調試Cent OS 7.5的系統的IPerf，發現server端，無法打印出來的間隔接受率等信息，client也報錯，報錯顯示如下
[root@localhost ~]# iperf -u -c 192.168.108.61 -i1 -t9999999999 -b 3M -l 1200
------------------------------------------------------------
Client connecting to 192.168.108.61, UDP port 5001
Sending 1200 byte datagrams
UDP buffer size: 10.0 MByte (default)
------------------------------------------------------------
[ 3] local 192.168.108.15 port 56937 connected with 192.168.108.61 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 1.0 sec 360 KBytes 2.95 Mbits/sec
[ 3] 1.0- 2.0 sec 364 KBytes 2.99 Mbits/sec
[ 3] 2.0- 3.0 sec 366 KBytes 3.00 Mbits/sec
[ 3] 3.0- 4.0 sec 364 KBytes 2.99 Mbits/sec
[ 3] 4.0- 5.0 sec 366 KBytes 3.00 Mbits/sec
[ 3] 5.0- 6.0 sec 364 KBytes 2.99 Mbits/sec
[ 3] 6.0- 7.0 sec 366 KBytes 3.00 Mbits/sec
[ 3] 7.0- 8.0 sec 364 KBytes 2.99 Mbits/sec
[ 3] 8.0- 9.0 sec 366 KBytes 3.00 Mbits/sec
[ 3] 9.0-10.0 sec 364 KBytes 2.99 Mbits/sec
[ 3] 10.0-11.0 sec 366 KBytes 3.00 Mbits/sec
[ 3] 11.0-12.0 sec 364 KBytes 2.99 Mbits/sec
[ 3] 12.0-13.0 sec 366 KBytes 3.00 Mbits/sec
[ 3] 13.0-14.0 sec 364 KBytes 2.99 Mbits/sec
[ 3] 14.0-15.0 sec 366 KBytes 3.00 Mbits/sec
^C[ 3] 0.0-15.1 sec 5.39 MBytes 2.99 Mbits/sec
[ 3] Sent 4734 datagrams
read failed: No route to host
[ 3] WARNING: did not receive ack of last datagram after 5 tries.
server顯示異常：
經過長久分析發現是server端的 防火牆導致的，關閉防火牆以後即可避免
關閉防火牆：
[root@localhost data1]#
[root@localhost data1]# firewall-cmd --state
running ------------------查看顯示狀態
[root@localhost data1]# systemctl stop firewalld.service ---關閉防火牆
[root@localhost data1]# firewall-cmd --state
not running ------------已關閉
[root@localhost data1]#
再次運行工具，查看正常：
[root@localhost data1]# iperf -s -u -i1
------------------------------------------------------------
Server listening on UDP port 5001
Receiving 1470 byte datagrams
UDP buffer size: 10.0 MByte (default)
------------------------------------------------------------
[ 3] local 192.168.108.61 port 5001 connected with 192.168.108.15 port 50714
[ ID] Interval Transfer Bandwidth Jitter Lost/Total Datagrams
[ 3] 0.0- 1.0 sec 366 KBytes 3.00 Mbits/sec 0.008 ms 0/ 312 (0%)
[ 3] 1.0- 2.0 sec 367 KBytes 3.00 Mbits/sec 0.019 ms 0/ 313 (0%)
[ 3] 2.0- 3.0 sec 366 KBytes 3.00 Mbits/sec 0.011 ms 0/ 312 (0%)
[ 3] 3.0- 4.0 sec 367 KBytes 3.00 Mbits/sec 0.022 ms 0/ 313 (0%)
[ 3] 4.0- 5.0 sec 366 KBytes 3.00 Mbits/sec 0.004 ms 0/ 312 (0%)
[ 3] 5.0- 6.0 sec 367 KBytes 3.00 Mbits/sec 0.004 ms 0/ 313 (0%)
[ 3] 6.0- 7.0 sec 366 KBytes 3.00 Mbits/sec 0.015 ms 0/ 312 (0%)
[ 3] 7.0- 8.0 sec 367 KBytes 3.00 Mbits/sec 0.015 ms 0/ 313 (0%)