View source for Manual:IP/Firewall/Mangle

{{Versions|v3, v4, v5, v6+}}

<div class=manual>

==Summary==
<p id="shbox"><b>Sub-menu:</b> <code>/ip firewall mangle</code></p>
<br />

<p>
Mangle is a kind of 'marker' that marks packets for future processing with special marks. Many other facilities in RouterOS make use of these marks, e.g. queue trees, NAT, routing. They identify a packet based on its mark and process it accordingly. The mangle marks exist only within the router, they are not transmitted across the network.
</p>
<p>
Additionally, the mangle facility is used to modify some fields in the IP header, like TOS (DSCP) and TTL fields.
</p>


==Properties==

<table class="styled_table">
<tr>
   <th width="40%">Property</th>
   <th >Description</th>
</tr>
<tr>
    <td><var><b>action</b></var> (<em>action name</em>; Default: <b>accept</b>)</td>
    <td>Action to take if packet is matched by the rule: 
<ul class="bullets">
<li> <var>accept</var> - accept the packet. Packet is not passed to next firewall rule.
<li> <var>add-dst-to-address-list</var> - add destination address to [[Address list]] specified by <code>address-list</code> parameter
<li> <var>add-src-to-address-list</var> - add source address to [[Address list]] specified by <code>address-list</code> parameter
<li> <var>change-dscp</var> - change Differentiated Services Code Point (DSCP) field value specified by the new-dscp parameter
<li> <var>change-mss</var> - change Maximum Segment Size field value of the packet to a value specified by the new-mss parameter 
<li> <var>change-ttl</var> - change Time to Live field value of the packet to a value specified by the new-ttl parameter
<li> <var>clear-df</var> - clear 'Do Not Fragment' Flag
<li> <var>jump</var> - jump to the user defined chain specified by the value of <code>jump-target</code> parameter
<li> <var>log</var> - add a message to the system log containing following data: in-interface, out-interface, src-mac, protocol, src-ip:port->dst-ip:port and length of the packet. After packet is matched it is passed to next rule in the list, similar as <code>passthrough</code>
<li> <var>mark-connection</var> - place a mark specified by the new-connection-mark parameter on the entire connection that matches the rule 
<li> <var>mark-packet</var> - place a mark specified by the new-packet-mark parameter on a packet that matches the rule 
<li> <var>mark-routing</var> - place a mark specified by the new-routing-mark parameter on a packet. This kind of marks is used for policy routing purposes only 
<li> <var>passthrough</var> - ignore this rule and go to next one (useful for statistics).
<li> <var>return</var> - pass control back to the chain from where the jump took place 
<li> <var>set-priority</var> - 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). [[WMM#How_to_set_priority | Read more>]]
<li> <var>sniff-pc</var>
<li> <var>sniff-tzsp</var> - send packet to a remote TZSP compatible system (such as Wireshark). Set remote target with <code>sniff-target</code> and <code>sniff-target-port</code> parameters (Wireshark recommends port 37008)
<li> <var>strip-ipv4-options</var> - strip IPv4 option fields from IP header.
</ul>
</td>
</tr>
<tr>
    <td><var><b>address-list</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td>Name of the address list to be used. Applicable if action is <code>add-dst-to-address-list</code> or <code>add-src-to-address-list</code> </td>
</tr>
<tr>
    <td><var><b>address-list-timeout</b></var> (<em>time</em>; Default: <b>00:00:00</b>)</td>
    <td>Time interval after which the address will be removed from the address list specified by <code>address-list</code> parameter. Used in conjunction with <code>add-dst-to-address-list</code> or <code>add-src-to-address-list</code> actions<br />
Value of <code>00:00:00</code> will leave the address in the address list forever</td>
</tr>
<tr>
    <td><var><b>chain</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>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. </td>
</tr>
<tr>
    <td><var><b>comment</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td>Descriptive comment for the rule.</td>
</tr>
<tr>
    <td><var><b>connection-bytes</b></var> (<em>integer-integer</em>; Default: <b></b>)</td>
    <td>Matches packets only if a given amount of bytes has been transfered through the particular connection. 0 - means infinity, for example <code>connection-bytes=2000000-0</code> means that the rule matches if more than 2MB has been transfered through the relevant connection </td>
</tr>
<tr>
    <td><var><b>connection-limit</b></var> (<em>integer,netmask</em>; Default: <b></b>)</td>
    <td>Restrict connection limit per address or address block</td>
</tr>
<tr>
    <td><var><b>connection-mark</b></var> (<em>no-mark | string</em>; Default: <b></b>)</td>
    <td>Matches packets marked via mangle facility with particular connection mark. If <b>no-mark</b> is set, rule will match any unmarked connection.</td>
</tr>
<tr>
    <td><var><b>connection-rate</b></var> (<em>Integer 0..4294967295</em>; Default: <b></b>)</td>
    <td>Connection Rate is a firewall matcher that allows the capture of traffic based on the present speed of the connection. <code>[[Connection_Rate | Read more >>]]</code></td>
</tr>
<tr>
    <td><var><b>connection-state</b></var> (<em>estabilished | invalid | new | related</em>; Default: <b></b>)</td>
    <td>Interprets the connection tracking analysis data for a particular packet:
<ul class="bullets">
<li> <var>established</var> - a packet which belongs to an existing connection
<li> <var>invalid</var> - a packet which could not be identified for some reason
<li> <var>new</var> - the packet has started a new connection, or otherwise
associated with a connection which has not seen packets in both directions
<li> <var>related</var> - a packet which is related to, but not part of an existing connection, such as ICMP errors or a packet which begins FTP data connection 
</ul>
</td>
</tr>
<tr>
    <td><var><b>connection-type</b></var> (<em>ftp | h323 | irc | pptp | quake3 | sip | tftp</em>; Default: <b></b>)</td>
    <td>Matches packets from related connections based on information from their connection tracking helpers. A relevant connection helper must be enabled under [[IP/Services | /ip firewall service-port]]</td>
</tr>
<tr>
    <td><var><b>content</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td>Match packets that contain specified text</td>
</tr>
<tr>
    <td><var><b>dscp</b></var> (<em>integer: 0..63</em>; Default: <b></b>)</td>
    <td>Matches DSCP IP header field.</td>
</tr>
<tr>
    <td><var><b>dst-address</b></var> (<em>IP/netmask | IP range</em>; Default: <b></b>)</td>
    <td>Matches packets where destination is equal to specified IP or falls into specified IP range.</td>
</tr>
<tr>
    <td><var><b>dst-address-list</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>Matches destination address of a packet against user-defined [[Address_list | address list]]</td>
</tr>
<tr>
    <td><var><b>dst-address-type</b></var> (<em>unicast | local | broadcast | multicast</em>; Default: <b></b>)</td>
    <td>Matches destination address type:
<ul class="bullets">
<li> <var>unicast</var> - IP address used for point to point transmission
<li> <var>local</var> - if dst-address is assigned to one of router's interfaces
<li> <var>broadcast</var> - packet is sent to all devices in subnet
<li> <var>multicast</var> - packet is forwarded to defined group of devices
</ul>
</td>
</tr>
<tr>
    <td><var><b>dst-limit</b></var> (<em>integer[/time],integer,dst-address | dst-port | src-address[/time]</em>; Default: <b></b>)</td>
    <td>Matches packets until a given pps limit is exceeded. As opposed to the <var>limit</var> matcher, every destination IP address / destination port has it's own limit. Parameters are written in following format: <code>count[/time],burst,mode[/expire]</code>.
<ul class="bullets">
<li><b>count</b> - maximum average packet rate measured in packets per <code>time</code> interval
<li><b>time</b> - specifies the time interval in which the packet rate is measured (optional)
<li><b>burst</b> - number of packets which are not counted by packet rate
<li><b>mode</b> - the classifier for packet rate limiting
<li><b>expire</b> - specifies interval after which recored ip address /port will be deleted (optional)
</ul>
</td>
</tr>
<tr>
    <td><var><b>dst-port</b></var> (<em>integer[-integer]: 0..65535</em>; Default: <b></b>)</td>
    <td>List of destination port numbers or port number ranges</td>
</tr>
<tr>
    <td><var><b>fragment</b></var> (<em>yes|no</em>; Default: <b></b>)</td>
    <td>Matches fragmented packets. First (starting) fragment does not count. If connection tracking is enabled there will be no fragments as system automatically assembles every packet</td>
</tr>
<tr>
    <td><var><b>hotspot</b></var> (<em>auth | from-client | http | local-dst | to-client</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>icmp-options</b></var> (<em>integer:integer</em>; Default: <b></b>)</td>
    <td>Matches ICMP "type:code" fields</td>
</tr>
<tr>
    <td><var><b>in-bridge-port</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>Actual interface the packet has entered the router, if incoming interface is bridge</td>
</tr>
<tr>
    <td><var><b>in-interface</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>Interface the packet has entered the router</td>
</tr>
<tr>
    <td><var><b>ingress-priority</b></var> (<em>integer: 0..63</em>; Default: <b></b>)</td>
    <td>Matches ingress priority of the packet. Priority may be derived from VLAN, WMM or MPLS EXP bit. <code>[[WMM | Read more >>]]</code></td>
</tr>

<tr>
    <td><var><b>ipsec-policy</b></var> (<em>in | out, ipsec | none</em>; Default: <b></b>)</td>
    <td>Matches the policy used by IpSec. Value is written in following format: <code><b>direction, policy</b></code>. Direction is Used to select whether to match the policy used for decapsulation or the policy that will be used for encapsulation.
            <ul>
            <li><var>in</var> - valid in the PREROUTING, INPUT and FORWARD chains</li>
            <li><var>out</var> - valid in the POSTROUTING, OUTPUT and FORWARD chains</li>
            </ul>
            <ul>
            <li><var>ipsec</var> - matches if the packet is subject to IPsec processing;</li>
            <li><var>none</var> - matches ipsec transport packet.</li>
            </ul>
            <p>For example, if router receives Ipsec encapsulated Gre packet, then rule <code>ipsec-policy=in,ipsec</code> will match Gre packet, but rule <code>ipsec-policy=in,none</code> will match ESP packet.</p></td>
</tr>
<tr>
    <td><var><b>ipv4-options</b></var> (<em>any | loose-source-routing | no-record-route | no-router-alert | no-source-routing | no-timestamp | none | record-route | router-alert | strict-source-routing | timestamp</em>; Default: <b></b>)</td>
    <td>Matches IPv4 header options.
<ul class="bullets">
<li> <var>any</var> - match packet with at least one of the ipv4 options 
<li> <var>loose-source-routing</var> - match packets with loose source routing option. This option is used to route the internet datagram based on information supplied by the source 
<li> <var>no-record-route</var> - match packets with no record route option. This option is used to route the internet datagram based on information supplied by the source 
<li> <var>no-router-alert</var> - match packets with no router alter option 
<li> <var>no-source-routing</var> - match packets with no source routing option 
<li> <var>no-timestamp</var> - match packets with no timestamp option 
<li> <var>record-route</var> - match packets with record route option 
<li> <var>router-alert</var> - match packets with router alter option 
<li> <var>strict-source-routing</var> - match packets with strict source routing option 
<li> <var>timestamp</var> - match packets with timestamp 
</ul>
</td>
</tr>
<tr>
    <td><var><b>jump-target</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>Name of the target chain to jump to. Applicable only if <code>action=jump</code></td>
</tr>
<tr>
    <td><var><b>layer7-protocol</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>Layer7 filter name defined in [[M:IP/Firewall/L7 | layer7 protocol menu]].</td>
</tr>
<tr>
    <td><var><b>limit</b></var> (<em>integer,time,integer</em>; Default: <b></b>)</td>
    <td>Matches packets until a given pps limit is exceeded. Parameters are written in following format: <code>count[/time],burst</code>.
<ul class="bullets">
<li><b>count</b> - maximum average packet rate measured in packets per <code>time</code> interval
<li><b>time</b> - specifies the time interval in which the packet rate is measured (optional, 1s will be used if not specified)
<li><b>burst</b> - number of packets which are not counted by packet rate
</ul>
</td>
</tr>
<tr>
    <td><var><b>log-prefix</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td>Adds specified text at the beginning of every log message. Applicable if <code>action=log</code></td>
</tr>
<tr>
    <td><var><b>new-connection-mark</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>new-dscp</b></var> (<em>integer: 0..63</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>new-mss</b></var> (<em>integer</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>new-packet-mark</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>new-priority</b></var> (<em>integer</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>new-routing-mark</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>new-ttl</b></var> (<em>decrement | increment | set:integer</em>; Default: <b></b>)</td>
    <td></td>
</tr>
<tr>
    <td><var><b>nth</b></var> (<em>integer,integer</em>; Default: <b></b>)</td>
    <td>Matches every nth packet. <code>[[NTH_in_RouterOS_3.x | Read more >>]]</code></td>
</tr>
<tr>
    <td><var><b>out-bridge-port</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>Actual interface the packet is leaving the router, if outgoing interface is bridge</td>
</tr>
<tr>
    <td><var><b>out-interface</b></var> (<em></em>; Default: <b></b>)</td>
    <td>Interface the packet is leaving the router</td>
</tr>
<tr>
    <td><var><b>p2p</b></var> (<em>all-p2p | bit-torrent | blubster | direct-connect | edonkey | fasttrack | gnutella | soulseek | warez | winmx</em>; Default: <b></b>)</td>
    <td>Matches packets from various peer-to-peer (P2P) protocols. Does not work on encrypted p2p packets.</td>
</tr>
<tr>
    <td><var><b>packet-mark</b></var> (<em>no-mark | string</em>; Default: <b></b>)</td>
    <td>Matches packets marked via mangle facility with particular packet mark. If <b>no-mark</b> is set, rule will match any unmarked packet.</td>
</tr>
<tr>
    <td><var><b>packet-size</b></var> (<em>integer[-integer]:0..65535</em>; Default: <b></b>)</td>
    <td>Matches packets of specified size or size range in bytes.</td>
</tr>
<tr>
    <td><var><b>per-connection-classifier</b></var> (<em>ValuesToHash:Denominator/Remainder</em>; Default: <b></b>)</td>
    <td>PCC matcher allows division of traffic into equal streams with ability to keep packets with specific set of options in one particular stream. <code>[[PCC | Read more >>]]</code></td>
</tr>
<tr>
    <td><var><b>port</b></var> (<em>integer[-integer]: 0..65535</em>; Default: <b></b>)</td>
    <td>Matches if any (source or destination) port matches the specified list of ports or port ranges. Applicable only if <code>protocol</code> is TCP or UDP</td>
</tr>
<tr>
    <td><var><b>protocol</b></var> (<em>name or protocol ID</em>; Default: <b>tcp</b>)</td>
    <td>Matches particular IP protocol specified by protocol name or number</td>
</tr>
<tr>
    <td><var><b>psd</b></var> (<em>integer,time,integer,integer</em>; Default: <b></b>)</td>
    <td>Attempts to detect TCP and UDP scans. Parameters are in following format <code>WeightThreshold, DelayThreshold, LopPortWeight, HighPortWeight</code>
<ul class="bullets">
<li> <b>WeightThreshold</b> - total weight of the latest TCP/UDP packets with different destination ports coming from the same host to be treated as port scan sequence 
<li> <b>DelayThreshold</b> - delay for the packets with different destination ports coming from the same host to be treated as possible port scan subsequence 
<li> <b>LowPortWeight</b> - weight of the packets with privileged (<=1024) destination port
<li> <b>HighPortWeight</b> - weight of the packet with non-priviliged destination port 
</ul>
</td>
</tr>
<tr>
    <td><var><b>random</b></var> (<em>integer: 1..99</em>; Default: <b></b>)</td>
    <td>Matches packets randomly with given probability.</td>
</tr>
<tr>
    <td><var><b>routing-mark</b></var> (<em>string</em>; Default: <b></b>)</td>
    <td>Matches packets marked by mangle facility with particular routing mark</td>
</tr>
<tr>
    <td><var><b>src-address</b></var> (<em>IP/Netmask, IP range</em>; Default: <b></b>)</td>
    <td>Matches packets where source is equal to specified IP or falls into specified IP range.</td>
</tr>
<tr>
    <td><var><b>src-address-list</b></var> (<em>name</em>; Default: <b></b>)</td>
    <td>Matches source address of a packet against user-defined [[Address_list | address list]]</td>
</tr>
<tr>
    <td><var><b>src-address-type</b></var> (<em>unicast | local | broadcast | multicast</em>; Default: <b></b>)</td>
    <td>
Matches source address type:
<ul class="bullets">
<li> <var>unicast</var> - IP address used for point to point transmission
<li> <var>local</var> - if address is assigned to one of router's interfaces
<li> <var>broadcast</var> - packet is sent to all devices in subnet
<li> <var>multicast</var> - packet is forwarded to defined group of devices
</ul>
</td>
</tr>
<tr>
    <td><var><b>src-port</b></var> (<em>integer[-integer]: 0..65535</em>; Default: <b></b>)</td>
    <td>List of source ports and ranges of source ports. Applicable only if protocol is TCP or UDP.</td>
</tr>
<tr>
    <td><var><b>src-mac-address</b></var> (<em>MAC address</em>; Default: <b></b>)</td>
    <td>Matches source MAC address of the packet</td>
</tr>
<tr>
    <td><var><b>tcp-flags</b></var> (<em>ack | cwr | ece | fin | psh | rst | syn | urg</em>; Default: <b></b>)</td>
    <td>Matches specified TCP flags
<ul class="bullets">
<li> <var>ack</var> - acknowledging data
<li> <var>cwr</var> - congestion window reduced 
<li> <var>ece</var> - ECN-echo flag (explicit congestion notification)
<li> <var>fin</var> - close connection
<li> <var>psh</var> - push function
<li> <var>rst</var> - drop connection
<li> <var>syn</var> - new connection
<li> <var>urg</var> - urgent data 
</ul>
</td>
</tr>
<tr>
    <td><var><b>tcp-mss</b></var> (<em>integer: 0..65535</em>; Default: <b></b>)</td>
    <td>Matches TCP MSS value of an IP packet</td>
</tr>
<tr>
    <td><var><b>time</b></var> (<em>time-time,sat | fri | thu | wed | tue | mon | sun</em>; Default: <b></b>)</td>
    <td>Allows creation of a filter based on the packets' arrival time and date or, for locally generated packets, departure time and date</td>
</tr>
<tr>
    <td><var><b>ttl</b></var> (<em>equal | greater-than | less-than | not-equal : integer(0..255)</em>; Default: <b></b>)</td>
    <td>Matches packets TTL value.</td>
</tr>
</table>

==Stats==
<p>
<code>/ip firewall filter print stats</code> will show additional read-only properties

<table class="styled_table">
<tr>
   <th width="40%">Property</th>
   <th >Description</th>
</tr>
<tr>
    <td><var><b>bytes</b></var> (<em>integer</em>)</td>
    <td>Total amount of bytes matched by the rule</td>
</tr>
<tr>
    <td><var><b>packets</b></var> (<em>integer</em>)</td>
    <td>Total amount of packets matched by the rule</td>
</tr>
</table>

<br />
By default <b>print</b> is equivalent to <b>print static</b> and shows only static rules. 
<pre>
[admin@dzeltenais_burkaans] /ip firewall mangle> print stats
Flags: X - disabled, I - invalid, D - dynamic 
 #   CHAIN              ACTION                  BYTES           PACKETS        
 0   prerouting         mark-routing            17478158        127631         
 1   prerouting         mark-routing            782505          4506           
</pre>
To print also dynamic rules use <b>print all</b>.
<pre>
[admin@dzeltenais_burkaans] /ip firewall mangle> print all stats
Flags: X - disabled, I - invalid, D - dynamic 
 #   CHAIN              ACTION                  BYTES           PACKETS        
 0   prerouting         mark-routing            17478158        127631         
 1   prerouting         mark-routing            782505          4506           
 2 D forward            change-mss              0               0              
 3 D forward            change-mss              0               0              
 4 D forward            change-mss              0               0              
 5 D forward            change-mss              129372          2031  
</pre>
Or to print only dynamic rules use <b>print dynamic</b>
<pre>
[admin@dzeltenais_burkaans] /ip firewall mangle> print stats dynamic 
Flags: X - disabled, I - invalid, D - dynamic 
 #   CHAIN              ACTION                  BYTES           PACKETS        
 0 D forward            change-mss              0               0              
 1 D forward            change-mss              0               0              
 2 D forward            change-mss              0               0              
 3 D forward            change-mss              132444          2079 
</pre>
<br />
</p>

==Menu specific commands==

<table class="styled_table">
<tr>
   <th width="40%">Property</th>
   <th >Description</th>
</tr>
<tr>
    <td><var><b>reset-counters</b></var> (<em>id</em>)</td>
    <td>Reset [[#Stats | statistics]] counters for specified firewall rules.</td>
</tr>
<tr>
    <td><var><b>reset-counters-all</b></var> (<em></em>)</td>
    <td>Reset [[#Stats | statistics]] counters for all firewall rules.</td>
</tr>
</table>

==Basic examples==

<h3>Change MSS</h3>
<p>
It is a well known fact that VPN links have smaller packet size due to incapsulation overhead. A large packet with MSS that exceeds the MSS of the VPN link should be fragmented prior to sending it via that kind of connection. However, if the packet has DF 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.
</p>

<p>
In case of link with broken PMTUD, a decrease of the MSS of the packets coming through the VPN link solves the problem. The following example demonstrates how to decrease the MSS value via mangle:

<pre>
/ip firewall mangle 
add out-interface=pppoe-out protocol=tcp tcp-flags=syn action=change-mss new-mss=1300 chain=forward
</pre>
</p>


<h3>Marking packets</h3>
<p>
Marking each packet is quite resource expensive especially if rule has to match against many parameters from IP header or address list containing hundreds of entries.
</p>
<p>
Lets say we want to 
* mark all <b>tcp</b> packets except tcp/80 and match these packets against <b>first</b> address list
* mark all <b>udp</b> packets and match them against <b>second</b> address list.
</p>

<pre>
/ip firewall mangle
  add chain=forward protocol=tcp port=!80 dst-address-list=first action=mark-packet new-packet-mark=first
  add chain=forward protocol=udp dst-address-list=second action=mark-packet new-packet-mark=second
</pre>

<p>
Setup looks quite simple and probably will work without problems in small networks.  Now multiply count of rules by 10, add few hundred entries in address list, run 100Mbit of traffic over this router and you will see how rapidly CPU usage is increasing. The reason for such behavior is that each rule reads IP header of every packet and tries to match collected data against parameters specified in firewall rule. 
</p>
<p>
Fortunately if connection tracking is enabled, we can use connection marks to optimize our setup.
</p>
<pre>
/ip firewall mangle
  add chain=forward protocol=tcp port=!80 dst-address-list=first connection-state=new action=mark-connection \ 
new-connection-mark=first
  add chain=forward connection-mark=first action=mark-packet new-packet-mark=first passthrough=no

  add chain=forward protocol=udp dst-address-list=second connection-state=new action=mark-connection \ 
new-connection-mark=second
  add chain=forward connection-mark=second action=mark-packet new-packet-mark=second passthrough=no
</pre>

Now first rule will try to match data from IP header only from first packet of new connection and add connection mark. Next rule will no longer check IP header for each packet, it will just compare connection marks resulting in lower CPU consumption. Additionally <code>passthrough=no</code> was added that helps to reduce CPU consumption even more.

</div>


{{Cont}}

[[Category:Manual|Firewallmangle]]
[[Category:Firewall|Firewallmangle]]