Common Firewall Matchers and Actions
Common Actions and Associated properties
| Property | Description |
|---|---|
| action (action name; Default: accept) | Action to take if a packet is matched by the rule: accept - accept the packet. A packet is not passed to the next firewall rule. add-dst-to-address-list - add destination address to address list specified by address-list parameter add-src-to-address-list - add source address to address list specified by address-list parameter jump - jump to the user-defined chain specified by the value of jump-target parameter log - add a message to the system log containing the following data: in-interface, out-interface, src-mac, protocol, src-ip:port->dst-ip:port and length of the packet. After a packet is matched it is passed to the next rule in the list, similar to passthrough passthrough - if a packet is matched by the rule, increase the counter and go to the next rule (useful for statistics) return - passes control back to the chain from where the jump took place |
| address-list (name; Default: ) | Name of the address list to be used. Applicable if the action is add-dst-to-address-list or add-src-to-address-list |
| address-list-timeout (none-dynamic | none-static | time; Default: none-dynamic) | Time interval after which the address will be removed from the address list specified by the address-list parameter. Used in conjunction with add-dst-to-address-list or add-src-to-address-list actions. none-dynamic (00:00:00) will leave the address in the address list till reboot none-static will leave the address in the address list forever and will be included in the configuration export/backup |
| jump-target (name; Default: ) | Name of the target chain to jump to. Applicable only if action=jump |
| log(yes | no; Default: no) | Add a message to the system log containing the following data: in-interface, out-interface, src-mac, protocol, src-ip:port->dst-ip:port, and length of the packet. Allows logging of packets even if action is not "log", useful for debugging the firewall. |
| log-prefix (string; Default: ) | Adds the specified text at the beginning of every log message. Applicable if action=log or log=yes is configured. |
Stats
To view matching statistics by firewall rules, run the /ip/firewall/filter/print stats command or /ipv6/firewall/filter/print stats for IPv6 firewall.
| Property | Description |
|---|---|
| bytes (integer) | The total amount of bytes matched by the rule |
| packets (integer) | The total amount of packets matched by the rule |
[admin@MikroTik] > ip firewall filter print stats
Flags: X - disabled, I - invalid, D - dynamic
# CHAIN ACTION BYTES PACKETS
0 D ;;; special dummy rule to show fasttrack counters
forward passthrough 50 507 925 242 50 048 246
1 ;;; defconf: drop invalid
forward drop 432 270 9 719
2 ;;; defconf: drop invalid
input drop 125 943 2 434
3 input accept 20 090 211 549 20 009 864
4 ;;; defconf: accept ICMP
input accept 634 926 7 648
5 ;;; defconf: drop all not coming from LAN
input drop 4 288 079 83 428
6 ;;; defconf: accept in ipsec policy
forward accept 0 0
7 ;;; defconf: accept out ipsec policy
forward accept 0 0
8 ;;; defconf: fasttrack
forward fasttrack-connection 28 505 528 775 31 504 682
9 ;;; defconf: accept established,related, untracked
forward accept 28 505 528 775 31 504 682
10 ;;; defconf: drop all from WAN not DSTNATed
forward drop 0 0
Statistics parameters can be reset by the following commands:
| Command | Description |
|---|---|
| reset-counters (id) | Reset statistics counters for a specific firewall rule or a list of rules. |
| reset-counters-all | Reset statistics counters for all firewall rules in the table. |
Other Useful Commands
By default print is equivalent to print static and shows only static rules.
To also print dynamic rules, use print all.
Or to print only dynamic rules use print dynamic.
Matchers
Tables below show all the properties that can be used as matchers in the firewall rules.
Matchers are executed in a specific order.
For IPv4:
- Source MAC Address
- In/Out interfaces
- In/Out interface lists
- IP Range
- Address type
- Address list
- TTL
- DSCP
- Length
- TLS
- IPv4 Options
- Dst Port
- Src Port
- Any Port
- TCP Options
- TCP MSS
- ICMP Codes
- Ingress Priority
- Priority
- Packet Mark
- Realm (routing table)
- Hotspot
- Connection Mark
- Connection State
- Connection NAT State
- Connection Bytes
- Connection Limit
- Connection Rate
- Ipsec Policy
- Helper
- String (content)
- PSD
- Layer7
- Random
- Nth
- PCC
- Limit
- Dst Limit
- Log
For IPv6:
- Address type
- Address list
- Source MAC Address
- In/Out interfaces
- In/Out interface lists
- Hop Limit
- DSCP
- Length
- TLS
- IPv6 Header
- Dst Port
- Src Port
- Any Port
- TCP Options
- TCP MSS
- ICMPv6 Codes
- Ingress Priority
- Priority
- Packet Mark
- Connection Mark
- Connection State
- Connection NAT State
- Connection Bytes
- Connection Limit
- Connection Rate
- Ipsec Policy
- Helper
- Match String (content)
- Random
- Nth
- PCC
- Limit
- Dst Limit
- Log
Properties are split into two parts:
- stateless - properties do not require connection tracking to function and can be used in stateless RAW firewall matching.
- stateful - properties either require connection tracking to function or are available only in stateful firewall config.
Stateless Properties
| Property | Description |
|---|---|
| chain (name; Default: ) | Specifies to which chain rule will be added. If the input does not match the name of an already defined chain, a new chain will be created |
| comment (string; Default: ) | Descriptive comment for the rule |
| content (string; Default: ) | Matches packets that contain specified text |
| dscp (integer: 0..63; Default: ) | Matches DSCP IP header field. |
| dst-address (IP/netmask | IP range; Default: ) | Matches packets whose destination is equal to the specified IP or falls into the specified IP range. |
| dst-address-list (name; Default: ) | Matches the destination address of a packet against a user-defined address-list. Supports only one list! |
| dst-address-type (unicast | local | broadcast | multicast ) | Matches destination address type: unicast - An IP address used for point-to-point transmission local - if dst-address is assigned to one of the router's interfaces broadcast - A packet is sent to all devices in a subnet multicast - packet is forwarded to a defined group of devices |
| dst-limit (integer[/time],integer,dst-address | dst-port | src-address[/time]; Default: ) | Matches packets until a given rate is exceeded. Rate is defined as packets per time interval. As opposed to the limit matcher, every flow has its own limit. Flow is defined by a mode parameter. Parameters are written in the following format: rate[/time],burst,mode[/expire]. rate - packet count per time interval per-flow to match time - specifies the time interval in which the packet count rate per flow cannot be exceeded (optional, 1s will be used if not specified) burst - initial number of packets per flow to match: this number gets recharged by one every time/rate, up to this number mode - this parameter specifies what unique fields define flow (src-address, dst-address, src-and-dst-address, dst-address-and-port, addresses-and-dst-port) expire - specifies interval after which flow with no packets will be allowed to be deleted (optional) |
| dst-port (integer[-integer]: 0..65535; Default: ) | List of destination port numbers or port number ranges |
| fragment (yes|no; Default: ) | Matches fragmented packets. The first (starting) fragment does not count. If connection tracking is enabled there will be no fragments as the system automatically assembles every packet. IPv4 only. |
| header (Type[:Mode]; Mode=contains|exact; Type=hop|dst|route|frag|ah|esp|none|proto) | Matches IPv6 next-header. Two types of header matching are possible controlled by mode parameter: contains - soft matching, matches at least selected headers exact - matches exact set of selected headers. IPv6 only. |
| hop-limit (Mode:Value; Mode=equal | greater-than | less-than | not-equal; Value=0..255) | Matches hop limit field in the IPv6 header. IPv6 only. |
| hotspot (auth | from-client | http | local-dst | to-client; Default: ) | Matches packets received from HotSpot clients against various HotSpot matchers. auth - matches authenticated HotSpot client packets from-client - matches packets that are coming from the HotSpot client http - matches HTTP requests sent to the HotSpot server local-dst - matches packets that are destined to the HotSpot server to-client - matches packets that are sent to the HotSpot client IPv4 Only. |
| icmp-options (integer:integer; Default: ) | Matches ICMP type: code fields |
| in-bridge-port (name; Default: ) | Actual interface the packet has entered the router if the incoming interface is a bridge. Works only if use-ip-firewall is enabled in bridge settings. |
| in-bridge-port-list (name; Default: ) | Set of interfaces defined in interface list. Works the same as in-bridge-port |
| in-interface (name; Default: ) | Interface the packet has entered the router |
| in-interface-list (name; Default: ) | Set of interfaces defined in interface list. Works the same as in-interface |
| ingress-priority (integer: 0..63; Default: ) | Matches the priority of an ingress packet. Priority may be derived from VLAN, WMM, DSCP, or MPLS EXP bit. read more |
| ipsec-policy (in | out, ipsec | none; Default: ) | Matches the policy used by IPsec. Value is written in the following format: direction, policy. The direction is used to select whether to match the policy used for decapsulation or the policy that will be used for encapsulation. in - valid in the PREROUTING, INPUT, and FORWARD chains out - valid in the POSTROUTING, OUTPUT, and FORWARD chains ipsec - matches if the packet is subject to IPsec processing none - matches packets that are not subject to IPsec processing (for example, IPSec transport packet). For example, if a router receives an IPsec encapsulated Gre packet, then rule ipsec-policy=in,ipsec will match Gre packet, but a rule ipsec-policy=in,none will match the ESP packet. |
| ipv4-options (any | loose-source-routing | no-record-route | no-router-alert | no-source-routing | no-timestamp | none | record-route | router-alert | strict-source-routing | timestamp; Default: ) | Matches IPv4 header options. any - matches packets with at least one of the IPv4 options loose-source-routing - match packets with a loose source routing option. This option is used to route the internet datagram based on information supplied by the source no-record-route - match packets with no record route option. This option is used to route the internet datagram based on information supplied by the source no-router-alert - match packets with no router alert option no-source-routing - match packets with no source routing option no-timestamp - match packets with no timestamp option record-route - match packets with record route option router-alert - match packets with router alert option strict-source-routing - match packets with a strict source routing option timestamp - match packets with a timestamp IPv4 only. |
| limit (integer,time,integer; Default: ) | Matches packets up to a limited rate (packet rate or bit rate). A rule using this matcher will match until this limit is reached. Parameters are written in the following format: rate[/time],burst:mode. rate - packet or bit count per time interval to match time - specifies the time interval in which the packet or bit rate cannot be exceeded (optional, 1s will be used if not specified) burst - initial number of packets or bits to match: this number gets recharged every 10ms so burst should be at least 1/100 of a rate per second mode - packet or bit mode |
| nth (integer,integer; Default: ) | Matches every nth packet: nth=2,1 rule will match every first packet of 2, hence, 50% of all the traffic that is matched by the rule |
| out-bridge-port (name; Default: ) | Actual interface the packet leaves the router if the outgoing interface is a bridge. Works only if use-ip-firewall is enabled in bridge settings. |
| out-bridge-port-list (name; Default: ) | Set of interfaces defined in interface list. Works the same as out-bridge-port |
| out-interface (; Default: ) | Interface the packet is leaving the router |
| out-interface-list (name; Default: ) | Set of interfaces defined in interface list. Works the same as out-interface |
| packet-mark (no-mark | string; Default: ) | Matches packets marked via mangle facility with particular packet mark. If no-mark is set, the rule will match any unmarked packet. |
| packet-size (integer[-integer]:0..65535; Default: ) | Matches packets of specified size or size range in bytes. |
| per-connection-classifier (ValuesToHash:Denominator/Remainder; Default: ) | PCC matcher (or Per Stream Classifier) allows dividing traffic into equal streams with the ability to keep packets with a specific set of options in one particular stream. Streams are hashed based on selected values to hash: both-addresses, both-addresses-and-ports, both-ports, dst-address, dst-address-and-port, dst-port, src-address, src-address-and-port, src-port. Read more >> |
| port (integer[-integer]: 0..65535; Default: ) | Matches if any (source or destination) port matches the specified list of ports or port ranges. Applicable only if protocol is TCP or UDP |
| priority (integer: 0..63; Default:) | Matches the packet's priority after a new priority has been set. Priority may be derived from VLAN, WMM, DSCP, MPLS EXP bit, or from the priority that has been set using the set-priority action. Read more |
| protocol (name or protocol ID; Default: tcp) | Matches particular IP protocol specified by protocol name or number |
| psd (integer,time,integer,integer; Default: ) | Attempts to detect TCP and UDP scans. Parameters are in the following format WeightThreshold, DelayThreshold, LowPortWeight, HighPortWeight. WeightThreshold - total weight of the latest TCP/UDP packets with different destination ports coming from the same host to be treated as port scan sequence DelayThreshold - delay for the packets with different destination ports coming from the same host to be treated as possible port scan subsequence LowPortWeight - the weight of the packets with privileged (<1024) destination port HighPortWeight - the weight of the packets with a non-privileged destination port IPv4 only. |
| random (integer: 1..99; Default: ) | Matches packets randomly with a given probability |
| src-address (Ip/Netmask, Ip range; Default: ) | Matches packets whose source is equal to a specified IP or falls into a specified IP range |
| src-address-list (name; Default: ) | Matches the source address of a packet against a user-defined address list. Supports only one list! |
| src-address-type (unicast | local | broadcast | multicast | blackhole | prohibit | unreachable ; Default: ) | Matches source address type: unicast - IP address used for point to point transmission local - if an address is assigned to one of the router's interfaces broadcast - packet is sent to all devices in the subnet multicast - packet is forwarded to a defined group of devices |
| src-port (integer[-integer]: 0..65535; Default: ) | List of source ports and ranges of source ports. Applicable only if a protocol is TCP or UDP |
| src-mac-address (MAC address; Default: ) | Matches the source MAC address of the packet |
| tcp-flags (ack | cwr | ece | fin | psh | rst | syn | urg; Default: ) | Matches specified TCP flags: ack - acknowledging data cwr - congestion window reduced ece - ECN-echo flag (explicit congestion notification) fin - close connection psh - push function rst - drop connection syn - new connection urg - urgent data |
| tcp-mss (integer[-integer]: 0..65535; Default: ) | Matches TCP MSS value of an IP packet |
| time (time-time,sat | fri | thu | wed | tue | mon | sun; Default: ) | Allows creating a filter based on the packets' arrival time and date or, for locally generated packets, departure time and date. The matcher takes into account the time and timezone configured on the router. |
| tls-host (string; Default: ) | Allows matching HTTPS traffic based on TLS SNI hostname. Accepts GLOB syntax for wildcard matching. Note that the matcher will not be able to match the hostname if the TLS handshake frame is fragmented into multiple TCP segments (packets). Watch our video about this value. |
| ttl (integer: 0..255; Default: ) | Matches packets TTL value. IPv4 Only. |
Stateful Properties
| Property | Description |
|---|---|
| connection-bytes (integer-integer; Default: ) | Matches packets only if a given amount of bytes has been transferred through the particular connection. 0 - means infinity, for example connection-bytes=2000000-0 means that the rule matches if more than 2MB has been transferred through the relevant connection |
| connection-limit (integer,netmask; Default: ) | Matches connections per address or address block after a given value is reached. Should be used together with connection-state=new and/or with tcp-flags=syn because the matcher is very resource-intensive |
| connection-mark (no-mark | string; Default: ) | Matches packets marked via mangle facility with a particular connection mark. If no-mark is set, the rule will match any unmarked connection |
| connection-nat-state (srcnat | dstnat; Default: ) | Can match connections that are srcnatted, dstnatted, or both. Note that connection-state=related connections' connection-nat-state is determined by the direction of the first packet. and if connection tracking needs to use dst-nat to deliver this connection to the same hosts as the main connection, it will be in connection-nat-state=dstnat even if there are no dst-nat rules at all |
| connection-rate (Integer 0..4294967295; Default: ) | Connection Rate is a firewall matcher that allows capturing traffic based on the present speed of the connection |
| connection-state (established | invalid | new | related | untracked; Default: ) | Interprets the connection tracking analytics data for a particular packet: established - a packet that belongs to an existing connection invalid - a packet that does not have a determined state in connection tracking (usually severe out-of-order packets, packets with wrong sequence/ack number, or in case of resource over usage on the router). An invalid packet will not participate in NAT (as only connection-state=new packets do), and will still contain the original source IP address when routed. We strongly suggest dropping all connection-state=invalid packets in the firewall filter forward and input chains new - the packet has started a new connection or is otherwise associated with a connection that has not seen packets in both directions related - a packet that is related to, but not part of an existing connection, such as ICMP errors or a packet that begins an FTP data connection untracked - a packet that was set to bypass connection tracking in firewall RAW tables. |
| connection-type (ftp | h323 | irc | pptp | quake3 | sip | tftp; Default: ) | Matches packets from related connections based on information from their connection tracking helpers. A relevant connection helper must be enabled under the: /ip/firewall/service-port |
| layer7-protocol (name; Default: ) | Layer7 filter name defined in the layer7 protocol menu. Read more>>. |
| p2p () | Matches some unencrypted P2P protocols. Deprecated in modern days since mostly everything is encrypted and requires deep packet inspection to identify. IPv4 only. |
| realm (integer: 0..4294967295; Default: ) | IPv4 only. |
| routing-mark (string; Default: ) | Matches packets marked by mangle facility with a particular routing mark |