

Shell commands

The following commands are available:

ifconfig: allows manual IPv4 address configuration.
client: sends UDP datagram to given IPv4 address.

Usage on BOARD=native

This instruction, using native board, utilize tap interface and allows communication between RIOT system and host Linux.

In the following sections we describe how to:

configure tap interface using RIOT tapsetup tool.
send data from the Linux host to the RIOT.
send data from the RIOT to the Linux host.

Network configuration

Create tap0 interface and tapbr0 using RIOT tapsetup tool. Commands should be executed on the Linux host:

$sudo ./dist/tools/tapsetup/tapsetup -c 1
$sudo ip addr add 192.168.100.100/24 dev tapbr0

Compile and manually configure IPv4 address on the RIOT.

$make all
$./bin/native64/lwip_ipv4.elf tap0
RIOT native interrupts/signals initialized.
TZ not set, setting UTC
RIOT native64 board initialized.
RIOT native hardware initialization complete.

main(): This is RIOT! (Version: 2024.04-devel-2705-g39b6f-examples-lwip_ipv4)

> ifconfig add ET0 192.168.100.11/24
ifconfig add ET0 192.168.100.11/24
> ifconfig
ifconfig
Iface ET0 HWaddr: 8e:9d:7d:a1:fd:cd Link: up State: up
        Link type: wired
        inet addr: 192.168.100.11 mask: 255.255.255.0 gw: 0.0.0.0
>

Check connectivity from the Linux host machine to the RIOT:

$ping 192.168.100.11
PING 192.168.100.11 (192.168.100.11) 56(84) bytes of data.
64 bytes from 192.168.100.11: icmp_seq=1 ttl=255 time=0.240 ms
64 bytes from 192.168.100.11: icmp_seq=2 ttl=255 time=0.210 ms
...

RIOT LWIP IPv4 server

The server starts automatically on the RIOT:

main(): This is RIOT! (Version: 2024.04-devel-3275-gab2302-examples-lwip_ipv4)
{"IPv4 addresses": ["192.168.100.11"]}
Server started.
>

Send UDP datagram from the Linux host using nc tool:

$ nc -u 192.168.100.11 4444
Msg from Linux
Msg from Linux

Observe results on the RIOT:

main(): This is RIOT! (Version: 2024.04-devel-3275-gab2302-examples-lwip_ipv4)
{"IPv4 addresses": ["192.168.100.11"]}
Server started.
> Received 15 bytes - Msg from Linux

RIOT LWIP IPv4 client

Run server on the Linux host using nc tool:

$ nc -ul -p 4444

Send UDP datagram from the RIOT:

> client 192.168.100.100 4444 Msg_from_RIOT
client 192.168.100.100 4444 Msg_from_RIOT
>

Observe result on the Linux host:

$nc -ul -p 4444
Msg_from_RIOT