linux command

iptables – Linux Command คำสั่งจัดการกรอง ip port ที่เข้ามาใช้งาน

iptables

Linux Command – iptables ใช้ในการจัดการกรอง ip port ที่เข้ามาใช้งาน

 

คำสั่ง

1. แสดงข้อมูลการกรอง conncetion

$ iptables -L INPUT -n --line-numbers

 

2. ลบ iptables rule

$ iptables -D INPUT <line-number>

 

3. เพิ่ม iptables rule

$ iptables -I INPUT 2 -s 202.54.1.2 -j DROP

 

โครงสร้างคำสั่ง

 iptables [-t table] {-A|-C|-D} chain rule-specification
 ip6tables [-t table] {-A|-C|-D} chain rule-specification
 iptables [-t table] -I chain [rulenum] rule-specification
 iptables [-t table] -R chain rulenum rule-specification
 iptables [-t table] -D chain rulenum
 iptables [-t table] -S [chain [rulenum]]
 iptables [-t table] {-F|-L|-Z} [chain [rulenum]] [options...]
 iptables [-t table] -N chain
 iptables [-t table] -X [chain]
 iptables [-t table] -P chain target
 iptables [-t table] -E old-chain-name new-chain-name
 rule-specification = [matches...] [target]
 match = -m matchname [per-match-options]
 target = -j targetname [per-target-options]

 

รายละเอียด

เป็นคำสั่งที่ใช้ในการจัดการกรอง ip port ที่เข้ามาใช้งาน หรือ การทำ packet filtering (IP/Port)

 

Option

 COMMANDS
 These options specify the desired action to perform. Only one of them can be specified on the command line unless otherwise stated below. For long versions of the command and
 option names, you need to use only enough letters to ensure that iptables can differentiate it from all other options.

 -A, --append chain rule-specification
 Append one or more rules to the end of the selected chain. When the source and/or destination names resolve to more than one address, a rule will be added for each possible
 address combination.

 -C, --check chain rule-specification
 Check whether a rule matching the specification does exist in the selected chain. This command uses the same logic as -D to find a matching entry, but does not alter the
 existing iptables configuration and uses its exit code to indicate success or failure.

 -D, --delete chain rule-specification
 -D, --delete chain rulenum
 Delete one or more rules from the selected chain. There are two versions of this command: the rule can be specified as a number in the chain (starting at 1 for the first
 rule) or a rule to match.

 -I, --insert chain [rulenum] rule-specification
 Insert one or more rules in the selected chain as the given rule number. So, if the rule number is 1, the rule or rules are inserted at the head of the chain. This is also
 the default if no rule number is specified.

 -R, --replace chain rulenum rule-specification
 Replace a rule in the selected chain. If the source and/or destination names resolve to multiple addresses, the command will fail. Rules are numbered starting at 1.

 -L, --list [chain]
 List all rules in the selected chain. If no chain is selected, all chains are listed. Like every other iptables command, it applies to the specified table (filter is the
 default), so NAT rules get listed by
 iptables -t nat -n -L
 Please note that it is often used with the -n option, in order to avoid long reverse DNS lookups. It is legal to specify the -Z (zero) option as well, in which case the
 chain(s) will be atomically listed and zeroed. The exact output is affected by the other arguments given. The exact rules are suppressed until you use
 iptables -L -v

 -S, --list-rules [chain]
 Print all rules in the selected chain. If no chain is selected, all chains are printed like iptables-save. Like every other iptables command, it applies to the specified
 table (filter is the default).

 -F, --flush [chain]
 Flush the selected chain (all the chains in the table if none is given). This is equivalent to deleting all the rules one by one.

 -Z, --zero [chain [rulenum]]
 Zero the packet and byte counters in all chains, or only the given chain, or only the given rule in a chain. It is legal to specify the -L, --list (list) option as well, to
 see the counters immediately before they are cleared. (See above.)

 -N, --new-chain chain
 Create a new user-defined chain by the given name. There must be no target of that name already.

 -X, --delete-chain [chain]
 Delete the optional user-defined chain specified. There must be no references to the chain. If there are, you must delete or replace the referring rules before the chain
 can be deleted. The chain must be empty, i.e. not contain any rules. If no argument is given, it will attempt to delete every non-builtin chain in the table.

 -P, --policy chain target
 Set the policy for the built-in (non-user-defined) chain to the given target. The policy target must be either ACCEPT or DROP.

 -E, --rename-chain old-chain new-chain
 Rename the user specified chain to the user supplied name. This is cosmetic, and has no effect on the structure of the table.

 -h Help. Give a (currently very brief) description of the command syntax.

 PARAMETERS
 The following parameters make up a rule specification (as used in the add, delete, insert, replace and append commands).

 -4, --ipv4
 This option has no effect in iptables and iptables-restore. If a rule using the -4 option is inserted with (and only with) ip6tables-restore, it will be silently ignored.
 Any other uses will throw an error. This option allows IPv4 and IPv6 rules in a single rule file for use with both iptables-restore and ip6tables-restore.

 -6, --ipv6
 If a rule using the -6 option is inserted with (and only with) iptables-restore, it will be silently ignored. Any other uses will throw an error. This option allows IPv4 and
 IPv6 rules in a single rule file for use with both iptables-restore and ip6tables-restore. This option has no effect in ip6tables and ip6tables-restore.

 [!] -p, --protocol protocol
 The protocol of the rule or of the packet to check. The specified protocol can be one of tcp, udp, udplite, icmp, icmpv6,esp, ah, sctp, mh or the special keyword "all", or
 it can be a numeric value, representing one of these protocols or a different one. A protocol name from /etc/protocols is also allowed. A "!" argument before the protocol
 inverts the test. The number zero is equivalent to all. "all" will match with all protocols and is taken as default when this option is omitted. Note that, in ip6tables,
 IPv6 extension headers except esp are not allowed. esp and ipv6-nonext can be used with Kernel version 2.6.11 or later. The number zero is equivalent to all, which means
 that you cannot test the protocol field for the value 0 directly. To match on a HBH header, even if it were the last, you cannot use -p 0, but always need -m hbh.

 [!] -s, --source address[/mask][,...]
 Source specification. Address can be either a network name, a hostname, a network IP address (with /mask), or a plain IP address. Hostnames will be resolved once only,
 before the rule is submitted to the kernel. Please note that specifying any name to be resolved with a remote query such as DNS is a really bad idea. The mask can be
 either an ipv4 network mask (for iptables) or a plain number, specifying the number of 1's at the left side of the network mask. Thus, an iptables mask of 24 is equivalent
 to 255.255.255.0. A "!" argument before the address specification inverts the sense of the address. The flag --src is an alias for this option. Multiple addresses can be
 specified, but this will expand to multiple rules (when adding with -A), or will cause multiple rules to be deleted (with -D).

 [!] -d, --destination address[/mask][,...]
 Destination specification. See the description of the -s (source) flag for a detailed description of the syntax. The flag --dst is an alias for this option.

 -m, --match match
 Specifies a match to use, that is, an extension module that tests for a specific property. The set of matches make up the condition under which a target is invoked. Matches
 are evaluated first to last as specified on the command line and work in short-circuit fashion, i.e. if one extension yields false, evaluation will stop.

 -j, --jump target
 This specifies the target of the rule; i.e., what to do if the packet matches it. The target can be a user-defined chain (other than the one this rule is in), one of the
 special builtin targets which decide the fate of the packet immediately, or an extension (see EXTENSIONS below). If this option is omitted in a rule (and -g is not used),
 then matching the rule will have no effect on the packet's fate, but the counters on the rule will be incremented.

 -g, --goto chain
 This specifies that the processing should continue in a user specified chain. Unlike the --jump option return will not continue processing in this chain but instead in the
 chain that called us via --jump.

 [!] -i, --in-interface name
 Name of an interface via which a packet was received (only for packets entering the INPUT, FORWARD and PREROUTING chains). When the "!" argument is used before the inter‐
 face name, the sense is inverted. If the interface name ends in a "+", then any interface which begins with this name will match. If this option is omitted, any interface
 name will match.

 [!] -o, --out-interface name
 Name of an interface via which a packet is going to be sent (for packets entering the FORWARD, OUTPUT and POSTROUTING chains). When the "!" argument is used before the
 interface name, the sense is inverted. If the interface name ends in a "+", then any interface which begins with this name will match. If this option is omitted, any
 interface name will match.

 [!] -f, --fragment
 This means that the rule only refers to second and further IPv4 fragments of fragmented packets. Since there is no way to tell the source or destination ports of such a
 packet (or ICMP type), such a packet will not match any rules which specify them. When the "!" argument precedes the "-f" flag, the rule will only match head fragments, or
 unfragmented packets. This option is IPv4 specific, it is not available in ip6tables.

 -c, --set-counters packets bytes
 This enables the administrator to initialize the packet and byte counters of a rule (during INSERT, APPEND, REPLACE operations).

 OTHER OPTIONS
 The following additional options can be specified:

 -v, --verbose
 Verbose output. This option makes the list command show the interface name, the rule options (if any), and the TOS masks. The packet and byte counters are also listed,
 with the suffix 'K', 'M' or 'G' for 1000, 1,000,000 and 1,000,000,000 multipliers respectively (but see the -x flag to change this). For appending, insertion, deletion and
 replacement, this causes detailed information on the rule or rules to be printed. -v may be specified multiple times to possibly emit more detailed debug statements.

 -w, --wait [seconds]
 Wait for the xtables lock. To prevent multiple instances of the program from running concurrently, an attempt will be made to obtain an exclusive lock at launch. By
 default, the program will exit if the lock cannot be obtained. This option will make the program wait (indefinitely or for optional seconds) until the exclusive lock can be
 obtained.

 -n, --numeric
 Numeric output. IP addresses and port numbers will be printed in numeric format. By default, the program will try to display them as host names, network names, or services
 (whenever applicable).

 -x, --exact
 Expand numbers. Display the exact value of the packet and byte counters, instead of only the rounded number in K's (multiples of 1000) M's (multiples of 1000K) or G's (mul‐
 tiples of 1000M). This option is only relevant for the -L command.

 --line-numbers
 When listing rules, add line numbers to the beginning of each rule, corresponding to that rule's position in the chain.

 --modprobe=command
 When adding or inserting rules into a chain, use command to load any necessary modules (targets, match extensions, etc).

 

กลุ่มคำสั่ง

ping, ifconfig, netstat, traceroute, iptables-apply(8), iptables-save(8), iptables-restore(8), iptables-extensions(8),

 

Reference:

คำสั่ง Unix – Linux Command

Linux, Unix

 

Author: Suphakit Annoppornchai

Credit: https://saixiii.com

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