centos7.3输入所有有关 firewall-cmd 命令将会出现
Job for firewalld.service failed because a timeout was exceeded.See "systemctl status firewalld.service" and "journalctl -xe" for details.
的错误
原因：centos7 里面装了Python2.7 和 Python(其他) 两个版本，执行firewall-cmd 系列的命令的时候回运行Python文件结果Python文件的头
#!/usr/bin/python
都不会再python2.7 里面运行，
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顺便说一句，出现ImportError: No module named ....这种错误的时候，
第一检查出错的文件的头，是不是系统默认的Python，一般centos默认Python2.7，不是的话改成#!/usr/bin/python2.7。
第二，用pip安装相应的模块
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解决办法：
1) 命令窗口输入
sudo systemctl status firewalld.service
得到
● firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: failed (Result: timeout) since Sat 2017-02-18 19:36:21 PST; 34min ago
Docs: man:firewalld(1)
Process: 9677 ExecStart=/usr/sbin/firewalld --nofork --nopid $FIREWALLD_ARGS (code=exited, status=0/SUC
Main PID: 9677 (code=exited, status=0/SUCCESS)
Feb 18 19:34:49 Reksio systemd[1]: Starting firewalld - dynamic firewall daemon...
Feb 18 19:36:19 Reksio systemd[1]: firewalld.service: Start operation timed out. Terminating.
Feb 18 19:36:21 Reksio systemd[1]: Failed to start firewalld - dynamic firewall daemon.
Feb 18 19:36:21 Reksio systemd[1]: firewalld.service: Unit entered failed state.
Feb 18 19:36:21 Reksio systemd[1]: firewalld.service: Failed with result 'timeout'
2) 再输入
sudo /usr/sbin/firewalld --nofork --nopid --debug 10
即可找到 debug
3)编辑： vim /usr/sbin/firewalld 将头改为 2.7 即可
看下图
成功解决！！！