Bridge Firewall Configuration

Note

Documentation under development

Overview

In this section there’s useful information of all firewall configuration that can be done regarding bridge, and appropiate op-mode commands. Configuration commands covered in this section:

set firewall bridge …

From main structure defined in Firewall Overview in this section you can find detailed information only for the next part of the general structure:

- set firewall
    * bridge
         - forward
            + filter
         - name
            + custom_name

Traffic which is received by the router on an interface which is member of a bridge is processed on the Bridge Layer. A simplified packet flow diagram for this layer is shown next:

../../_images/firewall-bridge-packet-flow.png

For traffic that needs to be forwared internally by the bridge, base chain is is forward, and it’s base command for filtering is set firewall bridge forward filter ..., which happens in stage 4, highlightened with red color.

Custom bridge firewall chains can be create with command set firewall bridge name <name> .... In order to use such custom chain, a rule with action jump, and the appropiate target should be defined in a base chain.

Note

Layer 3 bridge: When an IP address is assigned to the bridge interface, and if traffic is sent to the router to this IP (for example using such IP as default gateway), then rules defined for bridge firewall won’t match, and firewall analysis continues at IP layer.

Bridge Rules

For firewall filtering, firewall rules needs to be created. Each rule is numbered, has an action to apply if the rule is matched, and the ability to specify multiple criteria matchers. Data packets go through the rules from 1 - 999999, so order is crucial. At the first match the action of the rule will be executed.

Actions

If a rule is defined, then an action must be defined for it. This tells the firewall what to do if all criteria matchers defined for such rule do match.

In firewall bridge rules, the action can be:

accept: accept the packet.

continue: continue parsing next rule.

drop: drop the packet.

jump: jump to another custom chain.

return: Return from the current chain and continue at the next rule of the last chain.

queue: Enqueue packet to userspace.

This required setting defines the action of the current rule. If action is set to jump, then jump-target is also needed.

set firewall bridge forward filter rule <1-999999> jump-target <text>

set firewall bridge name <name> rule <1-999999> jump-target <text>

set firewall bridge forward filter rule <1-999999> queue <0-65535>

set firewall bridge name <name> rule <1-999999> queue <0-65535>

To be used only when action is set to queue. Use this command to specify queue target to use. Queue range is also supported.

set firewall bridge forward filter rule <1-999999> queue-options bypass

set firewall bridge name <name> rule <1-999999> queue-options bypass

To be used only when action is set to queue. Use this command to let packet go through firewall when no userspace software is connected to the queue.

set firewall bridge forward filter rule <1-999999> queue-options fanout

set firewall bridge name <name> rule <1-999999> queue-options fanout

To be used only when action is set to queue. Use this command to distribute packets between several queues.

Also, default-action is an action that takes place whenever a packet does not match any rule in it’s chain. For base chains, possible options for default-action are accept or drop.

set firewall bridge forward filter default-action [accept | drop]

This set the default action of the rule-set if no rule matched a packet criteria. If default-action is set to jump, then default-jump-target is also needed. Note that for base chains, default action can only be set to accept or drop, while on custom chain, more actions are available.

set firewall bridge name <name> default-jump-target <text>

To be used only when defult-action is set to jump. Use this command to specify jump target for default rule.

Note

Important note about default-actions: If default action for any base chain is not defined, then the default action is set to accept for that chain. For custom chains, if default action is not defined, then the default-action is set to drop.

Firewall Logs

Logging can be enable for every single firewall rule. If enabled, other log options can be defined.

set firewall bridge forward filter rule <1-999999> log

set firewall bridge name <name> rule <1-999999> log

Enable logging for the matched packet. If this configuration command is not present, then log is not enabled.

set firewall bridge forward filter enable-default-log

set firewall bridge name <name> enable-default-log

Use this command to enable the logging of the default action on the specified chain.

Define log-level. Only applicable if rule log is enable.

set firewall bridge forward filter rule <1-999999> log-options group <0-65535>

set firewall bridge name <name> rule <1-999999> log-options group <0-65535>

Define log group to send message to. Only applicable if rule log is enable.

set firewall bridge forward filter rule <1-999999> log-options snapshot-length <0-9000>

set firewall bridge name <name> rule <1-999999> log-options snapshot-length <0-9000>

Define length of packet payload to include in netlink message. Only applicable if rule log is enable and log group is defined.

set firewall bridge forward filter rule <1-999999> log-options queue-threshold <0-65535>

set firewall bridge name <name> rule <1-999999> log-options queue-threshold <0-65535>

Define number of packets to queue inside the kernel before sending them to userspace. Only applicable if rule log is enable and log group is defined.

Firewall Description

For reference, a description can be defined for every defined custom chain.

set firewall bridge name <name> description <text>

Provide a rule-set description to a custom firewall chain.

Rule Status

When defining a rule, it is enable by default. In some cases, it is useful to just disable the rule, rather than removing it.

set firewall bridge forward filter rule <1-999999> disable

set firewall bridge name <name> rule <1-999999> disable

Command for disabling a rule but keep it in the configuration.

Matching criteria

There are a lot of matching criteria against which the packet can be tested.

set firewall bridge forward filter rule <1-999999> destination mac-address <mac-address>

set firewall bridge name <name> rule <1-999999> destination mac-address <mac-address>

set firewall bridge forward filter rule <1-999999> source mac-address <mac-address>

set firewall bridge name <name> rule <1-999999> source mac-address <mac-address>

Match criteria based on source and/or destination mac-address.

set firewall bridge forward filter rule <1-999999> inbound-interface name <iface>

set firewall bridge name <name> rule <1-999999> inbound-interface name <iface>

Match based on inbound interface. Wilcard * can be used. For example: eth2*. Prepending character ! for inverted matching criteria is also supportd. For example !eth2

set firewall bridge forward filter rule <1-999999> inbound-interface group <iface_group>

set firewall bridge name <name> rule <1-999999> inbound-interface group <iface_group>

Match based on inbound interface group. Prepending character ! for inverted matching criteria is also supportd. For example !IFACE_GROUP

set firewall bridge forward filter rule <1-999999> outbound-interface name <iface>

set firewall bridge name <name> rule <1-999999> outbound-interface name <iface>

Match based on outbound interface. Wilcard * can be used. For example: eth2*. Prepending character ! for inverted matching criteria is also supportd. For example !eth2

set firewall bridge forward filter rule <1-999999> outbound-interface group <iface_group>

set firewall bridge name <name> rule <1-999999> outbound-interface group <iface_group>

Match based on outbound interface group. Prepending character ! for inverted matching criteria is also supportd. For example !IFACE_GROUP

set firewall bridge forward filter rule <1-999999> vlan id <0-4096>

set firewall bridge name <name> rule <1-999999> vlan id <0-4096>

Match based on vlan ID. Range is also supported.

set firewall bridge forward filter rule <1-999999> vlan priority <0-7>

set firewall bridge name <name> rule <1-999999> vlan priority <0-7>

Match based on vlan priority(pcp). Range is also supported.

Operation-mode Firewall

Rule-set overview

In this section you can find all useful firewall op-mode commands.

General commands for firewall configuration, counter and statiscits:

show firewall

show firewall summary

show firewall statistics

And, to print only bridge firewall information:

show firewall bridge

show firewall bridge forward filter

show firewall bridge forward filter rule <rule>

show firewall bridge name <name>

show firewall bridge name <name> rule <rule>

Show Firewall log

show log firewall

show log firewall bridge

show log firewall bridge forward

show log firewall bridge forward filter

show log firewall bridge name <name>

show log firewall bridge forward filter rule <rule>

show log firewall bridge name <name> rule <rule>

Show the logs of all firewall; show all bridge firewall logs; show all logs for forward hook; show all logs for forward hook and priority filter; show all logs for particular custom chain; show logs for specific Rule-Set.

Example

Configuration example:

set firewall bridge forward filter default-action 'drop'
set firewall bridge forward filter enable-default-log
set firewall bridge forward filter rule 10 action 'continue'
set firewall bridge forward filter rule 10 inbound-interface name 'eth2'
set firewall bridge forward filter rule 10 vlan id '22'
set firewall bridge forward filter rule 20 action 'drop'
set firewall bridge forward filter rule 20 inbound-interface group 'TRUNK-RIGHT'
set firewall bridge forward filter rule 20 vlan id '60'
set firewall bridge forward filter rule 30 action 'jump'
set firewall bridge forward filter rule 30 jump-target 'TEST'
set firewall bridge forward filter rule 30 outbound-interface name '!eth1'
set firewall bridge forward filter rule 35 action 'accept'
set firewall bridge forward filter rule 35 vlan id '11'
set firewall bridge forward filter rule 40 action 'continue'
set firewall bridge forward filter rule 40 destination mac-address '66:55:44:33:22:11'
set firewall bridge forward filter rule 40 source mac-address '11:22:33:44:55:66'
set firewall bridge name TEST default-action 'accept'
set firewall bridge name TEST enable-default-log
set firewall bridge name TEST rule 10 action 'continue'
set firewall bridge name TEST rule 10 log
set firewall bridge name TEST rule 10 vlan priority '0'

And op-mode commands:

vyos@BRI:~$ show firewall bridge
Rulesets bridge Information

---------------------------------
bridge Firewall "forward filter"

Rule     Action    Protocol      Packets    Bytes  Conditions
-------  --------  ----------  ---------  -------  ---------------------------------------------------------------------
10       continue  all                 0        0  iifname "eth2" vlan id 22  continue
20       drop      all                 0        0  iifname @I_TRUNK-RIGHT vlan id 60
30       jump      all              2130   170688  oifname != "eth1"  jump NAME_TEST
35       accept    all              2080   168616  vlan id 11  accept
40       continue  all                 0        0  ether daddr 66:55:44:33:22:11 ether saddr 11:22:33:44:55:66  continue
default  drop      all                 0        0

---------------------------------
bridge Firewall "name TEST"

Rule     Action    Protocol      Packets    Bytes  Conditions
-------  --------  ----------  ---------  -------  --------------------------------------------------
10       continue  all              2130   170688  vlan pcp 0  prefix "[bri-NAM-TEST-10-C]"  continue
default  accept    all              2130   170688

vyos@BRI:~$
vyos@BRI:~$ show firewall bridge name TEST
Ruleset Information

---------------------------------
bridge Firewall "name TEST"

Rule     Action    Protocol      Packets    Bytes  Conditions
-------  --------  ----------  ---------  -------  --------------------------------------------------
10       continue  all              2130   170688  vlan pcp 0  prefix "[bri-NAM-TEST-10-C]"  continue
default  accept    all              2130   170688

vyos@BRI:~$

Inspect logs:

vyos@BRI:~$ show log firewall bridge
Dec 05 14:37:47 kernel: [bri-NAM-TEST-10-C]IN=eth1 OUT=eth2 ARP HTYPE=1 PTYPE=0x0800 OPCODE=1 MACSRC=50:00:00:04:00:00 IPSRC=10.11.11.101 MACDST=00:00:00:00:00:00 IPDST=10.11.11.102
Dec 05 14:37:48 kernel: [bri-NAM-TEST-10-C]IN=eth1 OUT=eth2 ARP HTYPE=1 PTYPE=0x0800 OPCODE=1 MACSRC=50:00:00:04:00:00 IPSRC=10.11.11.101 MACDST=00:00:00:00:00:00 IPDST=10.11.11.102
Dec 05 14:37:49 kernel: [bri-NAM-TEST-10-C]IN=eth1 OUT=eth2 ARP HTYPE=1 PTYPE=0x0800 OPCODE=1 MACSRC=50:00:00:04:00:00 IPSRC=10.11.11.101 MACDST=00:00:00:00:00:00 IPDST=10.11.11.102
...
vyos@BRI:~$ show log firewall bridge forward filter
Dec 05 14:42:22 kernel: [bri-FWD-filter-default-D]IN=eth2 OUT=eth1 MAC=33:33:00:00:00:16:50:00:00:06:00:00:86:dd SRC=0000:0000:0000:0000:0000:0000:0000:0000 DST=ff02:0000:0000:0000:0000:0000:0000:0016 LEN=96 TC=0 HOPLIMIT=1 FLOWLBL=0 PROTO=ICMPv6 TYPE=143 CODE=0
Dec 05 14:42:22 kernel: [bri-FWD-filter-default-D]IN=eth2 OUT=eth1 MAC=33:33:00:00:00:16:50:00:00:06:00:00:86:dd SRC=0000:0000:0000:0000:0000:0000:0000:0000 DST=ff02:0000:0000:0000:0000:0000:0000:0016 LEN=96 TC=0 HOPLIMIT=1 FLOWLBL=0 PROTO=ICMPv6 TYPE=143 CODE=0