Co robi IPTABLES użycie. Konsola for iptables consist of some matching criteria and a target, a.

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Polecenie iptables

Wykonanie, użycie: System administration command. Configure netfilter filtering rules for kernels 2.4 and later. Rules for iptables consist of some matching criteria and a target, a result to be applied if the packet matches the criteria. The rules are organized into chains. You can use these rules to build a firewall, masquerade your local area network, or just reject certain kinds of network connections.

There are three built-in tables for iptables: one for network filtering (filter), one for Network Address Translation (nat), and the last for specialized packet alterations (mangle). Firewall rules are organized into chains, ordered checklists of rules that the kernel works through looking for matches. The filter table has three built-in chains: INPUT, OUTPUT, and FORWARD. The INPUT and OUTPUT chains handle packets originating from or destined for the host system. The FORWARD chain handles packets just passing through the host system. The nat table also has three built-in chains: PREROUTING, POSTROUTING, and OUTPUT. mangle has only two chains: PREROUTING and OUTPUT.

netfilter checks packets entering the system. After applying any PREROUTING rules, it passes them to the INPUT chain, or to the FORWARD chain if the packet is just passing through. Upon leaving, the system packets are passed to the OUTPUT chain and then on to any POSTROUTING rules. Each of these chains has a default target (a policy) in case no match is found. User-defined chains can also be created and used as targets for packets but do not have default policies. If no match can be found in a user-defined chain, the packet is returned to the chain from which it was called and tested against the next rule in that chain.

iptables changes only the rules in the running kernel. When the system is powered off, all changes are lost. You can use the iptables-save command to make a script you can run with iptables-restore to restore your firewall settings. Such a script is often called at bootup. Many distributions have an iptables initialization script that uses the output from iptables-save

Opcje wykonania iptables w konsoli

-h [icmp] , --help [icmp]

Print help message. If icmp is specified, a list of valid ICMP type names will be printed. -h can also be used with the -m option to get help on an extension module.

--line-numbers

Used with the -L command. Add the line number to the beginning of each rule in a listing, indicating its position in the chain.

-m module, --match module

Explicitly load matching rule extensions associated with module. See the next section.

--modprobe=command

Use specified command to load any necessary kernel modules while adding or inserting rules into a chain.

-n, --numeric

Print all IP address and port numbers in numeric form. By default, text names are displayed when possible.

-t name, --table name

Apply rules to the specified table. Rules apply to the filter table by default.

-v, --verbose

Verbose mode.

-x, --exact

Expand all numbers in a listing (-L). Display the exact value of the packet and byte counters instead of rounded figures.

Przykłady iptables działanie w Słownik polecenie I

Przykład IPTABLES użycie :
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Przykład IPTABLES użycie :
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Przykład IPTABLES użycie :
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Przykład IPTABLES użycie :
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