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Firewall mangle rules consist of five predefined chains that cannot be deleted:
- 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: |
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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
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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:
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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: |
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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].
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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. |
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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 |
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. |
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For example, if a router receives an IPsec encapsulated Gre packet, then rule | |
| 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. |
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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.
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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.
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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 (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
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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: |
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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 |
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| 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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