The logical volume manager is a mechanism used by the Linux system to manage hard disk partitions. It is theoretically strong. The original intention of its creation is to solve the defect that the hard disk device is not easy to modify the partition size after the partition is created. Although it is theoretically feasible to force a traditional hard disk partition to expand or shrink, it may cause data loss. The LVM technology adds a logical layer between the hard disk partition and the file system. It provides an abstract volume group that can combine multiple hard disks. In this way, users do not need to care about the underlying structure and layout of the physical hard disk device, and can realize dynamic adjustment of hard disk partitions.
The iptables service refers to the policy entries used to process or filter traffic as rules. Multiple rules can form a rule chain, and the rule chain is classified according to different packet processing locations, as follows:
Process data packets before routing (PREROUTING);
process incoming data packets (INPUT);
process outgoing data packets (OUTPUT);
process forwarded data packets (FORWARD);
process data packets after routing (POSTROUTING) .
