Today i run iptables -F on a server, that blocked access to all ports. This was a Plesk server with firewall enabled through Plesk control panel.
This is because default policy is set to DROP all connections.
Before you run
Make sure default policy is set to allow. if it is set to DROP as shown below, you won’t be able to connect to server once firewall rules are flushed.
[root@u18953237 ~]# iptables -L -n | grep policy Chain INPUT (policy DROP) Chain FORWARD (policy DROP) Chain OUTPUT (policy DROP) [root@u18953237 ~]#