:lastproofread: 2021-06-29 .. _firewall: ######## Firewall ######## ******** Overview ******** VyOS makes use of Linux `netfilter `_ for packet filtering. The firewall supports the creation of groups for ports, addresses, and networks (implemented using netfilter ipset) and the option of interface or zone based firewall policy. .. note:: **Important note on usage of terms:** The firewall makes use of the terms `in`, `out`, and `local` for firewall policy. Users experienced with netfilter often confuse `in` to be a reference to the `INPUT` chain, and `out` the `OUTPUT` chain from netfilter. This is not the case. These instead indicate the use of the `FORWARD` chain and either the input or output interface. The `INPUT` chain, which is used for local traffic to the OS, is a reference to as `local` with respect to its input interface. *************** Global settings *************** Some firewall settings are global and have an affect on the whole system. .. cfgcmd:: set firewall all-ping [enable | disable] By default, when VyOS receives an ICMP echo request packet destined for itself, it will answer with an ICMP echo reply, unless you avoid it through its firewall. With the firewall you can set rules to accept, drop or reject ICMP in, out or local traffic. You can also use the general **firewall all-ping** command. This command affects only to LOCAL (packets destined for your VyOS system), not to IN or OUT traffic. .. note:: **firewall all-ping** affects only to LOCAL and it always behaves in the most restrictive way .. code-block:: none set firewall all-ping enable When the command above is set, VyOS will answer every ICMP echo request addressed to itself, but that will only happen if no other rule is applied dropping or rejecting local echo requests. In case of conflict, VyOS will not answer ICMP echo requests. .. code-block:: none set firewall all-ping disable When the command above is set, VyOS will answer no ICMP echo request addressed to itself at all, no matter where it comes from or whether more specific rules are being applied to accept them. .. cfgcmd:: set firewall broadcast-ping [enable | disable] This setting enable or disable the response of icmp broadcast messages. The following system parameter will be altered: * ``net.ipv4.icmp_echo_ignore_broadcasts`` .. cfgcmd:: set firewall ip-src-route [enable | disable] .. cfgcmd:: set firewall ipv6-src-route [enable | disable] This setting handle if VyOS accept packets with a source route option. The following system parameter will be altered: * ``net.ipv4.conf.all.accept_source_route`` * ``net.ipv6.conf.all.accept_source_route`` .. cfgcmd:: set firewall receive-redirects [enable | disable] .. cfgcmd:: set firewall ipv6-receive-redirects [enable | disable] enable or disable of ICMPv4 or ICMPv6 redirect messages accepted by VyOS. The following system parameter will be altered: * ``net.ipv4.conf.all.accept_redirects`` * ``net.ipv6.conf.all.accept_redirects`` .. cfgcmd:: set firewall send-redirects [enable | disable] enable or disable ICMPv4 redirect messages send by VyOS The following system parameter will be altered: * ``net.ipv4.conf.all.send_redirects`` .. cfgcmd:: set firewall log-martians [enable | disable] enable or disable the logging of martian IPv4 packets. The following system parameter will be altered: * ``net.ipv4.conf.all.log_martians`` .. cfgcmd:: set firewall source-validation [strict | loose | disable] Set the IPv4 source validation mode. The following system parameter will be altered: * ``net.ipv4.conf.all.rp_filter`` .. cfgcmd:: set firewall syn-cookies [enable | disable] Enable or Disable if VyOS use IPv4 TCP SYN Cookies. The following system parameter will be altered: * ``net.ipv4.tcp_syncookies`` .. cfgcmd:: set firewall twa-hazards-protection [enable | disable] Enable or Disable VyOS to be :rfc:`1337` conform. The following system parameter will be altered: * ``net.ipv4.tcp_rfc1337`` .. cfgcmd:: set firewall state-policy established action [accept | drop | reject] .. cfgcmd:: set firewall state-policy established log enable Set the global setting for an established connection. .. cfgcmd:: set firewall state-policy invalid action [accept | drop | reject] .. cfgcmd:: set firewall state-policy invalid log enable Set the global setting for invalid packets. .. cfgcmd:: set firewall state-policy related action [accept | drop | reject] .. cfgcmd:: set firewall state-policy related log enable Set the global setting for related connections. ****** Groups ****** Firewall groups represent collections of IP addresses, networks, or ports. Once created, a group can be referenced by firewall rules as either a source or destination. Members can be added or removed from a group without changes to, or the need to reload, individual firewall rules. .. note:: Groups can also be referenced by NAT configuration. Groups need to have unique names. Even though some contain IPv4 addresses and others contain IPv6 addresses, they still need to have unique names, so you may want to append "-v4" or "-v6" to your group names. Address Groups ============== In an **address group** a single IP address or IP address ranges are defined. .. cfgcmd:: set firewall group address-group address [address | address range] .. cfgcmd:: set firewall group ipv6-address-group address
Define a IPv4 or a IPv6 address group .. code-block:: none set firewall group address-group ADR-INSIDE-v4 address 192.168.0.1 set firewall group address-group ADR-INSIDE-v4 address 10.0.0.1-10.0.0.8 set firewall group ipv6-address-group ADR-INSIDE-v6 address 2001:db8::1 .. cfgcmd:: set firewall group address-group description .. cfgcmd:: set firewall group ipv6-address-group description Provide a IPv4 or IPv6 address group description Network Groups ============== While **network groups** accept IP networks in CIDR notation, specific IP addresses can be added as a 32-bit prefix. If you foresee the need to add a mix of addresses and networks, the network group is recommended. .. cfgcmd:: set firewall group network-group network .. cfgcmd:: set firewall group ipv6-network-group network Define a IPv4 or IPv6 Network group. .. code-block:: none set firewall group network-group NET-INSIDE-v4 network 192.168.0.0/24 set firewall group network-group NET-INSIDE-v4 network 192.168.1.0/24 set firewall group ipv6-network-group NET-INSIDE-v6 network 2001:db8::/64 .. cfgcmd:: set firewall group network-group description .. cfgcmd:: set firewall group ipv6-network-group description Provide a IPv4 or IPv6 network group description. Port Groups =========== A **port group** represents only port numbers, not the protocol. Port groups can be referenced for either TCP or UDP. It is recommended that TCP and UDP groups are created separately to avoid accidentally filtering unnecessary ports. Ranges of ports can be specified by using `-`. .. cfgcmd:: set firewall group port-group port [portname | portnumber | startport-endport] Define a port group. A port name can be any name defined in /etc/services. e.g.: http .. code-block:: none set firewall group port-group PORT-TCP-SERVER1 port http set firewall group port-group PORT-TCP-SERVER1 port 443 set firewall group port-group PORT-TCP-SERVER1 port 5000-5010 .. cfgcmd:: set firewall group port-group description Provide a port group description. ********* Rule-Sets ********* A rule-set is a named collection of firewall rules that can be applied to an interface or a zone. Each rule is numbered, has an action to apply if the rule is matched, and the ability to specify the criteria to match. Data packets go through the rules from 1 - 9999, at the first match the action of the rule will be executed. .. cfgcmd:: set firewall name description .. cfgcmd:: set firewall ipv6-name description Provide a rule-set description. .. cfgcmd:: set firewall name default-action [drop | reject | accept] .. cfgcmd:: set firewall ipv6-name default-action [drop | reject | accept] This set the default action of the rule-set if no rule matched a packet criteria. .. cfgcmd:: set firewall name enable-default-log .. cfgcmd:: set firewall ipv6-name enable-default-log Use this command to enable the logging of the default action. .. cfgcmd:: set firewall name rule <1-9999> action [drop | reject | accept] .. cfgcmd:: set firewall ipv6-name rule <1-9999> action [drop | reject | accept] This required setting defines the action of the current rule. .. cfgcmd:: set firewall name rule <1-9999> description .. cfgcmd:: set firewall ipv6-name rule <1-9999> description Provide a description for each rule. .. cfgcmd:: set firewall name rule <1-9999> log [disable | enable] .. cfgcmd:: set firewall ipv6-name rule <1-9999> log [disable | enable] Enable or disable logging for the matched packet. .. cfgcmd:: set firewall name rule <1-9999> disable .. cfgcmd:: set firewall ipv6-name rule <1-9999> disable If you want to disable a rule but let it in the configuration. Matching criteria ================= There are a lot of matching criteria against which the package can be tested. .. cfgcmd:: set firewall name rule <1-9999> source address [address | addressrange | CIDR] .. cfgcmd:: set firewall name rule <1-9999> destination address [address | addressrange | CIDR] .. cfgcmd:: set firewall ipv6-name rule <1-9999> source address [address | addressrange | CIDR] .. cfgcmd:: set firewall ipv6-name rule <1-9999> destination address [address | addressrange | CIDR] This is similar to the network groups part, but here you are able to negate the matching addresses. .. code-block:: none set firewall name WAN-IN-v4 rule 100 source address 192.0.2.10-192.0.2.11 # with a '!' the rule match everything except the specified subnet set firewall name WAN-IN-v4 rule 101 source address !203.0.113.0/24 set firewall ipv6-name WAN-IN-v6 rule 100 source address 2001:db8::202 .. cfgcmd:: set firewall name rule <1-9999> source mac-address .. cfgcmd:: set firewall ipv6-name rule <1-9999> source mac-address Only in the source criteria, you can specify a mac-address. .. code-block:: none set firewall name LAN-IN-v4 rule 100 source mac-address 00:53:00:11:22:33 set firewall name LAN-IN-v4 rule 101 source mac-address !00:53:00:aa:12:34 .. cfgcmd:: set firewall name rule <1-9999> source port [1-65535 | portname | start-end] .. cfgcmd:: set firewall name rule <1-9999> destination port [1-65535 | portname | start-end] .. cfgcmd:: set firewall ipv6-name rule <1-9999> source port [1-65535 | portname | start-end] .. cfgcmd:: set firewall ipv6-name rule <1-9999> destination port [1-65535 | portname | start-end] A port can be set with a port number or a name which is here defined: ``/etc/services``. .. code-block:: none set firewall name WAN-IN-v4 rule 10 source port '22' set firewall name WAN-IN-v4 rule 11 source port '!http' set firewall name WAN-IN-v4 rule 12 source port 'https' Multiple source ports can be specified as a comma-separated list. The whole list can also be "negated" using '!'. For example: .. code-block:: none set firewall ipv6-name WAN-IN-v6 rule 10 source port '!22,https,3333-3338' .. cfgcmd:: set firewall name rule <1-9999> source group address-group .. cfgcmd:: set firewall name rule <1-9999> destination group address-group .. cfgcmd:: set firewall ipv6-name rule <1-9999> source group address-group .. cfgcmd:: set firewall ipv6-name rule <1-9999> destination group address-group Use a specific address-group .. cfgcmd:: set firewall name rule <1-9999> source group network-group .. cfgcmd:: set firewall name rule <1-9999> destination group network-group .. cfgcmd:: set firewall ipv6-name rule <1-9999> source group network-group .. cfgcmd:: set firewall ipv6-name rule <1-9999> destination group network-group Use a specific network-group .. cfgcmd:: set firewall name rule <1-9999> source group port-group .. cfgcmd:: set firewall name rule <1-9999> destination group port-group .. cfgcmd:: set firewall ipv6-name rule <1-9999> source group port-group .. cfgcmd:: set firewall ipv6-name rule <1-9999> destination group port-group Use a specific port-group .. cfgcmd:: set firewall name rule <1-9999> protocol [ | <0-255> | all | tcp_udp] .. cfgcmd:: set firewall ipv6-name rule <1-9999> protocol [ | <0-255> | all | tcp_udp] Match a protocol criteria. A protocol number or a name which is here defined: ``/etc/protocols``. Special names are ``all`` for all protocols and ``tcp_udp`` for tcp and udp based packets. The ``!`` negate the selected protocol. .. code-block:: none set firewall name WAN-IN-v4 rule 10 protocol tcp_udp set firewall name WAN-IN-v4 rule 11 protocol !tcp_udp set firewall ipv6-name WAN-IN-v6 rule 10 protocol tcp .. cfgcmd:: set firewall name rule <1-9999> tcp flags .. cfgcmd:: set firewall ipv6-name rule <1-9999> tcp flags Allowed values fpr TCP flags: ``SYN``, ``ACK``, ``FIN``, ``RST``, ``URG``, ``PSH``, ``ALL`` When specifying more than one flag, flags should be comma separated. The ``!`` negate the selected protocol. .. code-block:: none set firewall name WAN-IN-v4 rule 10 tcp flags 'ACK' set firewall name WAN-IN-v4 rule 12 tcp flags 'SYN' set firewall name WAN-IN-v4 rule 13 tcp flags 'SYN,!ACK,!FIN,!RST' .. cfgcmd:: set firewall name rule <1-9999> state [established | invalid | new | related] [enable | disable] .. cfgcmd:: set firewall ipv6-name rule <1-9999> state [established | invalid | new | related] [enable | disable] Match against the state of a packet. *********************************** Applying a Rule-Set to an Interface *********************************** A Rule-Set can be applied to every interface: * ``in``: Ruleset for forwarded packets on an inbound interface * ``out``: Ruleset for forwarded packets on an outbound interface * ``local``: Ruleset for packets destined for this router .. cfgcmd:: set interface ethernet firewall [in | out | local] [name | ipv6-name] Here are some examples for applying a rule-set to an interface .. code-block:: none set interface ethernet eth1 vif 100 firewall in name LANv4-IN set interface ethernet eth1 vif 100 firewall out name LANv4-OUT set interface bonding bond0 firewall in name LANv4-IN set interfaces openvpn vtun1 firewall in name Lanv4-IN .. note:: As you can see in the example here, you can assign the same rule-set to several interfaces. An interface can only have one rule-set per chain. ************************** Zone-based Firewall Policy ************************** As an alternative to applying policy to an interface directly, a zone-based firewall can be created to simplify configuration when multiple interfaces belong to the same security zone. Instead of applying rule-sets to interfaces, they are applied to source zone-destination zone pairs. An basic introduction to zone-based firewalls can be found `here `_, and an example at :ref:`examples-zone-policy`. Define a Zone ============= To define a zone setup either one with interfaces or a local zone. .. cfgcmd:: set zone-policy zone interface Set interfaces to a zone. A zone can have multiple interfaces. But an interface can only be a member in one zone. .. cfgcmd:: set zone-policy zone local-zone Define the zone as a local zone. A local zone has no interfaces and will be applied to the router itself. .. cfgcmd:: set zone-policy zone default-action [drop | reject] Change the default-action with this setting. .. cfgcmd:: set zone-policy zone description Set a meaningful description. Applying a Rule-Set to a Zone ============================= Before you are able to apply a rule-set to a zone you have to create the zones first. .. cfgcmd:: set zone-policy zone from firewall name .. cfgcmd:: set zone-policy zone from firewall ipv6-name You apply a rule-set always to a zone from an other zone, it is recommended to create one rule-set for each zone pair. .. code-block:: none set zone-policy zone DMZ from LAN firewall name LANv4-to-DMZv4 set zone-policy zone LAN from DMZ firewall name DMZv4-to-LANv4 *********************** Operation-mode Firewall *********************** Rule-set overview ================= .. opcmd:: show firewall This will show you a basic firewall overview .. code-block:: none vyos@vyos:~$ show firewall ------------------------ Firewall Global Settings ------------------------ Firewall state-policy for all IPv4 and Ipv6 traffic state action log ----- ------ --- invalid accept disabled established accept disabled related accept disabled ----------------------------- Rulesets Information ----------------------------- -------------------------------------------------------------------------- IPv4 Firewall "DMZv4-1-IN": Active on (eth0,IN) rule action proto packets bytes ---- ------ ----- ------- ----- 10 accept icmp 0 0 condition - saddr 10.1.0.0/24 daddr 0.0.0.0/0 LOG enabled 10000 drop all 0 0 condition - saddr 0.0.0.0/0 daddr 0.0.0.0/0 LOG enabled -------------------------------------------------------------------------- IPv4 Firewall "DMZv4-1-OUT": Active on (eth0,OUT) rule action proto packets bytes ---- ------ ----- ------- ----- 10 accept tcp_udp 1 60 condition - saddr 0.0.0.0/0 daddr 0.0.0.0/0 match-DST-PORT-GROUP DMZ-Ports /* DMZv4-1-OUT-10 */LOG enabled 11 accept icmp 1 84 condition - saddr 0.0.0.0/0 daddr 0.0.0.0/0 /* DMZv4-1-OUT-11 */LOG enabled 10000 drop all 6 360 condition - saddr 0.0.0.0/0 daddr 0.0.0.0/0 LOG enabled -------------------------------------------------------------------------- IPv4 Firewall "LANv4-IN": Inactive - Not applied to any interfaces or zones. rule action proto packets bytes ---- ------ ----- ------- ----- 10 accept all 0 0 condition - saddr 0.0.0.0/0 daddr 0.0.0.0/0 /* LANv4-IN-10 */ 10000 drop all 0 0 condition - saddr 0.0.0.0/0 daddr 0.0.0.0/0 .. opcmd:: show firewall summary This will show you a summary of rule-sets and groups .. code-block:: none vyos@vyos:~$ show firewall summary ------------------------ Firewall Global Settings ------------------------ Firewall state-policy for all IPv4 and Ipv6 traffic state action log ----- ------ --- invalid accept disabled related accept disabled established accept disabled ------------------------ Firewall Rulesets ------------------------ IPv4 name: Rule-set name Description References ------------- ----------- ---------- DMZv4-1-OUT (eth0,OUT) DMZv4-1-IN (eth0,IN) ------------------------ Firewall Groups ------------------------ Port Groups: Group name Description References ---------- ----------- ---------- DMZ-Ports DMZv4-1-OUT-10-destination Network Groups: Group name Description References ---------- ----------- ---------- LANv4 LANv4-IN-10-source, DMZv4-1-OUT-10-source, DMZv4-1-OUT-11-source .. opcmd:: show firewall statistics This will show you a statistic of all rule-sets since the last boot. .. opcmd:: show firewall [name | ipv6name] rule <1-9999> This command will give an overview of a rule in a single rule-set .. opcmd:: show firewall group Overview of defined groups. You see the type, the members, and where the group is used. .. code-block:: none vyos@vyos:~$ show firewall group DMZ-Ports Name : DMZ-Ports Type : port References : none Members : 80 443 8080 8443 vyos@vyos:~$ show firewall group LANv4 Name : LANv4 Type : network References : LANv4-IN-10-source Members : 10.10.0.0/16 .. opcmd:: show firewall [name | ipv6name] This command will give an overview of a single rule-set. .. opcmd:: show firewall [name | ipv6name] statistics This will show you a rule-set statistic since the last boot. .. opcmd:: show firewall [name | ipv6name] rule <1-9999> This command will give an overview of a rule in a single rule-set. Zone-Policy Overview ==================== .. opcmd:: show zone-policy zone Use this command to get an overview of a zone. .. code-block:: none vyos@vyos:~$ show zone-policy zone DMZ ------------------- Name: DMZ Interfaces: eth0 eth1 From Zone: name firewall ---- -------- LAN DMZv4-1-OUT Show Firewall log ================= .. opcmd:: show log firewall [name | ipv6name] Show the logs of a specific Rule-Set. .. note:: At the moment it not possible to look at the whole firewall log with VyOS operational commands. All logs will save to ``/var/logs/messages``. For example: ``grep '10.10.0.10' /var/log/messages`` Example Partial Config ====================== .. code-block:: none firewall { all-ping enable broadcast-ping disable config-trap disable group { network-group BAD-NETWORKS { network 198.51.100.0/24 network 203.0.113.0/24 } network-group GOOD-NETWORKS { network 192.0.2.0/24 } port-group BAD-PORTS { port 65535 } } name FROM-INTERNET { default-action accept description "From the Internet" rule 10 { action accept description "Authorized Networks" protocol all source { group { network-group GOOD-NETWORKS } } } rule 11 { action drop description "Bad Networks" protocol all source { group { network-group BAD-NETWORKS } } } rule 30 { action drop description "BAD PORTS" destination { group { port-group BAD-PORTS } } log enable protocol all } } } interfaces { ethernet eth1 { address dhcp description OUTSIDE duplex auto firewall { in { name FROM-INTERNET } } } } .. _routing-mss-clamp: **************** TCP-MSS Clamping **************** As Internet wide PMTU discovery rarely works, we sometimes need to clamp our TCP MSS value to a specific value. This is a field in the TCP Options part of a SYN packet. By setting the MSS value, you are telling the remote side unequivocally 'do not try to send me packets bigger than this value'. Starting with VyOS 1.2 there is a firewall option to clamp your TCP MSS value for IPv4 and IPv6. .. note:: MSS value = MTU - 20 (IP header) - 20 (TCP header), resulting in 1452 bytes on a 1492 byte MTU. IPv4 ==== .. cfgcmd:: set firewall options interface adjust-mss Use this command to set the maximum segment size for IPv4 transit packets on a specific interface (500-1460 bytes). Example ------- Clamp outgoing MSS value in a TCP SYN packet to `1452` for `pppoe0` and `1372` for your WireGuard `wg02` tunnel. .. code-block:: none set firewall options interface pppoe0 adjust-mss '1452' set firewall options interface wg02 adjust-mss '1372' IPv6 ==== .. cfgcmd:: set firewall options interface adjust-mss6 Use this command to set the maximum segment size for IPv6 transit packets on a specific interface (1280-1492 bytes). .. _firewall:ipv6_example: Example ------- Clamp outgoing MSS value in a TCP SYN packet to `1280` for both `pppoe0` and `wg02` interface. .. code-block:: none set firewall options interface pppoe0 adjust-mss6 '1280' set firewall options interface wg02 adjust-mss6 '1280' .. hint:: When doing your byte calculations, you might find useful this `Visual packet size calculator `_.