iptables - Modify the systems iptables
New in version 2.0.
Synopsis
Iptables is used to set up, maintain, and inspect the tables of IP packet filter rules in the Linux kernel. This module does not handle the saving and/or loading of rules, but rather only manipulates the current rules that are present in memory. This is the same as the behaviour of the “iptables” and “ip6tables” command which this module uses internally.
Options
| parameter | required | default | choices | comments |
|---|---|---|---|---|
| chain |
yes | Chain to operate on. This option can either be the name of a user defined chain or any of the builtin chains: 'INPUT', 'FORWARD', 'OUTPUT', 'PREROUTING', 'POSTROUTING', 'SECMARK', 'CONNSECMARK' | ||
| comment |
no | This specifies a comment that will be added to the rule | ||
| ctstate |
no | ctstate is a list of the connection states to match in the conntrack module. Possible states are: 'INVALID', 'NEW', 'ESTABLISHED', 'RELATED', 'UNTRACKED', 'SNAT', 'DNAT' | ||
| destination |
no | Destination 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 a network mask or a plain number, specifying the number of 1's at the left side of the network mask. Thus, a mask of 24 is equivalent to 255.255.255.0. A "!" argument before the address specification inverts the sense of the address.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 a network mask or a plain number, specifying the number of 1's at the left side of the network mask. Thus, a mask of 24 is equivalent to 255.255.255.0. A "!" argument before the address specification inverts the sense of the address. | ||
| destination_port |
no | Destination port or port range specification. This can either be a service name or a port number. An inclusive range can also be specified, using the format first:last. If the first port is omitted, '0' is assumed; if the last is omitted, '65535' is assumed. If the first port is greater than the second one they will be swapped. | ||
| fragment |
no | This means that the rule only refers to second and further 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 fragment argument, the rule will only match head fragments, or unfragmented packets. | ||
| goto |
no | This specifies that the processing should continue in a user specified chain. Unlike the jump argument return will not continue processing in this chain but instead in the chain that called us via jump. | ||
| in_interface |
no | 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 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. | ||
| ip_version |
no | ipv4 |
|
Which version of the IP protocol this rule should apply to. |
| jump |
no | 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 the goto paramater 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. | ||
| limit |
no | Specifies the maximum average number of matches to allow per second. The number can specify units explicitly, using `/second', `/minute', `/hour' or `/day', or parts of them (so `5/second' is the same as `5/s'). | ||
| limit_burst (added in 2.1) |
no | Specifies the maximum burst before the above limit kicks in. | ||
| match |
no | 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 if specified as an array and work in short-circuit fashion, i.e. if one extension yields false, evaluation will stop. | ||
| out_interface |
no | 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. | ||
| protocol |
no | The protocol of the rule or of the packet to check. The specified protocol can be one of tcp, udp, udplite, icmp, esp, ah, sctp 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. | ||
| reject_with (added in 2.1) |
no | Specifies the error packet type to return while rejecting. | ||
| set_counters |
no | This enables the administrator to initialize the packet and byte counters of a rule (during INSERT, APPEND, REPLACE operations). | ||
| set_dscp_mark (added in 2.1) |
no | This allows specifying a DSCP mark to be added to packets. It takes either an integer or hex value. Mutually exclusive with set_dscp_mark_class. | ||
| set_dscp_mark_class (added in 2.1) |
no | This allows specifying a predefined DiffServ class which will be translated to the corresponding DSCP mark. Mutually exclusive with set_dscp_mark. | ||
| source |
no | 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 a network mask or a plain number, specifying the number of 1's at the left side of the network mask. Thus, a mask of 24 is equivalent to 255.255.255.0. A "!" argument before the address specification inverts the sense of the address.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 a network mask or a plain number, specifying the number of 1's at the left side of the network mask. Thus, a mask of 24 is equivalent to 255.255.255.0. A "!" argument before the address specification inverts the sense of the address. | ||
| source_port |
no | Source port or port range specification. This can either be a service name or a port number. An inclusive range can also be specified, using the format first:last. If the first port is omitted, '0' is assumed; if the last is omitted, '65535' is assumed. If the first port is greater than the second one they will be swapped. | ||
| state |
no | present |
|
Whether the rule should be absent or present. |
| table |
no | filter |
|
This option specifies the packet matching table which the command should operate on. If the kernel is configured with automatic module loading, an attempt will be made to load the appropriate module for that table if it is not already there. |
| to_destination (added in 2.1) |
no | This specifies a destination address to use with DNAT: without this, the destination address is never altered. | ||
| to_ports |
no | This specifies a destination port or range of ports to use: without this, the destination port is never altered. This is only valid if the rule also specifies one of the following protocols: tcp, udp, dccp or sctp. | ||
| uid_owner (added in 2.1) |
no | Specifies the UID or username to use in match by owner rule. |
Examples
# Block specific IP - iptables: chain=INPUT source=8.8.8.8 jump=DROP become: yes # Forward port 80 to 8600 - iptables: table=nat chain=PREROUTING in_interface=eth0 protocol=tcp match=tcp destination_port=80 jump=REDIRECT to_ports=8600 comment="Redirect web traffic to port 8600" become: yes # Allow related and established connections - iptables: chain=INPUT ctstate=ESTABLISHED,RELATED jump=ACCEPT become: yes # Tag all outbound tcp packets with DSCP mark 8 - iptables: chain=OUTPUT jump=DSCP table=mangle set_dscp_mark=8 protocol=tcp # Tag all outbound tcp packets with DSCP DiffServ class CS1 - iptables: chain=OUTPUT jump=DSCP table=mangle set_dscp_mark_class=CS1 protocol=tcp
Notes
Note
This module just deals with individual rules. If you need advanced chaining of rules the recommended way is to template the iptables restore file.
This is an Extras Module
For more information on what this means please read Extras Modules
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