IP6TABLES(8)

NAME
ip6tables - IPv6 packet filter administration

SYNOPSIS
ip6tables [-t table] -[AD] chain rule-specification [options]
ip6tables [-t table] -I chain [rulenum] rule-specification [options]
ip6tables [-t table] -R chain rulenum rule-specification [options]
ip6tables [-t table] -D chain rulenum [options]
ip6tables [-t table] -[LFZ] [chain] [options]
ip6tables [-t table] -N chain
ip6tables [-t table] -X [chain]
ip6tables [-t table] -P chain target [options]
ip6tables [-t table] -E old-chain-name new-chain-name

DESCRIPTION
Ip6tables is used to set up, maintain, and inspect the tables of IPv6 packet filter rules in the Linux kernel. Several different tables may be defined. Each table contains a number of built-in chains and may also contain user-defined chains. Each chain is a list of rules which can match a set of packets. Each rule specifies what to do with a packet that matches. This is called a `target', which may be a jump to a user-defined chain in the same table.

TARGETS
A firewall rule specifies criteria for a packet, and a target. If the packet does not match, the next rule in the chain is the examined; if it does match, then the next rule is specified by the value of the target, which can be the name of a user-defined chain or one of the special values ACCEPT, DROP, QUEUE, or RETURN.

ACCEPT means to let the packet through. DROP means to drop the packet on the floor. QUEUE means to pass the packet to userspace. (How the packet can be received by a userspace process differs by the particular queue handler. 2.4.x and 2.6.x kernels up to 2.6.13 include the ip_queue queue handler. Kernels 2.6.14 and later additionally include the nfnetlink_queue queue handler. Packets with a target of QUEUE will be sent to queue number '0' in this case. Please also see the NFQUEUE target as described later in this man page.) RETURN means stop traversing this chain and resume at the next rule in the previous (calling) chain. If the end of a built-in chain is reached or a rule in a built-in chain with target RETURN is matched, the target specified by the chain policy determines the fate of the packet.

TABLES
There are currently two independent tables (which tables are present at any time depends on the kernel configuration options and which modules are present), as nat table has not been implemented yet.

-t, --table table
    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. The tables are as follows:

    filter:
        This is the default table (if no -t option is passed). It contains the built-in chains INPUT (for packets coming into the box itself), FORWARD (for packets being routed through the box), and OUTPUT (for locally-generated packets).

    mangle:
        This table is used for specialized packet alteration. Until kernel 2.4.17 it had two built-in chains: PREROUTING (for altering incoming packets before routing) and OUTPUT (for altering locally-generated packets before routing). Since kernel 2.4.18, three other built-in chains are also supported: INPUT (for packets coming into the box itself), FORWARD (for altering packets being routed through the box), and POSTROUTING (for altering packets as they are about to go out).

OPTIONS
The options that are recognized by ip6tables can be divided into several different groups.

  COMMANDS
These options specify the specific action to perform. Only one of them can be specified on the command line unless otherwise specified below. For all the long versions of the command and option names, you need to use only enough letters to ensure that ip6tables 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.

-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
    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. As every other iptables command, it applies to the specified table (filter is the default), so mangle rules get listed by
     ip6tables -t mangle -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
     ip6tables -L -v

-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]
    Zero the packet and byte counters in all chains. 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. 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 chain to the given target. See the section TARGETS for the legal targets. Only built-in (non-user-defined) chains can have policies, and neither built-in nor user-defined chains can be policy targets.

-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).

-p, --protocol [!] protocol
    The protocol of the rule or of the packet to check. The specified protocol can be one of tcp, udp, ipv6-icmp|icmpv6, or 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. Protocol all will match with all protocols and is taken as default when this option is omitted.

-s, --source [!] address[/mask]
    Source specification. Address can be either a hostname (please note that specifying any name to be resolved with a remote query such as DNS is a really bad idea), a network IPv6 address (with /mask), or a plain IPv6 address. (the network name isn't supported now). 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 64 is equivalent to ffff:ffff:ffff:ffff:0000:0000:0000:0000. A "!" argument before the address specification inverts the sense of the address. The flag --src is an alias for this option.

-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.

-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, then matching the rule will have no effect on the packet's fate, but the counters on the rule will be incremented.

-i, --in-interface [!] name
    Name of an interface via which a packet is going to be 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.

-o, --out-interface [!] name
    Name of an interface via which a packet is going to be sent (for packets entering the FORWARD and OUTPUT 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.

-c, --set-counters  PKTS 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.

-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 (multiples 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).

MATCH EXTENSIONS
ip6tables can use extended packet matching modules. These are loaded in two ways: implicitly, when -p or --protocol is specified, or with the -m or --match options, followed by the matching module name; after these, various extra command line options become available, depending on the specific module. You can specify multiple extended match modules in one line, and you can use the -h or --help options after the module has been specified to receive help specific to that module. The following are included in the base package, and most of these can be preceded by a ! to invert the sense of the match.

TARGET EXTENSIONS
ip6tables can use extended target modules: the following are included in the standard distribution.

DIAGNOSTICS
Various error messages are printed to standard error. The exit code is 0 for correct functioning. Errors which appear to be caused by invalid or abused command line parameters cause an exit code of 2, and other errors cause an exit code of 1.

BUGS
Bugs? What's this? ;-) Well... the counters are not reliable on sparc64.

COMPATIBILITY WITH IPCHAINS
This ip6tables is very similar to ipchains by Rusty Russell. The main difference is that the chains INPUT and OUTPUT are only traversed for packets coming into the local host and originating from the local host respectively. Hence every packet only passes through one of the three chains (except loopback traffic, which involves both INPUT and OUTPUT chains); previously a forwarded packet would pass through all three.

The other main difference is that -i refers to the input interface; -o refers to the output interface, and both are available for packets entering the FORWARD chain. There are several other changes in ip6tables.

SEE ALSO
ip6tables-save(8), ip6tables-restore(8), iptables(8), iptables-save(8), iptables-restore(8), libipq(3).

The packet-filtering-HOWTO details iptables usage for packet filtering, the NAT-HOWTO details NAT, the netfilter-extensions-HOWTO details the extensions that are not in the standard distribution, and the netfilter-hacking-HOWTO details the netfilter internals.
See http://www.netfilter.org/.

AUTHORS
Rusty Russell wrote iptables, in early consultation with Michael Neuling.

Marc Boucher made Rusty abandon ipnatctl by lobbying for a generic packet selection framework in iptables, then wrote the mangle table, the owner match, the mark stuff, and ran around doing cool stuff everywhere.

James Morris wrote the TOS target, and tos match.

Jozsef Kadlecsik wrote the REJECT target.

Harald Welte wrote the ULOG and NFQUEUE target, the new libiptc, aswell as TTL match+target and libipulog.

The Netfilter Core Team is: Marc Boucher, Martin Josefsson, Jozsef Kadlecsik, James Morris, Harald Welte and Rusty Russell.

ip6tables man page created by Andras Kis-Szabo, based on iptables man page written by Herve Eychenne <rv@wallfire.org>.