====== IPTables ======

iptables is a user-space utility program that allows a system administrator to configure the tables[2] provided by the Linux kernel firewall (implemented as different Netfilter modules) and the chains and rules it stores. Different kernel modules and programs are currently used for different protocols; iptables applies to IPv4, ip6tables to IPv6, arptables to ARP, and ebtables to Ethernet frames.

iptables requires elevated privileges to operate and must be executed by user root, otherwise it fails to function. On most Linux systems, iptables is installed as /usr/sbin/iptables and documented in its man pages, which can be opened using man iptables when installed. It may also be found in /sbin/iptables, but since iptables is more like a service rather than an "essential binary", the preferred location remains /usr/sbin.

The term iptables is also commonly used to inclusively refer to the kernel-level components. x_tables is the name of the kernel module carrying the shared code portion used by all four modules that also provides the API used for extensions; subsequently, Xtables is more or less used to refer to the entire firewall (v4, v6, arp, and eb) architecture.

iptables superseded ipchains; and the successor of iptables is nftables.

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[[Ubuntu:IPTables:Basic commands|Basic commands]]

[[Ubuntu:IPTables:Basic Firewall|Basic Firewall]]

[[Ubuntu:IPTables:Block Facebook|Block Facebook]]

[[Ubuntu:IPTables:Block SSH brute force attacks|Block SSH brute force attacks]]

[[Ubuntu:IPTables:Configure Port Knocking|Configure Port Knocking]]

[[Ubuntu:IPTables:Create a VPN kill switch|Create a VPN kill switch]]

[[Ubuntu:IPTables:DNS query limiting|DNS query limiting]]

[[Ubuntu:IPTables:Firewall|Firewall]]

[[Ubuntu:IPTables:Firewall Script|Firewall Script]]

[[Ubuntu:IPTables:Forward ports|Forward ports]]

[[Ubuntu:IPTables:Implement a basic firewall|Implement a basic firewall]]

[[Ubuntu:IPTables:IPv6 Support|IPv6 Support]]

[[Ubuntu:IPTables:Log firewall messages to a separate file|Log firewall messages to a separate file]]

[[Ubuntu:IPTables:NAT how to enable PPTP in newer Debian/Ubuntu/Mint Kernels|NAT how to enable PPTP in newer Debian/Ubuntu/Mint Kernels]]

[[Ubuntu:IPTables:Rate limiting|Rate limiting]]

[[Ubuntu:IPTables:Reset|Reset]]

[[Ubuntu:IPTables:Save IPTable rules|Save IPTable rules]]

[[Ubuntu:IPTables:Share an IP address between clients|Share an IP address between clients]]

[[Ubuntu:IPTables:Share an IP address between servers|Share an IP address between servers]]

[[Ubuntu:IPTables:Test the firewall|Test the firewall]]

[[Ubuntu:IPTables:Troubleshooting iptables|Troubleshooting iptables]]

[[Ubuntu:IPTables:Verify the iptables kernel module is loaded|Verify the iptables kernel module is loaded]]

[[Ubuntu:IPTables:Verify the iptables package is installed|Verify the iptables package is installed]]