# See also: http://conntrack-tools.netfilter.org/support.html

# 

# There are 3 different modes of running conntrackd: "alarm", "notrack" and "ftfw"

#

# The default package ships with a FTFW configuration, see /usr/share/doc/conntrackd*

# for example configurations for other modes.

#

# Synchronizer settings

#

Sync {

	Mode FTFW {

		#

		# Size of the resend queue (in objects). This is the maximum

		# number of objects that can be stored waiting to be confirmed

		# via acknoledgment. If you keep this value low, the daemon

		# will have less chances to recover state-changes under message

		# omission. On the other hand, if you keep this value high,

		# the daemon will consume more memory to store dead objects.

		# Default is 131072 objects.

		#

		# ResendQueueSize 131072

		#

		# This parameter allows you to set an initial fixed timeout

		# for the committed entries when this node goes from backup

		# to primary. This mechanism provides a way to purge entries

		# that were not recovered appropriately after the specified

		# fixed timeout. If you set a low value, TCP entries in

		# Established states with no traffic may hang. For example,

		# an SSH connection without KeepAlive enabled. If not set,

		# the daemon uses an approximate timeout value calculation

		# mechanism. By default, this option is not set.

		#

		# CommitTimeout 180

		#

		# If the firewall replica goes from primary to backup,

		# the conntrackd -t command is invoked in the script. 

		# This command schedules a flush of the table in N seconds.

		# This is useful to purge the connection tracking table of

		# zombie entries and avoid clashes with old entries if you

		# trigger several consecutive hand-overs. Default is 60 seconds.

		#

		# PurgeTimeout 60

		# Set the acknowledgement window size. If you decrease this

		# value, the number of acknowlegdments increases. More

		# acknowledgments means more overhead as conntrackd has to

		# handle more control messages. On the other hand, if you

		# increase this value, the resend queue gets more populated.

		# This results in more overhead in the queue releasing.

		# The following value is based on some practical experiments

		# measuring the cycles spent by the acknowledgment handling

		# with oprofile. If not set, default window size is 300.

		#

		# ACKWindowSize 300

		#

		# This clause allows you to disable the external cache. Thus,

		# the state entries are directly injected into the kernel

		# conntrack table. As a result, you save memory in user-space

		# but you consume slots in the kernel conntrack table for

		# backup state entries. Moreover, disabling the external cache

		# means more CPU consumption. You need a Linux kernel

		# >= 2.6.29 to use this feature. By default, this clause is

		# set off. If you are installing conntrackd for first time,

		# please read the user manual and I encourage you to consider

		# using the fail-over scripts instead of enabling this option!

		#

		# DisableExternalCache Off

	}

	#

	# Multicast IP and interface where messages are

	# broadcasted (dedicated link). IMPORTANT: Make sure

	# that iptables accepts traffic for destination

	# 225.0.0.50, eg:

	#

	#	iptables -I INPUT -d 225.0.0.50 -j ACCEPT

	#	iptables -I OUTPUT -d 225.0.0.50 -j ACCEPT

	#

	Multicast {

		# 

		# Multicast address: The address that you use as destination

		# in the synchronization messages. You do not have to add

		# this IP to any of your existing interfaces. If any doubt,

		# do not modify this value.

		#

		IPv4_address 225.0.0.50

		#

		# The multicast group that identifies the cluster. If any

		# doubt, do not modify this value.

		#

		Group 3780

		#

		# IP address of the interface that you are going to use to

		# send the synchronization messages. Remember that you must

		# use a dedicated link for the synchronization messages.

		#

		IPv4_interface 192.168.100.100

		#

		# The name of the interface that you are going to use to

		# send the synchronization messages.

		#

		Interface eth2

		# The multicast sender uses a buffer to enqueue the packets

		# that are going to be transmitted. The default size of this

		# socket buffer is available at /proc/sys/net/core/wmem_default.

		# This value determines the chances to have an overrun in the

		# sender queue. The overrun results packet loss, thus, losing

		# state information that would have to be retransmitted. If you

		# notice some packet loss, you may want to increase the size

		# of the sender buffer. The default size is usually around

		# ~100 KBytes which is fairly small for busy firewalls.

		#

		SndSocketBuffer 1249280

		# The multicast receiver uses a buffer to enqueue the packets

		# that the socket is pending to handle. The default size of this

		# socket buffer is available at /proc/sys/net/core/rmem_default.

		# This value determines the chances to have an overrun in the

		# receiver queue. The overrun results packet loss, thus, losing

		# state information that would have to be retransmitted. If you

		# notice some packet loss, you may want to increase the size of

		# the receiver buffer. The default size is usually around

		# ~100 KBytes which is fairly small for busy firewalls.

		#

		RcvSocketBuffer 1249280

		# 

		# Enable/Disable message checksumming. This is a good

		# property to achieve fault-tolerance. In case of doubt, do

		# not modify this value.

		#

		Checksum on

	}

	#

	# You can specify more than one dedicated link. Thus, if one dedicated

	# link fails, conntrackd can fail-over to another. Note that adding

	# more than one dedicated link does not mean that state-updates will

	# be sent to all of them. There is only one active dedicated link at

	# a given moment. The `Default' keyword indicates that this interface

	# will be selected as the initial dedicated link. You can have 

	# up to 4 redundant dedicated links. Note: Use different multicast 

	# groups for every redundant link.

	#

	# Multicast Default {

	#	IPv4_address 225.0.0.51

	#	Group 3781

	#	IPv4_interface 192.168.100.101

	#	Interface eth3

	#	# SndSocketBuffer 1249280

	#	# RcvSocketBuffer 1249280

	#	Checksum on

	# }

	#

	# You can use Unicast UDP instead of Multicast to propagate events.

	# Note that you cannot use unicast UDP and Multicast at the same

	# time, you can only select one.

	# 

	# UDP {

		# 

		# UDP address that this firewall uses to listen to events.

		#

		# IPv4_address 192.168.2.100

		#

		# or you may want to use an IPv6 address:

		#

		# IPv6_address fe80::215:58ff:fe28:5a27

		#

		# Destination UDP address that receives events, ie. the other

		# firewall's dedicated link address.

		#

		# IPv4_Destination_Address 192.168.2.101

		#

		# or you may want to use an IPv6 address:

		#

		# IPv6_Destination_Address fe80::2d0:59ff:fe2a:775c

		#

		# UDP port used

		#

		# Port 3780

		#

		# The name of the interface that you are going to use to

		# send the synchronization messages.

		#

		# Interface eth2

		# 

		# The sender socket buffer size

		#

		# SndSocketBuffer 1249280

		#

		# The receiver socket buffer size

		#

		# RcvSocketBuffer 1249280

		# 

		# Enable/Disable message checksumming. 

		#

		# Checksum on

	# }

	# 

	# Other unsorted options that are related to the synchronization.

	# 

	# Options {

		#

		# TCP state-entries have window tracking disabled by default,

		# you can enable it with this option. As said, default is off.

		# This feature requires a Linux kernel >= 2.6.36.

		#

		# TCPWindowTracking Off

	# }

}

#

# General settings

#

General {

	#

	# Set the nice value of the daemon, this value goes from -20

	# (most favorable scheduling) to 19 (least favorable). Using a

	# very low value reduces the chances to lose state-change events.

	# Default is 0 but this example file sets it to most favourable

	# scheduling as this is generally a good idea. See man nice(1) for

	# more information.

	#

	Nice -20

	#

	# Select a different scheduler for the daemon, you can select between

	# RR and FIFO and the process priority (minimum is 0, maximum is 99).

	# See man sched_setscheduler(2) for more information. Using a RT

	# scheduler reduces the chances to overrun the Netlink buffer.

	#

	# Scheduler {

	#	Type FIFO

	#	Priority 99

	# }

	#

	# Number of buckets in the cache hashtable. The bigger it is,

	# the closer it gets to O(1) at the cost of consuming more memory.

	# Read some documents about tuning hashtables for further reference.

	#

	HashSize 32768

	#

	# Maximum number of conntracks, it should be double of: 

	# $ cat /proc/sys/net/netfilter/nf_conntrack_max

	# since the daemon may keep some dead entries cached for possible

	# retransmission during state synchronization.

	#

	HashLimit 131072

	#

	# Logfile: on (/var/log/conntrackd.log), off, or a filename

	# Default: off

	#

	LogFile on

	#

	# Syslog: on, off or a facility name (daemon (default) or local0..7)

	# Default: off

	#

	#Syslog on

	#

	# Lockfile

	# 

	LockFile /var/lock/conntrack.lock

	#

	# Unix socket configuration

	#

	UNIX {

		Path /var/run/conntrackd.ctl

		Backlog 20

	}

	#

	# Netlink event socket buffer size. If you do not specify this clause,

	# the default buffer size value in /proc/net/core/rmem_default is

	# used. This default value is usually around 100 Kbytes which is

	# fairly small for busy firewalls. This leads to event message dropping

	# and high CPU consumption. This example configuration file sets the

	# size to 2 MBytes to avoid this sort of problems.

	#

	NetlinkBufferSize 2097152

	#

	# The daemon doubles the size of the netlink event socket buffer size

	# if it detects netlink event message dropping. This clause sets the

	# maximum buffer size growth that can be reached. This example file

	# sets the size to 8 MBytes.

	#

	NetlinkBufferSizeMaxGrowth 8388608

	#

	# If the daemon detects that Netlink is dropping state-change events,

	# it automatically schedules a resynchronization against the Kernel

	# after 30 seconds (default value). Resynchronizations are expensive

	# in terms of CPU consumption since the daemon has to get the full

	# kernel state-table and purge state-entries that do not exist anymore.

	# Be careful of setting a very small value here. You have the following

	# choices: On (enabled, use default 30 seconds value), Off (disabled)

	# or Value (in seconds, to set a specific amount of time). If not

	# specified, the daemon assumes that this option is enabled.

	#

	# NetlinkOverrunResync On

	#

	# If you want reliable event reporting over Netlink, set on this

	# option. If you set on this clause, it is a good idea to set off

	# NetlinkOverrunResync. This option is off by default and you need

	# a Linux kernel >= 2.6.31.

	#

	# NetlinkEventsReliable Off

	# 

	# By default, the daemon receives state updates following an

	# event-driven model. You can modify this behaviour by switching to

	# polling mode with the PollSecs clause. This clause tells conntrackd

	# to dump the states in the kernel every N seconds. With regards to

	# synchronization mode, the polling mode can only guarantee that

	# long-lifetime states are recovered. The main advantage of this method

	# is the reduction in the state replication at the cost of reducing the

	# chances of recovering connections.

	#

	# PollSecs 15

	#

	# The daemon prioritizes the handling of state-change events coming

	# from the core. With this clause, you can set the maximum number of

	# state-change events (those coming from kernel-space) that the daemon

	# will handle after which it will handle other events coming from the

	# network or userspace. A low value improves interactivity (in terms of

	# real-time behaviour) at the cost of extra CPU consumption.

	# Default (if not set) is 100.

	#

	# EventIterationLimit 100

	#

	# Event filtering: This clause allows you to filter certain traffic,

	# There are currently three filter-sets: Protocol, Address and

	# State. The filter is attached to an action that can be: Accept or

	# Ignore. Thus, you can define the event filtering policy of the

	# filter-sets in positive or negative logic depending on your needs.

	# You can select if conntrackd filters the event messages from 

	# user-space or kernel-space. The kernel-space event filtering

	# saves some CPU cycles by avoiding the copy of the event message

	# from kernel-space to user-space. The kernel-space event filtering

	# is prefered, however, you require a Linux kernel >= 2.6.29 to

	# filter from kernel-space. If you want to select kernel-space 

	# event filtering, use the keyword 'Kernelspace' instead of 

	# 'Userspace'.

	#

	Filter From Userspace {

		#

		# Accept only certain protocols: You may want to replicate

		# the state of flows depending on their layer 4 protocol.

		#

		Protocol Accept {

			TCP

			SCTP

			DCCP

			# UDP

			# ICMP # This requires a Linux kernel >= 2.6.31

			# IPv6-ICMP # This requires a Linux kernel >= 2.6.31

		}

		#

		# Ignore traffic for a certain set of IP's: Usually all the

		# IP assigned to the firewall since local traffic must be

		# ignored, only forwarded connections are worth to replicate.

		# Note that these values depends on the local IPs that are

		# assigned to the firewall.

		#

		Address Ignore {

			IPv4_address 127.0.0.1 # loopback

			IPv4_address 192.168.0.100 # virtual IP 1

			IPv4_address 192.168.1.100 # virtual IP 2

			IPv4_address 192.168.0.1

			IPv4_address 192.168.1.1

			IPv4_address 192.168.100.100 # dedicated link ip

			#

			# You can also specify networks in format IP/cidr.

			# IPv4_address 192.168.0.0/24

			#

			# You can also specify an IPv6 address

			# IPv6_address ::1

		}

		#

		# Uncomment this line below if you want to filter by flow state.

		# This option introduces a trade-off in the replication: it

		# reduces CPU consumption at the cost of having lazy backup 

		# firewall replicas. The existing TCP states are: SYN_SENT,

		# SYN_RECV, ESTABLISHED, FIN_WAIT, CLOSE_WAIT, LAST_ACK,

		# TIME_WAIT, CLOSED, LISTEN.

		#

		# State Accept {

		#	ESTABLISHED CLOSED TIME_WAIT CLOSE_WAIT for TCP

		# }

	}

}