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Firewall mangle rules consist of five predefined chains that cannot be deleted:
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- The PREROUTING chain: Rules in this chain apply to packets as they just arrive on the network interface;
- The INPUT chain: Rules in this chain apply to packets just before they’re given to a local process;
- The OUTPUT chain: The rules here apply to packets just after they’ve been produced by a process;
- The FORWARD chain: The rules here apply to any packets that are routed through the current host;
- The POSTROUTING chain: The rules in this chain apply to packets as they just leave the network interface;
Properties
Property | Description |
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action (action name; Default: accept) | Action to take if a packet is matched by the rule: |
accept 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 parameteradd-src-to-address-list - add source address to address list specified by address-list parameterchange-dscp - change the Differentiated Services Code Point (DSCP) field value specified by
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the - the
new-dscp parameter change-mss - change the Maximum Segment Size field value of the packet to a value specified
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by - by
the new-mss parameter change-
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ttl ttl - change the Time to Live field value of the packet to a value specified by
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the - the
new-ttl parameter clear-df - clear 'Do Not Fragment' Flagfasttrack-connection - shows fasttrack counters, useful for statisticsjump - jump to the user-defined chain specified by the value of jump-target parameterlog - 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 as passthrough mark-connection - place a mark specified by the new-connection-mark parameter on the entire connection that matches the rulemark-packet - place a mark specified by the new-packet-mark parameter on a packet that matches the rulemark-routing - place a mark specified by the new-routing-mark parameter on a packet. This kind of
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marks - mark is used for policy routing purposes only. Do not apply any other routing marks besides "main" for the packets processed by FastTrack, since FastTrack can only work in the main routing table.
passthrough - if a packet is matched by the rule, increase the counter and go to the next rule (useful for statistics).
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return return - pass control back to the chain from where the jump took place
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route route - forces packets to a specific gateway IP by ignoring normal routing
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decision - decisions (prerouting chain only)
set-priority - set priority specified by the new-priority parameter on the packets sent out through a link that is capable of transporting priority (VLAN or WMM-enabled wireless interface). Read moresniff-pc - send a packet to a remote RouterOS CALEA server.sniff-tzsp - send a packet to a remote TZSP compatible system (such as Wireshark). Set remote target with sniff-target and sniff-target-port parameters (Wireshark recommends port 37008)strip-ipv4-options - strip IPv4 option fields from IP header, the action does not actually remove IPv4 options but rather replaces all option octets with NOP, further matcher with ipv4-options=any will still match the packet.
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address-list (string; Default: ) | Name of the address list to be used. Applicable if 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 address-list parameter. Used in conjunction with add-dst-to-address-list or add-src-to-address-list actions
- Value of none-dynamic (
00:00:00 ) will leave the address in the address list till reboot - Value of none-static will leave the address in the address list forever and will be included in the configuration export/backup
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chain (name; Default: ) | Specifies to which chain the 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. |
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 (upload and download) 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 |
connection-mark (no-mark | string; Default: ) | Matches packets marked via mangle facility with 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 the capture of traffic based on the present speed of the connection. |
connection-state (established | invalid | new | related; Default: ) | Interprets the connection tracking analytics data for a particular packet:established - a packet that belongs to an existing connection
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invalid 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 a resource over usage on a router), for this reason, an invalid packet will not participate in NAT (as only connection-state=new packets do), and will still contain original source IP address when routed. We strongly suggest dropping all connection-state=invalid packets in the firewall filter forward and input chains
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new new - the packet has started a new connection, or is otherwise associated with a connection that has not seen packets in both directions
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related related - a packet that is related to, but not parts of an existing connection, such as ICMP errors or a packet that begins an FTP data connectionuntracked - packet which was set to bypass connection tracking in Firewall RAW tables.
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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: /ip firewall service-port |
content (string; Default: ) | Match packets that contain specified text |
dscp (integer: 0..63; Default: ) | Matches DSCP IP header field |
dst-address (IP/netmask | IP range; Default: ) | Matches packets where the destination is equal to the specified IP or falls into a specified IP range |
dst-address-list (name; Default: ) | Matches the destination address of a packet against a user-defined address list |
dst-address-type (unicast | local | broadcast | multicast; Default: ) | Matches destination address type: |
unicast unicast - IP address used for point to point transmission
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local local - if dst-address is assigned to one of the router's interfaces
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broadcast broadcast - packet is sent to all devices in a subnet
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multicast multicast - packet is forwarded to a defined group of devices
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dst-limit (integer[/time],integer,dst-address | dst-port | src-address[/time]; Default: ) | Matches packets until a given PPS limit is exceeded. As opposed to the limit matcher, every destination IP address/destination port has its own limit. Parameters are written in the following format: count[/time],burst,mode[/expire] .- count - maximum average packet rate measured in packets per
time interval - time - specifies the time interval in which the packet rate is measured (optional)
- burst - number of packets that are not counted by packet rate
- mode - the classifier for packet rate limiting
- expire - specifies interval after which recorded ip address /port will be deleted (optional)
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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 |
hotspot (auth | from-client | http | local-dst | to-client; Default: ) | Matches packets received from HotSpot clients against various HotSpot matches. |
auth auth - matches authenticated HotSpot client packetsfrom-client - matches packets that are coming from the HotSpot client
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http http - matches HTTP requests sent to the HotSpot serverlocal-dst - matches packets that are destined to the HotSpot serverto-client - matches packets that are sent to the HotSpot client
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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 |
in-interface (name; Default: ) | Interface the packet has entered the router |
ingress-priority (integer: 0..63; Default: ) | Matches ingress the priority of the packet. Priority may be derived from VLAN, WMM, or MPLS EXP bit. Read more |
ipsec-policy (in | out, ipsec | none; Default: ) | Matches the policy used by |
IpSecIPsec. 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 in - valid in the PREROUTING, INPUT, and FORWARD chains
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out out - valid in the POSTROUTING, OUTPUT, and FORWARD chains
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ipsec ipsec - matches if the packet is subject to
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IpSec none none - matches packet that is 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 any - match packet with at least one of the ipv4 optionsloose-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 sourceno-record-route - match packets with no record route option. This option is used to route the internet datagram based on information supplied by the sourceno-router-alert - match packets with no router alter optionno-source-routing - match packets with no source routing optionno-timestamp - match packets with no timestamp optionrecord-route - match packets with record route optionrouter-
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alert alert - match packets with router alter optionstrict-source-routing - match packets with strict source routing optiontimestamp - match packets with a timestamp
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jump-target (name; Default: ) | Name of the target chain to jump to. Applicable only if action=jump |
layer7-protocol (name; Default: ) | Layer7 filter name defined in layer7 protocol menu. |
limit (integer,time,integer; Default: ) | Matches packets until a given PPS limit is exceeded. Parameters are written in the following format: count[/time],burst .- count - maximum average packet rate measured in packets per
time interval - time - specifies the time interval in which the packet rate is measured (optional, 1s will be used if not specified)
- burst - number of packets that are not counted by packet rate
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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. |
log-prefix (string; Default: ) | Adds specified text at the beginning of every log message. Applicable if action=log or log=yes configured. |
new-dscp (integer: 0..63; Default: ) | Sets a new DSCP value for a packet |
new-mss (integer; Default: ) | Sets a new MSS for a packet. |
ClamptClamp-to-pmtu feature sets (DF) bit in the IP header to dynamically discover the PMTU of a path. Host sends all datagrams on that path with the DF bit set until receives ICMP
Destination Unreachable messages with a code meaning "fragmentation needed and DF set". Upon receipt of such a message, the source host reduces its assumed PMTU for the path. |
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new-packet-mark (string; Default: ) | Sets a new packet-mark value |
new-priority (integer | from-dscp | from-dscp-high-3-bits | from-ingress; Default: ) | Sets a new priority for a packet. This can be the VLAN, WMM, DSCP or MPLS EXP priority Read more. This property can also be used to set an internal priority. |
new-routing-mark (string; Default: |
)Sets a new routing-mark value) | Sets a new routing-mark value (in RouterOS v7 routing mark must be created before as a new Routing table) |
new-ttl (decrement | increment | set:integer; Default: ) | Sets a new Time to live value |
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 is leaving the router if the outgoing interface is a bridge |
out-interface (; Default: ) | Interface the packet is leaving the router |
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 |
passthrough (yes|no; Default: yes) | whether to let the packet to pass further (like action passthrough ) into the firewall or not (property only valid for some actions) |
per-connection-classifier (ValuesToHash:Denominator/Remainder; Default: ) | PCC matcher allows the division of traffic into equal streams with the ability to keep packets with a specific set of options in one particular stream |
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 |
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 packet with a non-privileged destination port
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random (integer: 1..99; Default: ) | Matches packets randomly with a given probability. |
routing-mark (string; Default: ) | Matches packets marked by mangle facility with particular routing mark |
route-dst (IP, Default:) | Matches packets with a specific gateway |
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 internal priority that has been set using the set-priority action |
src-address (IP/Netmask, IP range; Default: ) | Matches packets where the 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 |
src-address-type (unicast | local | broadcast | multicast; Default: ) | Matches source address type: |
unicast unicast - IP address used for point-to-point transmission
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local local - if an address is assigned to one of the router's interfaces
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broadcast broadcast - packet is sent to all devices in a subnet
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multicast multicast - packet is forwarded to a defined group of devices
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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 cwr cwr - congestion window reduced
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ece ece - ECN-echo flag (explicit congestion notification)
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fin psh rst syn urg |
tcp-mss (integer[-integer]: 0..65535; Default: ) | Matches the TCP MSS value of an IP packet |
time (time-time,sat | fri | thu | wed | tue | mon | sun; Default: ) | Allows creation of a filter based on the packets' arrival time and date or, for locally generated packets, departure time and date |
tls-host (string; Default: ) | Allows matching traffic based on TLS 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). |
ttl (equal | greater-than | less-than | not-equal : integer(0..255); Default: ) | Matches packets TTL value. |
Stats
To show additional read-only properties:
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It is a known fact that VPN links have a smaller packet size due to encapsulation overhead. A large packet with MSS that exceeds the MSS of the VPN link should be fragmented prior to before sending it via that kind of connection. However, if the packet has a Don't Fragment flag set, it cannot be fragmented and should be discarded. On links that have broken path MTU discovery (PMTUD), it may lead to a number of problems, including problems with FTP and HTTP data transfer and e-mail services.
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