centos7重啟iptables時失敗铛嘱，通過systemctl status iptables.service查看錯誤信息暖释，內(nèi)容如下所示：

# *systemctl status iptables.service

— iptables.service - IPv4 firewall with iptables

  Loaded: loaded (/usr/lib/systemd/system/iptables.service; enabled; vendor preset: disabled)

  Active: failed (Result: exit-code) since Wed 2018-01-10 05:11:42 EST; 4s ago

  Process: 3994 ExecStop=/usr/libexec/iptables/iptables.init stop (code=exited, status=0/SUCCESS)

  Process: 5236 ExecStart=/usr/libexec/iptables/iptables.init start (code=exited, status=1/FAILURE)

Main PID: 5236 (code=exited, status=1/FAILURE)

Jan 10 05:11:42 master.example.com systemd[1]: Starting IPv4 firewall with i....

Jan 10 05:11:42 master.example.com iptables.init[5236]: iptables: Applying fi...

Jan 10 05:11:42 master.example.com iptables.init[5236]: Error occurred at lin...

Jan 10 05:11:42 master.example.com iptables.init[5236]: Try `iptables-restore...

Jan 10 05:11:42 master.example.com iptables.init[5236]: [FAILED]

Jan 10 05:11:42 master.example.com systemd[1]: iptables.service: main proces...E

Jan 10 05:11:42 master.example.com systemd[1]: Failed to start IPv4 firewall....

Jan 10 05:11:42 master.example.com systemd[1]: Unit iptables.service entered....

Jan 10 05:11:42 master.example.com systemd[1]: iptables.service failed.

Hint: Some lines were ellipsized, use -l to show in full.

上面的錯誤是在啟動ipv4 firewall時失敗，可嘗試關(guān)閉firewalld服務(wù)在重啟iptables：

# service iptables save

#  systemctl stop firewalld  -- 關(guān)閉firewalld服務(wù)

#  systemctl disable  firewalld  --設(shè)置開機(jī)禁用firewalld

#  systemctl start iptables   -- 啟動iptables

#  systemctl status iptables --確認(rèn)iptables狀態(tài)

#  systemctl enable iptables  -- 設(shè)置iptables開機(jī)啟動

#  systemctl status firewalld  --確認(rèn)firewalld服務(wù)

除了使用上述的方法以外墨吓，啟動失敗的原因也可能是iptables的規(guī)則配置錯誤球匕。
可以check下/etc/sysconfig/iptables文件。