root@OpenWrt:~# iperf -c 192.168.1.1 -p 1234
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 1234
TCP window size: 20.8 KByte (default)
------------------------------------------------------------
[  3] local 192.168.1.241 port 35326 connected with 192.168.1.1 port 1234
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.7 sec  2.13 MBytes  1.66 Mbits/sec
root@OpenWrt:~# iperf -c -u 192.168.1.1 -p 1234
------------------------------------------------------------
Client connecting to 192.168.1.1, UDP port 1234
Sending 1470 byte datagrams
UDP buffer size:  160 KByte (default)
------------------------------------------------------------
[  3] local 192.168.1.241 port 44830 connected with 192.168.1.1 port 1234
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  56.0 GBytes  48.0 Gbits/sec
[  3] Sent 893 datagrams
read failed: Connection refused
[  3] WARNING: did not receive ack of last datagram after 1 tries.
root@OpenWrt:~#