Manual:IP/Firewall/Connection tracking

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Connection tracking entries

Sub-menu: /ip firewall connection

There are several ways to see what connections are making their way though the router.

In the Winbox Firewall window, you can switch to the Connections tab, to see current connections to/from/through your router. It looks like this:

2009-01-26 1346.jpg


All properties in connection list are read-only

Property Description
seen reply (yes | no)
assured (yes | no) "assured" flag indicates that this connection is assured and that it will not be erased if maximum possible tracked connection count is reached.
connection-mark (string) connection mark set by mangle rule.
connection-type (pptp | ftp | p2p) Type of connection, property is empty if connection tracking is unable to determine predefined connection type.
dst-address (ip[:port]) Destination address and port (if protocol is port based).
gre-key (integer)
gre-version (string)
icmp-code (string)
icmp-id (string)
icmp-type (string)
p2p (yes | no) Shows if connection is identified as p2p by firewall p2p matcher.
protocol (string) IP protocol type
reply-dst-address (ip[:port]) Destination address (and port) expected of return packets. Usually the same as "src-address:port"
reply-src-address (ip[:port]) Source address (and port) expected of return packets. Usually the same as "dst-address:port"
src-address (ip[:port]) Source address and port (if protocol is port based).
tcp-state (string) Current state of TCP connection :
  • "established"
  • "time-wait"
  • "close"
  • "syn-sent"
  • "syn-received"
timeout (time) Time after connection will be removed from connection list.

Connection tracking settings

Sub-menu: /ip firewall connection tracking


Property Description
enabled (yes | no; Default: yes) Allows to disable or enable connection tracking. Disabling connection tracking will cause several firewall features to stop working. See the list of affected features.
tcp-syn-sent-timeout (time; Default: 5s) TCP SYN timeout.
tcp-syn-received-timeout (time; Default: 5s) TCP SYN timeout.
tcp-established-timeout (time; Default: 1d) Time when established TCP connection times out.
tcp-fin-wait-timeout (time; Default: 10s)
tcp-close-wait-timeout (time; Default: 10s)
tcp-last-ack-timeout (time; Default: 10s)
tcp-time-wait-timeout (time; Default: 10s)
tcp-close-timeout (time; Default: 10s)
udp-timeout (time; Default: 10s)
udp-stream-timeout (time; Default: 3m)
icmp-timeout (time; Default: 10s)
generic-timeout (time; Default: 10m) Timeout for all other connection entries
tcp-syncookie (yes | no; Default: no)

Read-only properties

Property Description
max-entries (integer) Max amount of entries that connection tracking table can hold. This value depends on installed amount of RAM.
total-entries (integer) Amount of connections that currently connection table holds.

Features affected by connection tracking

  • NAT
  • firewall:
    • connection-bytes
    • connection-mark
    • connection-type
    • connection-state
    • connection-limit
    • connection-rate
    • layer7-protocol
    • p2p
    • new-connection-mark
    • tarpit
  • p2p matching in simple queues