[NETFILTER]: Add nf_conntrack subsystem.

The existing connection tracking subsystem in netfilter can only
handle ipv4.  There were basically two choices present to add
connection tracking support for ipv6.  We could either duplicate all
of the ipv4 connection tracking code into an ipv6 counterpart, or (the
choice taken by these patches) we could design a generic layer that
could handle both ipv4 and ipv6 and thus requiring only one sub-protocol
(TCP, UDP, etc.) connection tracking helper module to be written.

In fact nf_conntrack is capable of working with any layer 3
protocol.

The existing ipv4 specific conntrack code could also not deal
with the pecularities of doing connection tracking on ipv6,
which is also cured here.  For example, these issues include:

1) ICMPv6 handling, which is used for neighbour discovery in
   ipv6 thus some messages such as these should not participate
   in connection tracking since effectively they are like ARP
   messages

2) fragmentation must be handled differently in ipv6, because
   the simplistic "defrag, connection track and NAT, refrag"
   (which the existing ipv4 connection tracking does) approach simply
   isn't feasible in ipv6

3) ipv6 extension header parsing must occur at the correct spots
   before and after connection tracking decisions, and there were
   no provisions for this in the existing connection tracking
   design

4) ipv6 has no need for stateful NAT

The ipv4 specific conntrack layer is kept around, until all of
the ipv4 specific conntrack helpers are ported over to nf_conntrack
and it is feature complete.  Once that occurs, the old conntrack
stuff will get placed into the feature-removal-schedule and we will
fully kill it off 6 months later.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 8296b38bf2701f..a84f9221e5f02d 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -1,3 +1,6 @@
+menu "Core Netfilter Configuration"
+	depends on NET && NETFILTER
+
 config NETFILTER_NETLINK
        tristate "Netfilter netlink interface"
        help
@@ -22,3 +25,74 @@ config NETFILTER_NETLINK_LOG
 	  and is also scheduled to replace the old syslog-based ipt_LOG
 	  and ip6t_LOG modules.
 
+config NF_CONNTRACK
+	tristate "Layer 3 Independent Connection tracking (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && IP_NF_CONNTRACK=n
+	default n
+	---help---
+	  Connection tracking keeps a record of what packets have passed
+	  through your machine, in order to figure out how they are related
+	  into connections.
+
+	  Layer 3 independent connection tracking is experimental scheme
+	  which generalize ip_conntrack to support other layer 3 protocols.
+
+	  To compile it as a module, choose M here.  If unsure, say N.
+
+config NF_CT_ACCT
+	bool "Connection tracking flow accounting"
+	depends on NF_CONNTRACK
+	help
+	  If this option is enabled, the connection tracking code will
+	  keep per-flow packet and byte counters.
+
+	  Those counters can be used for flow-based accounting or the
+	  `connbytes' match.
+
+	  If unsure, say `N'.
+
+config NF_CONNTRACK_MARK
+	bool  'Connection mark tracking support'
+	depends on NF_CONNTRACK
+	help
+	  This option enables support for connection marks, used by the
+	  `CONNMARK' target and `connmark' match. Similar to the mark value
+	  of packets, but this mark value is kept in the conntrack session
+	  instead of the individual packets.
+
+config NF_CONNTRACK_EVENTS
+	bool "Connection tracking events"
+	depends on NF_CONNTRACK
+	help
+	  If this option is enabled, the connection tracking code will
+	  provide a notifier chain that can be used by other kernel code
+	  to get notified aboutchanges in the connection tracking state.
+
+	  If unsure, say `N'.
+
+config NF_CT_PROTO_SCTP
+	tristate 'SCTP protocol on new connection tracking support (EXPERIMENTAL)'
+	depends on EXPERIMENTAL && NF_CONNTRACK
+	default n
+	help
+	  With this option enabled, the layer 3 independent connection
+	  tracking code will be able to do state tracking on SCTP connections.
+
+	  If you want to compile it as a module, say M here and read
+	  Documentation/modules.txt.  If unsure, say `N'.
+
+config NF_CONNTRACK_FTP
+	tristate "FTP support on new connection tracking (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && NF_CONNTRACK
+	help
+	  Tracking FTP connections is problematic: special helpers are
+	  required for tracking them, and doing masquerading and other forms
+	  of Network Address Translation on them.
+
+	  This is FTP support on Layer 3 independent connection tracking.
+	  Layer 3 independent connection tracking is experimental scheme
+	  which generalize ip_conntrack to support other layer 3 protocols.
+
+	  To compile it as a module, choose M here.  If unsure, say N.
+
+endmenu