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This patch allows you to dump the internal and external expectation
cache in XML.
% conntrackd -i exp -x
<flow><layer3 protonum="2" protoname="ipv4"><expected><src>192.168.1.135</src><dst>130.89.148.12</dst></expected><mask><src>255.255.255.255</src><dst>255.255.255.255</dst></mask><master><src>192.168.1.135</src><dst>130.89.148.12</dst></master></layer3><layer4 protonum="6" protoname="tcp"><expected><sport>0</sport><dport>9082</dport></expected><mask><sport>0</sport><dport>65535</dport></mask><master><sport>50518</sport><dport>21</dport></master></layer4><meta><helper-name>ftp</helper-name></meta></flow>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds support to synchronize expectations between
firewalls. This addition aims to re-use as much as possible
of the existing infrastructure for stability reasons. The
expectation support has been tested with the FTP helper.
This extension requires libnetfilter_conntrack 1.0.0.
If this is the first time you're playing with conntrackd,
I *strongly* recommend you to get working setup of conntrackd
without expectation support before as described in the
documentation. Then, enabling expectation support is rather
easy.
To know more about expectations, if you're not familiar with them,
I suggest you to read:
"Netfilter's Connection Tracking System"
http://people.netfilter.org/pablo/docs/login.pdf
Reprinted from ;login: The Magazine of USENIX, vol. 31, no. 3
(Berkeley, CA: USENIX Association, 2006, pp40-45.)
In short, expectations allow one Linux firewall to filter multi-flow
traffic like FTP, SIP and H.323.
In my testbed, there are two firewalls in a primary-backup configuration
running keepalived. The use a couple of floating cluster IP address
(192.168.0.100 and 192.168.1.100) that are used by the client. These
firewalls protect one FTP server (192.168.1.2) that will be accessed by
one client.
In ASCII art, it looks like this:
192.168.0.100 192.168.1.100
eth1 eth2
fw-1
/ \ FTP
-- client ------ ------ server --
192.168.0.2 \ / 192.168.1.2
fw-2
This is the rule-set for the firewalls:
-A POSTROUTING -t nat -s 192.168.0.2/32 -d 192.168.1.2/32 -j SNAT --to-source 192.168.1.100
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -m state --state INVALID -j DROP
-A FORWARD -m state --state RELATED -j ACCEPT
-A FORWARD -i eth2 -m state --state ESTABLISHED -j ACCEPT
-A FORWARD -i eth1 -p tcp -m tcp --dport 21 --tcp-flags FIN,SYN,RST,ACK SYN -m state --state NEW -j ACCEPT
-A FORWARD -i eth1 -p tcp -m state --state ESTABLISHED -j ACCEPT
-A FORWARD -m state --state INVALID -j LOG --log-prefix "invalid: "
The following steps detail how to check that the expectation support
works fine for conntrackd:
1) You have to enable the expectation support in the configuration
file with the following option:
Sync {
...
Options {
ExpectationSync {
ftp
sip
h323
}
}
}
This enables expectation synchronization for the FTP, SIP and H.323 helpers.
You can alternatively use:
Sync {
...
Options {
ExpectationSync On
}
}
To enable expectation synchronization for all helpers.
2) Make sure you have loaded the FTP helper in both firewalls.
root@fw1# modprobe nf_conntrack_ftp
root@fw2# modprobe nf_conntrack_ftp
3) Switch to the client. Start one FTP control connection to one
server that is protected by the firewalls, enter passive mode:
(term-1) user@client$ nc 192.168.1.2 21
220 dummy FTP server
USER anonymous
331 Please specify the password.
PASS nothing
230 Login successful.
PASV
227 Entering Passive Mode (192,168,1,2,163,11).
This means that port 163*256+11=41739 will be used for the data
traffic. Read this if you are not familiar with the FTP protocol:
http://www.freefire.org/articles/ftpexample.php
3) Switch to fw-1 (primary) to check that the expectation is in the
internal cache.
root@fw1# conntrackd -i exp
proto=6 src=192.168.0.2 dst=192.168.1.2 sport=0 dport=41739 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.0.2 master-dst=192.168.1.2 sport=36390 dport=21 [active since 5s]
4) Switch to fw-2 (backup) to check that the expectation has been successfully
replicated.
root@fw2# conntrackd -e exp
proto=6 src=192.168.0.2 dst=192.168.1.2 sport=0 dport=41739 mask-src=255.255.255.255 mask-dst=255.255.255.255 sport=0 dport=65535 master-src=192.168.0.2 master-dst=192.168.1.2 sport=36390 dport=21 [active since 8s]
5) Make the primary firewall fw-1 fail. Now fw-2 becomes primary.
6) Switch to fw-2 (primary) to commit the external cache into the kernel.
root@fw2# conntrackd -c exp
The logs should display that the commit was successful:
root@fw2# tail -100f /var/log/conntrackd.log
[Wed Dec 7 22:16:31 2011] (pid=19195) [notice] committing external cache: expectations
[Wed Dec 7 22:16:31 2011] (pid=19195) [notice] Committed 1 new entries
[Wed Dec 7 22:16:31 2011] (pid=19195) [notice] commit has taken 0.000366 seconds
7) Switch to the client. Open a new terminal and connect to the port that
has been announced by the server:
(term-2) user@client$ nc -vvv 192.168.1.2 41739
(UNKNOWN) [192.168.1.2] 41739 (?) open
8) Switch to term-1 and ask for the file listing:
[...]
227 Entering Passive Mode (192,168,1,2,163,11).
LIST
9) Switch to term-2, it should display the listing. That means
everything has worked fine.
You may want to try disabling the expectation support and
repeating the steps to check that *it does not work* without
the state-synchronization.
You can also display expectation statistics by means of:
root@fwX# conntrackd -s exp
This update requires no changes in the primary-backup.sh script
that is used by the HA manager to interact with conntrackd. Thus,
we provide a backward compatible command line interface.
Regarding the Filter clause and expectations, we use the master
conntrack to filter expectation events. The filtering is performed
in user-space. No kernel-space filtering support for expectations
yet (this support should go in libnetfilter_conntrack at some
point).
This patch also includes support to disable caching and to allow
direct injection of expectations.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch prepares the introduction of actions with the expectation
table. Mostly renamings.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds a new option TCPWindowTracking that allows not
to disable TCP window tracking as it occurs by default.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the clause `DisableInternalCache' that allows you
to bypass the internal cache. This clause can only be used with
the notrack synchronization mode.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Under stress, the TCP stack may return EAGAIN if there is not
space left in the sender buffer. We also enqueue any other
error.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the clause `DisableExternalCache' that allows you
to disable the external cache and to directly inject the entries
into the kernel conntrack table. As a result, the CPU consumption
of conntrackd increases. This clause can only be used with the
FT-FW and the notrack synchronization modes, but not with the
alarm mode.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the NetlinkEventsReliable clause, this is useful
to turn on reliable Netlink event delivery. This features
requires a Linux kernel >= 2.6.31.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch reworks the commit phase to avoid the forking. This is
particularly useful in active-active setups in which one node
has to commit the external cache while it is receiving new entries
to be added in the external cache. This results in really high
commit times due to the penalty of the copy-on-write that fork
performs.
The default number of steps in one run loop is limited to 64 by now.
No option to tune this parameter is still available via the
configuration file.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the LOCAL_RET_* return values. The return value
LOCAL_RET_STOLEN which allows to leave a client socket open while
waiting for an operation to finish.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch re-introduces `-s queue' but now it displays generic
queue statistics.
# conntrackd -s queue
active queue objects: 0
queue txqueue:
current elements: 0
maximum elements: 2147483647
not enough space errors: 0
queue rsqueue:
current elements: 72
maximum elements: 128
not enough space errors: 0
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch renames the statistics option that displays the content
of the resend queue which is used by the ftfw mode.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the ability to dump the list of existing child
processes. In general, it would be hard to display one since
child processes are generally forked for very specific tasks,
like commit and flush operations, and they have very limited
lifetime. However, this can be handy for debugging problems.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds a dedicated commit handler since there is a possible
race condition that can happen if the child process ends before we
have received all the event messages that the commit request has
triggered.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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In 6f5666a29cb7cbff08ce926ee1edb84a311ff6ee, I moved the flush
operation into a child process and to use a disposable handler
to perform flush requests. This patch adds a dedicated flush
handler since there is a possible race condition that can
happen if the child process ends before we have received all
the event messages that the flush request has triggered.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch is a cleanup, it removes an unused nfct handler. This
removal is due to recent commits that has obsolete it.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch removes the cache write-through clause. This feature
remained undocumented although some has found it looking at the
source code. This feature has remained in the tree for quite
some time although it has several limitations. Moreover, it
is specifically broken and dangerous for Linux kernels >= 2.6.29
since it generates loops in the synchronization.
We do this removal first to prepare the introduction of a feature
to bypass the external cache.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Since Linux kernel 2.6.29, ctnetlink reports the changes that have
been done using ctnetlink. With this patch, conntrackd can recognize
who is the origin of the event messages. For example, this is
interesting to avoid a messy implicit bulk send during the commit
of entries.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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With this patch, you can change the scheduler policy and priority
for conntrackd. Using a RT scheduler policy reduces the chances to
hit ENOBUFS in Netlink.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch removes a couple of constants that have no clients in
the conntrackd code.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch obsoletes the `ListenTo' clause which is a reminiscent
of the intial event filtering code.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch obsoletes `-s multicast' by `-s link' to display the
dedicated link statistics, as the current dedicated link protocol
use can be unicast UDP or multicast. The term "link" is more
generic.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds support for unicast UDP to the channel
infrastructure. With this patch, you can select UDP unicast to
propagate state-changes instead of multicast.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch reworks conntrackd to make it independent of the protocol
used to propagate state-changes. This patch adds the channel layer
abstraction, this layer allows you to add support for different
protocols like unicast UDP or TIPC.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch renames the mcast_iface to interface since this nlif
handler is not related with multicast itself, but to monitor the
link interface used to propagate state-changes. This patch is a
cleanup.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch removes the use of NFCT_DIR_MAX. This constant is part of
the old libnetfilter_conntrack API which has been removed from the
git tree. It was introduced in the early days of conntrackd, thus,
the use of this constant. Unfortunately, I did not notice until now.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch allows flushing the internal and/or the external cache.
The `-f' with no extra parameters still works to flush both the
internal and the external cache.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch fixes the disabling on NetlinkOverrunResync, which
was broken.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds NetlinkOverrunResync. This option can be used to
set the amount of time after which the daemon resynchronizes itself
with the kernel state-table if it detects a Netlink overrun.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch improves the polling support included in 0.9.10. The
polling now consists of getting the state table, wait for PollSecs,
then purge obsolete entries, and so on.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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With this patch, the `-t' option adds an alarm that will flush the
cache after CONFIG(purge_timeout) seconds specified in the config
file. This looks much cleaner and more performance that looping
on the entire conntrack table to set the new timeout of every single
entry.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch obsoletes `DestroyTimeout' which has no clients anymore.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch moves the existing `-v' behaviour to `-s queue' where it
really belongs. The `-v' option is now left to display the version
which is the common use of it.
# conntrackd -v
Connection tracking userspace daemon v0.9.9. Licensed under GPLv2.
(C) 2006-2009 Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the clause PollSecs that changes the normal
behaviour of conntrackd. With PollSecs set to > 0, conntrackd
polls every N seconds the entries.
This is the opposed behaviour of an event-driven behaviour but may
be useful for those that have really strong limitations in terms of
CPU consumption and want to perform a relaxed replication.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch moves the file descriptor registration after the
initialization instead of having a specific hook for this.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch is a cleanup. The overrun handler is actually a way to
resynchronize against the conntrack kernel table. The name overrun
was used because it was initially its purpose. The new naming shows
its genericity.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds support for redundant dedicated links. You can add
a pool of dedicated links that can be used if the current active
fails.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds a generic tx queue for all synchronization modes.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch unifies the tx_list and the tx_queue to have only one
transmission queue. Since the tx_list hold state objects and
tx_queue control messages, I have introduced a queue node type
that can be used to differenciate the kind of information that
the node stores: object or control message.
This patch also reworks the existing queue class to include a
file descriptor that can be used to know if there are new data
added to the queue (see QUEUE_F_EVFD flag).
In this change, I have also modified the current evfd to make the
file descriptor to make read operations non-blocking. Moreover,
it keeps a counter that is used to know how many messages are
inserted in the queue.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Currently, the event handling can starve other event file
descriptors. This patch limits the number of event handling
iterations. The parameter is tunable via configuration file.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds run-time statistics that you can check via
`conntrackd -s runtime'. This information is useful for
trouble-shooting.
This patch replaces several log messages that can be triggered in
runtime. The idea behind this patch is to avoid log message flooding
under errors.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds cache statistics that you can check via
`conntrackd -s cache'. This information is useful for
trouble-shooting.
This patch replaces several log messages that can be triggered in
runtime. The idea behind this patch is to avoid log message flooding
under errors.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds networks statistics that you can check via
`conntrackd -s network'. This information is useful for
trouble-shooting.
This patch replaces several log messages that can be triggered in
runtime. The idea behind this patch is to avoid log message flooding
under errors.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch deletes three unused flags SYNC_MODE_ALARM,
SYNC_MODE_FTFW_BIT and DONT_CHECKSUM. They were replaced by
the CTD_* flags at some point of the development.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch changes the current behaviour of the filtering selection.
Up to now, conntrackd has used the kernel version to select the
filtering method based on the following logic: If kernel is >= 2.6.26
we use BSF-based filtering from kernel-space, otherwise, default to
userspace.
However, this filtering method still lacks of IPv6 support and
it requires a patch that got into 2.6.29 to filter IPv6 addresses
from kernel-space. To fix this issue, we default to user-space
filtering and let the user choose the method via the configuration
file.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch introduces the option `-v' to show useful debugging
information, if any. As for now, only sync-ftfw.c make use of it to
display the content and the length of the resent list/queue. This
is useful to check for message leaks. Other working modes or
synchronization approaches may use it to display debugging
information in the future.
This patch removes _SIGNAL_DEBUG in sync-ftfw.c that was used for
for the same purpose. However, it could only be enabled at compilation
time and it uses signalling instead of the standard UNIX socket
interface that conntrackd provides.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Check if the Linux kernel is >= 2.6.26, otherwise it does not support
kernel-space filtering. This is not clean but we have no choice, the BSF
infrastructure does not return ENOTSUPP for unsupported operations.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the clause PurgeTimeout that sets the new timer
when conntrackd -t is called. This command is particularly useful
when the sysadmin triggers hand-overs between several nodes without
rebooting as it reduces the timers of the remaining entries in
the kernel. Thus, avoiding clashes between new and old entries that
may trigger INVALID packets.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds nl_get_conntrack and it changes the behaviour of
nl_exist_conntrack. Now, nl_get_conntrack requests the kernel for
a conntrack and updates the cached entry. On the other hand,
nl_exist_conntrack only inquiries for the existence of the
entry.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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