.TH EBTABLES 8  "December 2011"

.\"

.\" Man page written by Bart De Schuymer <bdschuym@pandora.be>

.\" It is based on the iptables man page.

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.SH NAME

ebtables \- Ethernet bridge frame table administration (nft-based)

.SH SYNOPSIS

.BR "ebtables " [ -t " table ] " - [ ACDI "] chain rule specification [match extensions] [watcher extensions] target"

.br

.BR "ebtables " [ -t " table ] " -P " chain " ACCEPT " | " DROP " | " RETURN

.br

.BR "ebtables " [ -t " table ] " -F " [chain]"

.br

.BR "ebtables " [ -t " table ] " -Z " [chain]"

.br

.BR "ebtables " [ -t " table ] " -L " [" -Z "] [chain] [ [" --Ln "] | [" --Lx "] ] [" --Lc "] [" --Lmac2 ]

.br

.BR "ebtables " [ -t " table ] " -N " chain [" "-P ACCEPT " | " DROP " | " RETURN" ]

.br

.BR "ebtables " [ -t " table ] " -X " [chain]"

.br

.BR "ebtables " [ -t " table ] " -E " old-chain-name new-chain-name"

.br

.BR "ebtables " [ -t " table ] " --init-table

.br

.BR "ebtables " [ -t " table ] [" --atomic-file " file] " --atomic-commit

.br

.BR "ebtables " [ -t " table ] [" --atomic-file " file] " --atomic-init

.br

.BR "ebtables " [ -t " table ] [" --atomic-file " file] " --atomic-save

.br

.SH DESCRIPTION

.B ebtables

is an application program used to set up and maintain the

tables of rules (inside the Linux kernel) that inspect

Ethernet frames.

It is analogous to the

.B iptables

application, but less complicated, due to the fact that the Ethernet protocol

is much simpler than the IP protocol.

.SS CHAINS

There are two ebtables tables with built-in chains in the

Linux kernel. These tables are used to divide functionality into

different sets of rules. Each set of rules is called a chain.

Each chain is an ordered list of rules that can match Ethernet frames. If a

rule matches an Ethernet frame, then a processing specification tells

what to do with that matching frame. The processing specification is

called a 'target'. However, if the frame does not match the current

rule in the chain, then the next rule in the chain is examined and so forth.

The user can create new (user-defined) chains that can be used as the 'target'

of a rule. User-defined chains are very useful to get better performance

over the linear traversal of the rules and are also essential for structuring

the filtering rules into well-organized and maintainable sets of rules.

.SS TARGETS

A firewall rule specifies criteria for an Ethernet frame and a frame

processing specification called a target.  When a frame matches a rule,

then the next action performed by the kernel is specified by the target.

The target can be one of these values:

.BR ACCEPT ,

.BR DROP ,

.BR CONTINUE ,

.BR RETURN ,

an 'extension' (see below) or a jump to a user-defined chain.

.PP

.B ACCEPT

means to let the frame through.

.B DROP

means the frame has to be dropped.

.B CONTINUE

means the next rule has to be checked. This can be handy, f.e., to know how many

frames pass a certain point in the chain, to log those frames or to apply multiple

targets on a frame.

.B RETURN

means stop traversing this chain and resume at the next rule in the

previous (calling) chain.

For the extension targets please refer to the

.B "TARGET EXTENSIONS"

section of this man page.

.SS TABLES

As stated earlier, there are two ebtables tables in the Linux

kernel.  The table names are

.BR filter " and " nat .

Of these two tables,

the filter table is the default table that the command operates on.

If you are working with the filter table, then you can drop the '-t filter'

argument to the ebtables command.  However, you will need to provide

the -t argument for

.B nat

table.  Moreover, the -t argument must be the

first argument on the ebtables command line, if used. 

.TP

.B "-t, --table"

.br

.B filter

is the default table and contains three built-in chains:

.B INPUT 

(for frames destined for the bridge itself, on the level of the MAC destination address), 

.B OUTPUT 

(for locally-generated or (b)routed frames) and

.B FORWARD 

(for frames being forwarded by the bridge).

.br

.br

.B nat

is mostly used to change the mac addresses and contains three built-in chains:

.B PREROUTING 

(for altering frames as soon as they come in), 

.B OUTPUT 

(for altering locally generated or (b)routed frames before they are bridged) and 

.B POSTROUTING

(for altering frames as they are about to go out). A small note on the naming

of chains PREROUTING and POSTROUTING: it would be more accurate to call them

PREFORWARDING and POSTFORWARDING, but for all those who come from the

iptables world to ebtables it is easier to have the same names. Note that you

can change the name

.BR "" ( -E )

if you don't like the default.

.SH EBTABLES COMMAND LINE ARGUMENTS

After the initial ebtables '-t table' command line argument, the remaining

arguments can be divided into several groups.  These groups

are commands, miscellaneous commands, rule specifications, match extensions,

watcher extensions and target extensions.

.SS COMMANDS

The ebtables command arguments specify the actions to perform on the table

defined with the -t argument.  If you do not use the -t argument to name

a table, the commands apply to the default filter table.

Only one command may be used on the command line at a time, except when

the commands

.BR -L " and " -Z

are combined, the commands

.BR -N " and " -P

are combined, or when

.B --atomic-file

is used.

.TP

.B "-A, --append"

Append a rule to the end of the selected chain.

.TP

.B "-D, --delete"

Delete the specified rule or rules from the selected chain. There are two ways to

use this command. The first is by specifying an interval of rule numbers

to delete (directly after

.BR -D ).

Syntax: \fIstart_nr\fP[\fI:end_nr\fP] (use

.B -L --Ln

to list the rules with their rule number). When \fIend_nr\fP is omitted, all rules starting

from \fIstart_nr\fP are deleted. Using negative numbers is allowed, for more

details about using negative numbers, see the

.B -I

command. The second usage is by

specifying the complete rule as it would have been specified when it was added. Only

the first encountered rule that is the same as this specified rule, in other

words the matching rule with the lowest (positive) rule number, is deleted.

.TP

.B "-C, --change-counters"

Change the counters of the specified rule or rules from the selected chain. There are two ways to

use this command. The first is by specifying an interval of rule numbers

to do the changes on (directly after

.BR -C ).

Syntax: \fIstart_nr\fP[\fI:end_nr\fP] (use

.B -L --Ln

to list the rules with their rule number). The details are the same as for the

.BR -D " command. The second usage is by"

specifying the complete rule as it would have been specified when it was added. Only

the counters of the first encountered rule that is the same as this specified rule, in other

words the matching rule with the lowest (positive) rule number, are changed.

In the first usage, the counters are specified directly after the interval specification,

in the second usage directly after

.BR -C .

First the packet counter is specified, then the byte counter. If the specified counters start

with a '+', the counter values are added to the respective current counter values.

If the specified counters start with a '-', the counter values are decreased from the respective

current counter values. No bounds checking is done. If the counters don't start with '+' or '-',

the current counters are changed to the specified counters.

.TP

.B "-I, --insert"

Insert the specified rule into the selected chain at the specified rule number. If the

rule number is not specified, the rule is added at the head of the chain.

If the current number of rules equals

.IR N ,

then the specified number can be

between

.IR -N " and " N+1 .

For a positive number

.IR i ,

it holds that

.IR i " and " i-N-1

specify the same place in the chain where the rule should be inserted. The rule number

0 specifies the place past the last rule in the chain and using this number is therefore

equivalent to using the

.BR -A " command."

Rule numbers structly smaller than 0 can be useful when more than one rule needs to be inserted

in a chain.

.TP

.B "-P, --policy"

Set the policy for the chain to the given target. The policy can be

.BR ACCEPT ", " DROP " or " RETURN .

.TP

.B "-F, --flush"

Flush the selected chain. If no chain is selected, then every chain will be

flushed. Flushing a chain does not change the policy of the

chain, however.

.TP

.B "-Z, --zero"

Set the counters of the selected chain to zero. If no chain is selected, all the counters

are set to zero. The

.B "-Z"

command can be used in conjunction with the 

.B "-L"

command.

When both the

.B "-Z"

and

.B "-L"

commands are used together in this way, the rule counters are printed on the screen

before they are set to zero.

.TP

.B "-L, --list"

List all rules in the selected chain. If no chain is selected, all chains

are listed.

.br

The following options change the output of the

.B "-L"

command.

.br

.B "--Ln"

.br

Places the rule number in front of every rule. This option is incompatible with the

.BR --Lx " option."

.br

.B "--Lc"

.br

Shows the counters at the end of each rule displayed by the

.B "-L"

command. Both a frame counter (pcnt) and a byte counter (bcnt) are displayed.

The frame counter shows how many frames have matched the specific rule, the byte

counter shows the sum of the frame sizes of these matching frames. Using this option

.BR "" "in combination with the " --Lx " option causes the counters to be written out"

.BR "" "in the '" -c " <pcnt> <bcnt>' option format."

.br

.B "--Lx"

.br

Changes the output so that it produces a set of ebtables commands that construct

the contents of the chain, when specified.

If no chain is specified, ebtables commands to construct the contents of the

table are given, including commands for creating the user-defined chains (if any).

You can use this set of commands in an ebtables boot or reload

script.  For example the output could be used at system startup.

The 

.B "--Lx"

option is incompatible with the

.B "--Ln"

listing option. Using the

.BR --Lx " option together with the " --Lc " option will cause the counters to be written out"

.BR "" "in the '" -c " <pcnt> <bcnt>' option format."

.br

.B "--Lmac2"

.br

Shows all MAC addresses with the same length, adding leading zeroes

if necessary. The default representation omits leading zeroes in the addresses.

.TP

.B "-N, --new-chain"

Create a new user-defined chain with the given name. The number of

user-defined chains is limited only by the number of possible chain names.

A user-defined chain name has a maximum

length of 31 characters. The standard policy of the user-defined chain is

ACCEPT. The policy of the new chain can be initialized to a different standard

target by using the

.B -P

command together with the

.B -N

command. In this case, the chain name does not have to be specified for the

.B -P

command.

.TP

.B "-X, --delete-chain"

Delete the specified user-defined chain. There must be no remaining references (jumps)

to the specified chain, otherwise ebtables will refuse to delete it. If no chain is

specified, all user-defined chains that aren't referenced will be removed.

.TP

.B "-E, --rename-chain"

Rename the specified chain to a new name.  Besides renaming a user-defined

chain, you can rename a standard chain to a name that suits your

taste. For example, if you like PREFORWARDING more than PREROUTING,

then you can use the -E command to rename the PREROUTING chain. If you do

rename one of the standard ebtables chain names, please be sure to mention

this fact should you post a question on the ebtables mailing lists.

It would be wise to use the standard name in your post. Renaming a standard

ebtables chain in this fashion has no effect on the structure or functioning

of the ebtables kernel table.

.TP

.B "--init-table"

Replace the current table data by the initial table data.

.TP

.B "--atomic-init"

Copy the kernel's initial data of the table to the specified

file. This can be used as the first action, after which rules are added

to the file. The file can be specified using the

.B --atomic-file

command or through the

.IR EBTABLES_ATOMIC_FILE " environment variable."

.TP

.B "--atomic-save"

Copy the kernel's current data of the table to the specified

file. This can be used as the first action, after which rules are added

to the file. The file can be specified using the

.B --atomic-file

command or through the

.IR EBTABLES_ATOMIC_FILE " environment variable."

.TP

.B "--atomic-commit"

Replace the kernel table data with the data contained in the specified

file. This is a useful command that allows you to load all your rules of a

certain table into the kernel at once, saving the kernel a lot of precious

time and allowing atomic updates of the tables. The file which contains

the table data is constructed by using either the

.B "--atomic-init"

or the

.B "--atomic-save"

command to generate a starting file. After that, using the

.B "--atomic-file"

command when constructing rules or setting the

.IR EBTABLES_ATOMIC_FILE " environment variable"

allows you to extend the file and build the complete table before

committing it to the kernel. This command can be very useful in boot scripts

to populate the ebtables tables in a fast way.

.SS MISCELLANOUS COMMANDS

.TP

.B "-V, --version"

Show the version of the ebtables userspace program.

.TP

.BR "-h, --help " "[\fIlist of module names\fP]"

Give a brief description of the command syntax. Here you can also specify

names of extensions and ebtables will try to write help about those

extensions. E.g.

.IR "ebtables -h snat log ip arp" .

Specify

.I list_extensions

to list all extensions supported by the userspace

utility.

.TP

.BR "-j, --jump " "\fItarget\fP"

The target of the rule. This is one of the following values:

.BR ACCEPT ,

.BR DROP ,

.BR CONTINUE ,

.BR RETURN ,

a target extension (see

.BR "TARGET EXTENSIONS" ")"

or a user-defined chain name.

.TP

.B --atomic-file "\fIfile\fP"

Let the command operate on the specified

.IR file .

The data of the table to

operate on will be extracted from the file and the result of the operation

will be saved back into the file. If specified, this option should come

before the command specification. An alternative that should be preferred,

is setting the

.IR EBTABLES_ATOMIC_FILE " environment variable."

.TP

.B -M, --modprobe "\fIprogram\fP"

When talking to the kernel, use this

.I program

to try to automatically load missing kernel modules.

.TP

.B --concurrent

Use a file lock to support concurrent scripts updating the ebtables kernel tables.

.SS

RULE SPECIFICATIONS

The following command line arguments make up a rule specification (as used 

in the add and delete commands). A "!" option before the specification 

inverts the test for that specification. Apart from these standard rule 

specifications there are some other command line arguments of interest.

See both the 

.BR "MATCH EXTENSIONS" 

and the

.BR "WATCHER EXTENSIONS" 

below.

.TP

.BR "-p, --protocol " "[!] \fIprotocol\fP"

The protocol that was responsible for creating the frame. This can be a

hexadecimal number, above 

.IR 0x0600 ,

a name (e.g.

.I ARP

) or

.BR LENGTH .

The protocol field of the Ethernet frame can be used to denote the

length of the header (802.2/802.3 networks). When the value of that field is

below or equals

.IR 0x0600 ,

the value equals the size of the header and shouldn't be used as a

protocol number. Instead, all frames where the protocol field is used as

the length field are assumed to be of the same 'protocol'. The protocol

name used in ebtables for these frames is

.BR LENGTH .

.br

The file

.B /etc/ethertypes

can be used to show readable

characters instead of hexadecimal numbers for the protocols. For example,

.I 0x0800

will be represented by 

.IR IPV4 .

The use of this file is not case sensitive. 

See that file for more information. The flag 

.B --proto

is an alias for this option.

.TP 

.BR "-i, --in-interface " "[!] \fIname\fP"

The interface (bridge port) via which a frame is received (this option is useful in the

.BR INPUT ,

.BR FORWARD ,

.BR PREROUTING " and " BROUTING

chains). If the interface name ends with '+', then

any interface name that begins with this name (disregarding '+') will match.

The flag

.B --in-if

is an alias for this option.

.TP

.BR "--logical-in " "[!] \fIname\fP"

The (logical) bridge interface via which a frame is received (this option is useful in the

.BR INPUT ,

.BR FORWARD ,

.BR PREROUTING " and " BROUTING

chains).

If the interface name ends with '+', then

any interface name that begins with this name (disregarding '+') will match.

.TP

.BR "-o, --out-interface " "[!] \fIname\fP"

The interface (bridge port) via which a frame is going to be sent (this option is useful in the

.BR OUTPUT ,

.B FORWARD

and

.B POSTROUTING

chains). If the interface name ends with '+', then

any interface name that begins with this name (disregarding '+') will match.

The flag

.B --out-if

is an alias for this option.

.TP

.BR "--logical-out " "[!] \fIname\fP"

The (logical) bridge interface via which a frame is going to be sent (this option

is useful in the

.BR OUTPUT ,

.B FORWARD

and

.B POSTROUTING

chains).

If the interface name ends with '+', then

any interface name that begins with this name (disregarding '+') will match.

.TP

.BR "-s, --source " "[!] \fIaddress\fP[/\fImask\fP]"

The source MAC address. Both mask and address are written as 6 hexadecimal

numbers separated by colons. Alternatively one can specify Unicast,

Multicast, Broadcast or BGA (Bridge Group Address):

.br

.IR "Unicast" "=00:00:00:00:00:00/01:00:00:00:00:00,"

.IR "Multicast" "=01:00:00:00:00:00/01:00:00:00:00:00,"

.IR "Broadcast" "=ff:ff:ff:ff:ff:ff/ff:ff:ff:ff:ff:ff or"

.IR "BGA" "=01:80:c2:00:00:00/ff:ff:ff:ff:ff:ff."

Note that a broadcast

address will also match the multicast specification. The flag

.B --src

is an alias for this option.

.TP

.BR "-d, --destination " "[!] \fIaddress\fP[/\fImask\fP]"

The destination MAC address. See

.B -s

(above) for more details on MAC addresses. The flag

.B --dst

is an alias for this option.

.TP

.BR "-c, --set-counter " "\fIpcnt bcnt\fP"

If used with

.BR -A " or " -I ", then the packet and byte counters of the new rule will be set to

.IR pcnt ", resp. " bcnt ".

If used with the

.BR -C " or " -D " commands, only rules with a packet and byte count equal to"

.IR pcnt ", resp. " bcnt " will match."

.SS MATCH EXTENSIONS

Ebtables extensions are dynamically loaded into the userspace tool,

there is therefore no need to explicitly load them with a

-m option like is done in iptables.

These extensions deal with functionality supported by kernel modules supplemental to

the core ebtables code.

.SS 802_3

Specify 802.3 DSAP/SSAP fields or SNAP type.  The protocol must be specified as

.IR "LENGTH " "(see the option " " -p " above).

.TP

.BR "--802_3-sap " "[!] \fIsap\fP"

DSAP and SSAP are two one byte 802.3 fields.  The bytes are always

equal, so only one byte (hexadecimal) is needed as an argument.

.TP

.BR "--802_3-type " "[!] \fItype\fP"

If the 802.3 DSAP and SSAP values are 0xaa then the SNAP type field must

be consulted to determine the payload protocol.  This is a two byte

(hexadecimal) argument.  Only 802.3 frames with DSAP/SSAP 0xaa are

checked for type.

.SS among

Match a MAC address or MAC/IP address pair versus a list of MAC addresses

and MAC/IP address pairs.

A list entry has the following format:

.IR xx:xx:xx:xx:xx:xx[=ip.ip.ip.ip][,] ". Multiple"

list entries are separated by a comma, specifying an IP address corresponding to

the MAC address is optional. Multiple MAC/IP address pairs with the same MAC address

but different IP address (and vice versa) can be specified. If the MAC address doesn't

match any entry from the list, the frame doesn't match the rule (unless "!" was used).

.TP

.BR "--among-dst " "[!] \fIlist\fP"

Compare the MAC destination to the given list. If the Ethernet frame has type

.IR IPv4 " or " ARP ,

then comparison with MAC/IP destination address pairs from the

list is possible.

.TP

.BR "--among-src " "[!] \fIlist\fP"

Compare the MAC source to the given list. If the Ethernet frame has type

.IR IPv4 " or " ARP ,

then comparison with MAC/IP source address pairs from the list

is possible.

.TP

.BR "--among-dst-file " "[!] \fIfile\fP"

Same as

.BR --among-dst " but the list is read in from the specified file."

.TP

.BR "--among-src-file " "[!] \fIfile\fP"

Same as

.BR --among-src " but the list is read in from the specified file."

.PP

Note that in this implementation of ebtables, among lists uses must be

internally homogeneous regarding whether IP addresses are present or not. Mixed

use of MAC addresses and MAC/IP address pairs is not supported yet.

.SS arp

Specify (R)ARP fields. The protocol must be specified as

.IR ARP " or " RARP .

.TP

.BR "--arp-opcode " "[!] \fIopcode\fP"

The (R)ARP opcode (decimal or a string, for more details see

.BR "ebtables -h arp" ).

.TP

.BR "--arp-htype " "[!] \fIhardware type\fP"

The hardware type, this can be a decimal or the string

.I Ethernet

(which sets

.I type

to 1). Most (R)ARP packets have Eternet as hardware type.

.TP

.BR "--arp-ptype " "[!] \fIprotocol type\fP"

The protocol type for which the (r)arp is used (hexadecimal or the string

.IR IPv4 ,

denoting 0x0800).

Most (R)ARP packets have protocol type IPv4.

.TP

.BR "--arp-ip-src " "[!] \fIaddress\fP[/\fImask\fP]"

The (R)ARP IP source address specification.

.TP

.BR "--arp-ip-dst " "[!] \fIaddress\fP[/\fImask\fP]"

The (R)ARP IP destination address specification.

.TP

.BR "--arp-mac-src " "[!] \fIaddress\fP[/\fImask\fP]"

The (R)ARP MAC source address specification.

.TP

.BR "--arp-mac-dst " "[!] \fIaddress\fP[/\fImask\fP]"

The (R)ARP MAC destination address specification.

.TP

.BR "" "[!]" " --arp-gratuitous"

Checks for ARP gratuitous packets: checks equality of IPv4 source

address and IPv4 destination address inside the ARP header.

.SS ip

Specify IPv4 fields. The protocol must be specified as

.IR IPv4 .

.TP

.BR "--ip-source " "[!] \fIaddress\fP[/\fImask\fP]"

The source IP address.

The flag

.B --ip-src

is an alias for this option.

.TP

.BR "--ip-destination " "[!] \fIaddress\fP[/\fImask\fP]"

The destination IP address.

The flag

.B --ip-dst

is an alias for this option.

.TP

.BR "--ip-tos " "[!] \fItos\fP"

The IP type of service, in hexadecimal numbers.

.BR IPv4 .

.TP

.BR "--ip-protocol " "[!] \fIprotocol\fP"

The IP protocol.

The flag

.B --ip-proto

is an alias for this option.

.TP

.BR "--ip-source-port " "[!] \fIport1\fP[:\fIport2\fP]"

The source port or port range for the IP protocols 6 (TCP), 17

(UDP), 33 (DCCP) or 132 (SCTP). The

.B --ip-protocol

option must be specified as

.IR TCP ", " UDP ", " DCCP " or " SCTP .

If

.IR port1 " is omitted, " 0:port2 " is used; if " port2 " is omitted but a colon is specified, " port1:65535 " is used."

The flag

.B --ip-sport

is an alias for this option.

.TP

.BR "--ip-destination-port " "[!] \fIport1\fP[:\fIport2\fP]"

The destination port or port range for ip protocols 6 (TCP), 17

(UDP), 33 (DCCP) or 132 (SCTP). The

.B --ip-protocol

option must be specified as

.IR TCP ", " UDP ", " DCCP " or " SCTP .

If

.IR port1 " is omitted, " 0:port2 " is used; if " port2 " is omitted but a colon is specified, " port1:65535 " is used."

The flag

.B --ip-dport

is an alias for this option.

.SS ip6

Specify IPv6 fields. The protocol must be specified as

.IR IPv6 .

.TP

.BR "--ip6-source " "[!] \fIaddress\fP[/\fImask\fP]"

The source IPv6 address.

The flag

.B --ip6-src

is an alias for this option.

.TP

.BR "--ip6-destination " "[!] \fIaddress\fP[/\fImask\fP]"

The destination IPv6 address.

The flag

.B --ip6-dst

is an alias for this option.

.TP

.BR "--ip6-tclass " "[!] \fItclass\fP"

The IPv6 traffic class, in hexadecimal numbers.

.TP

.BR "--ip6-protocol " "[!] \fIprotocol\fP"

The IP protocol.

The flag

.B --ip6-proto

is an alias for this option.

.TP

.BR "--ip6-source-port " "[!] \fIport1\fP[:\fIport2\fP]"

The source port or port range for the IPv6 protocols 6 (TCP), 17

(UDP), 33 (DCCP) or 132 (SCTP). The

.B --ip6-protocol

option must be specified as

.IR TCP ", " UDP ", " DCCP " or " SCTP .

If

.IR port1 " is omitted, " 0:port2 " is used; if " port2 " is omitted but a colon is specified, " port1:65535 " is used."

The flag

.B --ip6-sport

is an alias for this option.

.TP

.BR "--ip6-destination-port " "[!] \fIport1\fP[:\fIport2\fP]"

The destination port or port range for IPv6 protocols 6 (TCP), 17

(UDP), 33 (DCCP) or 132 (SCTP). The

.B --ip6-protocol

option must be specified as

.IR TCP ", " UDP ", " DCCP " or " SCTP .

If

.IR port1 " is omitted, " 0:port2 " is used; if " port2 " is omitted but a colon is specified, " port1:65535 " is used."

The flag

.B --ip6-dport

is an alias for this option.

.TP

.BR "--ip6-icmp-type " "[!] {\fItype\fP[:\fItype\fP]/\fIcode\fP[:\fIcode\fP]|\fItypename\fP}"

Specify ipv6\-icmp type and code to match.

Ranges for both type and code are supported. Type and code are

separated by a slash. Valid numbers for type and range are 0 to 255.

To match a single type including all valid codes, symbolic names can

be used instead of numbers. The list of known type names is shown by the command

.nf

  ebtables \-\-help ip6

.fi

This option is only valid for \-\-ip6-prococol ipv6-icmp.

.SS limit

This module matches at a limited rate using a token bucket filter.

A rule using this extension will match until this limit is reached.

It can be used with the

.B --log

watcher to give limited logging, for example. Its use is the same

as the limit match of iptables.

.TP

.BR "--limit " "[\fIvalue\fP]"

Maximum average matching rate: specified as a number, with an optional

.IR /second ", " /minute ", " /hour ", or " /day " suffix; the default is " 3/hour .

.TP

.BR "--limit-burst " "[\fInumber\fP]"

Maximum initial number of packets to match: this number gets recharged by

one every time the limit specified above is not reached, up to this

number; the default is

.IR 5 .

.SS mark_m

.TP

.BR "--mark " "[!] [\fIvalue\fP][/\fImask\fP]"

Matches frames with the given unsigned mark value. If a

.IR value " and " mask " are specified, the logical AND of the mark value of the frame and"

the user-specified

.IR mask " is taken before comparing it with the"

user-specified mark

.IR value ". When only a mark "

.IR value " is specified, the packet"

only matches when the mark value of the frame equals the user-specified

mark

.IR value .

If only a

.IR mask " is specified, the logical"

AND of the mark value of the frame and the user-specified

.IR mask " is taken and the frame matches when the result of this logical AND is"

non-zero. Only specifying a

.IR mask " is useful to match multiple mark values."

.SS pkttype

.TP

.BR "--pkttype-type " "[!] \fItype\fP"

Matches on the Ethernet "class" of the frame, which is determined by the

generic networking code. Possible values:

.IR broadcast " (MAC destination is the broadcast address),"

.IR multicast " (MAC destination is a multicast address),"

.IR host " (MAC destination is the receiving network device), or "

.IR otherhost " (none of the above)."

.SS stp

Specify stp BPDU (bridge protocol data unit) fields. The destination

address

.BR "" ( -d ") must be specified as the bridge group address"

.IR "" ( BGA ).

For all options for which a range of values can be specified, it holds that

if the lower bound is omitted (but the colon is not), then the lowest possible lower bound

for that option is used, while if the upper bound is omitted (but the colon again is not), the

highest possible upper bound for that option is used.

.TP

.BR "--stp-type " "[!] \fItype\fP"

The BPDU type (0-255), recognized non-numerical types are

.IR config ", denoting a configuration BPDU (=0), and"

.IR tcn ", denothing a topology change notification BPDU (=128)."

.TP

.BR "--stp-flags " "[!] \fIflag\fP"

The BPDU flag (0-255), recognized non-numerical flags are

.IR topology-change ", denoting the topology change flag (=1), and"

.IR topology-change-ack ", denoting the topology change acknowledgement flag (=128)."

.TP

.BR "--stp-root-prio " "[!] [\fIprio\fP][:\fIprio\fP]"

The root priority (0-65535) range.

.TP

.BR "--stp-root-addr " "[!] [\fIaddress\fP][/\fImask\fP]"

The root mac address, see the option

.BR -s " for more details."

.TP

.BR "--stp-root-cost " "[!] [\fIcost\fP][:\fIcost\fP]"

The root path cost (0-4294967295) range.

.TP

.BR "--stp-sender-prio " "[!] [\fIprio\fP][:\fIprio\fP]"

The BPDU's sender priority (0-65535) range.

.TP

.BR "--stp-sender-addr " "[!] [\fIaddress\fP][/\fImask\fP]"

The BPDU's sender mac address, see the option

.BR -s " for more details."

.TP

.BR "--stp-port " "[!] [\fIport\fP][:\fIport\fP]"

The port identifier (0-65535) range.

.TP

.BR "--stp-msg-age " "[!] [\fIage\fP][:\fIage\fP]"

The message age timer (0-65535) range.

.TP

.BR "--stp-max-age " "[!] [\fIage\fP][:\fIage\fP]"

The max age timer (0-65535) range.

.TP

.BR "--stp-hello-time " "[!] [\fItime\fP][:\fItime\fP]"

The hello time timer (0-65535) range.

.TP

.BR "--stp-forward-delay " "[!] [\fIdelay\fP][:\fIdelay\fP]"

The forward delay timer (0-65535) range.

.\" .SS string

.\" This module matches on a given string using some pattern matching strategy.

.\" .TP

.\" .BR "--string-algo " "\fIalgorithm\fP"

.\" The pattern matching strategy. (bm = Boyer-Moore, kmp = Knuth-Pratt-Morris)

.\" .TP

.\" .BR "--string-from " "\fIoffset\fP"

.\" The lowest offset from which a match can start. (default: 0)

.\" .TP

.\" .BR "--string-to " "\fIoffset\fP"

.\" The highest offset from which a match can start. (default: size of frame)

.\" .TP

.\" .BR "--string " "[!] \fIpattern\fP"

.\" Matches the given pattern.

.\" .TP

.\" .BR "--string-hex " "[!] \fIpattern\fP"

.\" Matches the given pattern in hex notation, e.g. '|0D 0A|', '|0D0A|', 'www|09|netfilter|03|org|00|'

.\" .TP

.\" .BR "--string-icase"

.\" Ignore case when searching.

.SS vlan

Specify 802.1Q Tag Control Information fields.

The protocol must be specified as

.IR 802_1Q " (0x8100)."

.TP

.BR "--vlan-id " "[!] \fIid\fP"

The VLAN identifier field (VID). Decimal number from 0 to 4095.

.TP

.BR "--vlan-prio " "[!] \fIprio\fP"

The user priority field, a decimal number from 0 to 7.

The VID should be set to 0 ("null VID") or unspecified

(in the latter case the VID is deliberately set to 0).

.TP

.BR "--vlan-encap " "[!] \fItype\fP"

The encapsulated Ethernet frame type/length.

Specified as a hexadecimal

number from 0x0000 to 0xFFFF or as a symbolic name

from

.BR /etc/ethertypes .

.SS WATCHER EXTENSIONS

Watchers only look at frames passing by, they don't modify them nor decide

to accept the frames or not. These watchers only

see the frame if the frame matches the rule, and they see it before the

target is executed.

.SS log

The log watcher writes descriptive data about a frame to the syslog.

.TP

.B "--log"

.br

Log with the default loggin options: log-level=

.IR info ,

log-prefix="", no ip logging, no arp logging.

.TP

.B --log-level "\fIlevel\fP"

.br

Defines the logging level. For the possible values, see

.BR "ebtables -h log" .

The default level is 

.IR info .

.TP

.BR --log-prefix " \fItext\fP"

.br

Defines the prefix

.I text

to be printed at the beginning of the line with the logging information.

.TP

.B --log-ip 

.br

Will log the ip information when a frame made by the ip protocol matches 

the rule. The default is no ip information logging.

.TP

.B --log-ip6 

.br

Will log the ipv6 information when a frame made by the ipv6 protocol matches 

the rule. The default is no ipv6 information logging.

.TP

.B --log-arp

.br

Will log the (r)arp information when a frame made by the (r)arp protocols

matches the rule. The default is no (r)arp information logging.

.SS nflog

The nflog watcher passes the packet to the loaded logging backend