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diff --git a/iptables.8.in b/iptables.8.in new file mode 100644 index 0000000..d29deb2 --- /dev/null +++ b/iptables.8.in @@ -0,0 +1,429 @@ +.TH IPTABLES 8 "" "@PACKAGE_AND_VERSION@" "@PACKAGE_AND_VERSION@" +.\" +.\" Man page written by Herve Eychenne <rv@wallfire.org> (May 1999) +.\" It is based on ipchains page. +.\" TODO: add a word for protocol helpers (FTP, IRC, SNMP-ALG) +.\" +.\" ipchains page by Paul ``Rusty'' Russell March 1997 +.\" Based on the original ipfwadm man page by Jos Vos <jos@xos.nl> +.\" +.\" This program is free software; you can redistribute it and/or modify +.\" it under the terms of the GNU General Public License as published by +.\" the Free Software Foundation; either version 2 of the License, or +.\" (at your option) any later version. +.\" +.\" This program is distributed in the hope that it will be useful, +.\" but WITHOUT ANY WARRANTY; without even the implied warranty of +.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +.\" GNU General Public License for more details. +.\" +.\" You should have received a copy of the GNU General Public License +.\" along with this program; if not, write to the Free Software +.\" Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +.\" +.\" +.SH NAME +iptables \(em administration tool for IPv4 packet filtering and NAT +.SH SYNOPSIS +\fBiptables\fP [\fB\-t\fP \fItable\fP] {\fB\-A\fP|\fB\-D\fP} \fIchain\fP \fIrule-specification\fP +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-I\fP \fIchain\fP [\fIrulenum\fP] \fIrule-specification\fP +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-R\fP \fIchain rulenum rule-specification\fP +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-D\fP \fIchain rulenum\fP +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-S\fP [\fIchain\fP [\fIrulenum\fP]] +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] {\fB\-F\fP|\fB\-L\fP|\fB\-Z\fP} [\fIchain\fP [\fIrulenum\fP]] [\fIoptions...\fP] +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-N\fP \fIchain\fP +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-X\fP [\fIchain\fP] +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-P\fP \fIchain target\fP +.PP +\fBiptables\fP [\fB\-t\fP \fItable\fP] \fB\-E\fP \fIold-chain-name new-chain-name\fP +.PP +rule-specification = [\fImatches...\fP] [\fItarget\fP] +.PP +match = \fB\-m\fP \fImatchname\fP [\fIper-match-options\fP] +.PP +target = \fB\-j\fP \fItargetname\fP [\fIper\-target\-options\fP] +.SH DESCRIPTION +\fBIptables\fP is used to set up, maintain, and inspect the +tables of IPv4 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. +.PP +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. +.SH 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 \fBACCEPT\fP, \fBDROP\fP, \fBQUEUE\fP or \fBRETURN\fP. +.PP +\fBACCEPT\fP means to let the packet through. +\fBDROP\fP means to drop the packet on the floor. +\fBQUEUE\fP 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 \fBip_queue\fP +queue handler. Kernels 2.6.14 and later additionally include the +\fBnfnetlink_queue\fP queue handler. Packets with a target of QUEUE will be +sent to queue number '0' in this case. Please also see the \fBNFQUEUE\fP +target as described later in this man page.) +\fBRETURN\fP 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 \fBRETURN\fP +is matched, the target specified by the chain policy determines the +fate of the packet. +.SH TABLES +There are currently three independent tables (which tables are present +at any time depends on the kernel configuration options and which +modules are present). +.TP +\fB\-t\fP, \fB\-\-table\fP \fItable\fP +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: +.RS +.TP .4i +\fBfilter\fP: +This is the default table (if no \-t option is passed). It contains +the built-in chains \fBINPUT\fP (for packets destined to local sockets), +\fBFORWARD\fP (for packets being routed through the box), and +\fBOUTPUT\fP (for locally-generated packets). +.TP +\fBnat\fP: +This table is consulted when a packet that creates a new +connection is encountered. It consists of three built-ins: \fBPREROUTING\fP +(for altering packets as soon as they come in), \fBOUTPUT\fP +(for altering locally-generated packets before routing), and \fBPOSTROUTING\fP +(for altering packets as they are about to go out). +.TP +\fBmangle\fP: +This table is used for specialized packet alteration. Until kernel +2.4.17 it had two built-in chains: \fBPREROUTING\fP +(for altering incoming packets before routing) and \fBOUTPUT\fP +(for altering locally-generated packets before routing). +Since kernel 2.4.18, three other built-in chains are also supported: +\fBINPUT\fP (for packets coming into the box itself), \fBFORWARD\fP +(for altering packets being routed through the box), and \fBPOSTROUTING\fP +(for altering packets as they are about to go out). +.TP +\fBraw\fP: +This table is used mainly for configuring exemptions from connection +tracking in combination with the NOTRACK target. It registers at the netfilter +hooks with higher priority and is thus called before ip_conntrack, or any other +IP tables. It provides the following built-in chains: \fBPREROUTING\fP +(for packets arriving via any network interface) \fBOUTPUT\fP +(for packets generated by local processes) +.RE +.SH OPTIONS +The options that are recognized by +\fBiptables\fP can be divided into several different groups. +.SS 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 +\fBiptables\fP can differentiate it from all other options. +.TP +\fB\-A\fP, \fB\-\-append\fP \fIchain rule-specification\fP +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. +.TP +\fB\-D\fP, \fB\-\-delete\fP \fIchain rule-specification\fP +.ns +.TP +\fB\-D\fP, \fB\-\-delete\fP \fIchain rulenum\fP +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. +.TP +\fB\-I\fP, \fB\-\-insert\fP \fIchain\fP [\fIrulenum\fP] \fIrule-specification\fP +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. +.TP +\fB\-R\fP, \fB\-\-replace\fP \fIchain rulenum rule-specification\fP +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. +.TP +\fB\-L\fP, \fB\-\-list\fP [\fIchain\fP] +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 +.nf + iptables \-t nat \-n \-L +.fi +Please note that it is often used with the \fB\-n\fP +option, in order to avoid long reverse DNS lookups. +It is legal to specify the \fB\-Z\fP +(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 +.nf + iptables \-L \-v +.fi +.TP +\fB\-S\fP, \fB\-\-list\-rules\fP [\fIchain\fP] +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). +.TP +\fB\-F\fP, \fB\-\-flush\fP [\fIchain\fP] +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. +.TP +\fB\-Z\fP, \fB\-\-zero\fP [\fIchain\fP [\fIrulenum\fP]] +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 +\fB\-L\fP, \fB\-\-list\fP +(list) option as well, to see the counters immediately before they are +cleared. (See above.) +.TP +\fB\-N\fP, \fB\-\-new\-chain\fP \fIchain\fP +Create a new user-defined chain by the given name. There must be no +target of that name already. +.TP +\fB\-X\fP, \fB\-\-delete\-chain\fP [\fIchain\fP] +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. +.TP +\fB\-P\fP, \fB\-\-policy\fP \fIchain target\fP +Set the policy for the chain to the given target. See the section \fBTARGETS\fP +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. +.TP +\fB\-E\fP, \fB\-\-rename\-chain\fP \fIold\-chain new\-chain\fP +Rename the user specified chain to the user supplied name. This is +cosmetic, and has no effect on the structure of the table. +.TP +\fB\-h\fP +Help. +Give a (currently very brief) description of the command syntax. +.SS PARAMETERS +The following parameters make up a rule specification (as used in the +add, delete, insert, replace and append commands). +.TP +[\fB!\fP] \fB\-p\fP, \fB\-\-protocol\fP \fIprotocol\fP +The protocol of the rule or of the packet to check. +The specified protocol can be one of \fBtcp\fP, \fBudp\fP, \fBudplite\fP, +\fBicmp\fP, \fBesp\fP, \fBah\fP, \fBsctp\fP or \fBall\fP, +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 \fBall\fP. +Protocol \fBall\fP +will match with all protocols and is taken as default when this +option is omitted. +.TP +[\fB!\fP] \fB\-s\fP, \fB\-\-source\fP \fIaddress\fP[\fB/\fP\fImask\fP][\fB,\fP\fI...\fP] +Source specification. \fIAddress\fP +can be either a network name, a hostname, a network IP address (with +\fB/\fP\fImask\fP), 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 \fImask\fP +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 \fI24\fP is equivalent to \fI255.255.255.0\fP. +A "!" argument before the address specification inverts the sense of +the address. The flag \fB\-\-src\fP is an alias for this option. +Multiple addresses can be specified, but this will \fBexpand to multiple +rules\fP (when adding with \-A), or will cause multiple rules to be +deleted (with \-D). +.TP +[\fB!\fP] \fB\-d\fP, \fB\-\-destination\fP \fIaddress\fP[\fB/\fP\fImask\fP][\fB,\fP\fI...\fP] +Destination specification. +See the description of the \fB\-s\fP +(source) flag for a detailed description of the syntax. The flag +\fB\-\-dst\fP is an alias for this option. +.TP +\fB\-j\fP, \fB\-\-jump\fP \fItarget\fP +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 \fBEXTENSIONS\fP +below). If this +option is omitted in a rule (and \fB\-g\fP +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. +.TP +\fB\-g\fP, \fB\-\-goto\fP \fIchain\fP +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. +.TP +[\fB!\fP] \fB\-i\fP, \fB\-\-in\-interface\fP \fIname\fP +Name of an interface via which a packet was received (only for +packets entering the \fBINPUT\fP, \fBFORWARD\fP and \fBPREROUTING\fP +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. +.TP +[\fB!\fP] \fB\-o\fP, \fB\-\-out\-interface\fP \fIname\fP +Name of an interface via which a packet is going to be sent (for packets +entering the \fBFORWARD\fP, \fBOUTPUT\fP and \fBPOSTROUTING\fP +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. +.TP +[\fB!\fP] \fB\-f\fP, \fB\-\-fragment\fP +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 the "\-f" flag, the rule will only match head fragments, or +unfragmented packets. +.TP +\fB\-c\fP, \fB\-\-set\-counters\fP \fIpackets bytes\fP +This enables the administrator to initialize the packet and byte +counters of a rule (during \fBINSERT\fP, \fBAPPEND\fP, \fBREPLACE\fP +operations). +.SS "OTHER OPTIONS" +The following additional options can be specified: +.TP +\fB\-v\fP, \fB\-\-verbose\fP +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 \fB\-x\fP flag to change this). +For appending, insertion, deletion and replacement, this causes +detailed information on the rule or rules to be printed. +.TP +\fB\-n\fP, \fB\-\-numeric\fP +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). +.TP +\fB\-x\fP, \fB\-\-exact\fP +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 \fB\-L\fP command. +.TP +\fB\-\-line\-numbers\fP +When listing rules, add line numbers to the beginning of each rule, +corresponding to that rule's position in the chain. +.TP +\fB\-\-modprobe=\fP\fIcommand\fP +When adding or inserting rules into a chain, use \fIcommand\fP +to load any necessary modules (targets, match extensions, etc). +.SH MATCH EXTENSIONS +iptables can use extended packet matching modules. These are loaded +in two ways: implicitly, when \fB\-p\fP or \fB\-\-protocol\fP +is specified, or with the \fB\-m\fP or \fB\-\-match\fP +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 \fB\-h\fP or \fB\-\-help\fP +options after the module has been specified to receive help specific +to that module. +.PP +The following are included in the base package, and most of these can +be preceded by a "\fB!\fP" to invert the sense of the match. +.\" @MATCH@ +.SH TARGET EXTENSIONS +iptables can use extended target modules: the following are included +in the standard distribution. +.\" @TARGET@ +.SH 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. +.SH BUGS +Bugs? What's this? ;-) +Well, you might want to have a look at http://bugzilla.netfilter.org/ +.SH COMPATIBILITY WITH IPCHAINS +This \fBiptables\fP +is very similar to ipchains by Rusty Russell. The main difference is +that the chains \fBINPUT\fP and \fBOUTPUT\fP +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. +.PP +The other main difference is that \fB\-i\fP refers to the input interface; +\fB\-o\fP refers to the output interface, and both are available for packets +entering the \fBFORWARD\fP chain. +.PP +The various forms of NAT have been separated out; \fBiptables\fP +is a pure packet filter when using the default `filter' table, with +optional extension modules. This should simplify much of the previous +confusion over the combination of IP masquerading and packet filtering +seen previously. So the following options are handled differently: +.nf + \-j MASQ + \-M \-S + \-M \-L +.fi +There are several other changes in iptables. +.SH SEE ALSO +\fBiptables\-save\fP(8), +\fBiptables\-restore\fP(8), +\fBip6tables\fP(8), +\fBip6tables\-save\fP(8), +\fBip6tables\-restore\fP(8), +\fBlibipq\fP(3). +.PP +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. +.br +See +.BR "http://www.netfilter.org/" . +.SH AUTHORS +Rusty Russell originally wrote iptables, in early consultation with Michael +Neuling. +.PP +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. +.PP +James Morris wrote the TOS target, and tos match. +.PP +Jozsef Kadlecsik wrote the REJECT target. +.PP +Harald Welte wrote the ULOG and NFQUEUE target, the new libiptc, as well as the TTL, DSCP, ECN matches and targets. +.PP +The Netfilter Core Team is: Marc Boucher, Martin Josefsson, Yasuyuki Kozakai, +Jozsef Kadlecsik, Patrick McHardy, James Morris, Pablo Neira Ayuso, +Harald Welte and Rusty Russell. +.PP +Man page originally written by Herve Eychenne <rv@wallfire.org>. +.\" .. and did I mention that we are incredibly cool people? +.\" .. sexy, too .. +.\" .. witty, charming, powerful .. +.\" .. and most of all, modest .. |