Post by nelsonelias on Feb 20, 2024 2:52:28 GMT -5
IPtables is a free firewall application in Linux that allows setting up private rules to control access and increase security . When using a server, a firewall is one of the important tools to help you prevent invalid access. For Linux distributions like Ubuntu, Fedora, CentOS… you can find the built-in firewall tool IPtables . What are the components that make up IPtables? Let Mat Bao answer this question for you! What is IPtables? It is pre-installed in Linux versions IPtables is pre-installed in Linux versions IPtables is a firewall application available on Linux. IPtables Linux firewall allows users to set access rights to selectively control traffic on the server. What are the components of IPtables? What is IPtables? Processing order of tables and chains in packet processing flow Processing order of tables and chains in packet processing flow Essentially, IPtables is just a command line interface to interact with the netfilter framework's packet filtering.
IPtables ' packet filtering mechanism consists of three components: Tables, Chains and Targets. What are tables in IPtables? The table is used by IPtables to define rules for packets. In it, there are the following Tables. Filter Table As one of the tables most used by IPtables , Filter Table will decide whether a packet goes to the intended destination or whether the packet's request is denied. NAT Table To use NAT (Network Address Translation) rules, the NAT Table will be responsible for editing the source (source IP) or destination (destination IP) of the packet when implementing the NAT Loan Phone Number List mechanism. Mangle Table Allows editing packet headers, values of TTL, MTU, Type of Service fields. Raw Table IPtables is a stateful firewall with packets inspected relative to state. For example the packet can be part of a new connection or part of an existing connection. Raw Table will help you work with packets before the kernel starts checking the status and may exclude some packets from tracking due to system performance issues. Security Table Some kernels may additionally support Security Table, which is used by SELinux to establish security policies.
Chains Chains are created in a certain number for each Table, helping to filter packets at different points. Chain PREROUTING exists in Nat Table, Mangle Table and Raw Table, the rules in the chain will be executed as soon as the packet arrives at the network interface. Chain INPUT is only available in the Mangle Table and Nat Table with rules being executed immediately before the packet encounters the process. Chain OUTPUT exists in Raw Table, Mangle Table and Filter Table, whose rules are executed after the packet is created by the process. Chain FORWARD exists in the Manle Table and Filter Table, which have rules enforced for packets routed through the current host. Chain POSTROUTING exists only at the Manle Table and Nat Table with rules that are enforced when the packet leaves the network interface.
IPtables ' packet filtering mechanism consists of three components: Tables, Chains and Targets. What are tables in IPtables? The table is used by IPtables to define rules for packets. In it, there are the following Tables. Filter Table As one of the tables most used by IPtables , Filter Table will decide whether a packet goes to the intended destination or whether the packet's request is denied. NAT Table To use NAT (Network Address Translation) rules, the NAT Table will be responsible for editing the source (source IP) or destination (destination IP) of the packet when implementing the NAT Loan Phone Number List mechanism. Mangle Table Allows editing packet headers, values of TTL, MTU, Type of Service fields. Raw Table IPtables is a stateful firewall with packets inspected relative to state. For example the packet can be part of a new connection or part of an existing connection. Raw Table will help you work with packets before the kernel starts checking the status and may exclude some packets from tracking due to system performance issues. Security Table Some kernels may additionally support Security Table, which is used by SELinux to establish security policies.
Chains Chains are created in a certain number for each Table, helping to filter packets at different points. Chain PREROUTING exists in Nat Table, Mangle Table and Raw Table, the rules in the chain will be executed as soon as the packet arrives at the network interface. Chain INPUT is only available in the Mangle Table and Nat Table with rules being executed immediately before the packet encounters the process. Chain OUTPUT exists in Raw Table, Mangle Table and Filter Table, whose rules are executed after the packet is created by the process. Chain FORWARD exists in the Manle Table and Filter Table, which have rules enforced for packets routed through the current host. Chain POSTROUTING exists only at the Manle Table and Nat Table with rules that are enforced when the packet leaves the network interface.