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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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The ct object that is passed as parameter is not modified,
make it constant.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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We now include one pointer to the object in the extra section.
This is required to generalize this code for the expectation
support. We consume 4-8 bytes extra, but we will not need more
changes to support expectations which is a good idea.
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This patch simplifies cache_get_extra which now takes only one
parameter that is the cache_object. With it, the extra area can be
calculated.
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 generalizes the network message building and parsing
to prepare the upcoming expectation support.
Basically, it renames:
- NET_T_STATE_* by NET_T_STATE_CT_*, as I plan to add NET_T_STATE_EXP_*
- BUILD_NETMSG by BUILD_NETMSG_FROM_CT, and build_payload by ct2msg.
I plan to add exp2msg.
- parse_payload by msg2ct, since I plan to add msg2exp.
- modify object_status_to_network_type to prepare the support of
expectations.
- add prefix ct_ to all parsing functions in parse.c, as we will have
similar functions to convert messages to expectation objects.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch contains cleanups to prepare the expectation support for
external handlers. Mostly renamings.
I have also updated the file headers to include Vyatta in the copyright
statement.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch generalizes the caching infrastructure to store different
object types. This patch is the first in the series to prepare
support for the synchronization of expectations.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch improves the case in which we receive a commit request
but we are already performing one. This behaviour is suspicious
since the HA manager should not trigger a double master transition.
Otherwise, something probably is not configured appropriately.
This improves 98756c2608f0879a2322919c7441973216565272
"cache: close commit request if we already have one in progress".
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds `--zone' to the command line tool. This adds
the missing user-space support for Patrick's McHardy iptables
CT target.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds the --any-nat option that allows to display src-NATted
OR dst-NATted flows.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch is a cleanup, it puts all the commands and options code
together. This makes easier and less error-prone the task to add
new commands and options.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch fixes a hung that occurs if you invoke `conntrackd -c'
and you have disabled the external cache.
Note that `conntrackd -c' does nothing since there is no entries
in the external cache to be committed.
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 state-synchronization for ICMP. You SHOULD use a
Linux kernel >= 2.6.31, otherwise this patch can result in tons
of state-updates.
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 fixes a bug in the TCP support that breaks
re-connections of the client side if several TCP
channels are used in the configuration file.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Use the TCP header size (20 bytes) instead of the UDP header size
(8 bytes) to calculate the maximum packet size.
Reported-by: Samuel Gauthier <samuel.gauthier@6wind.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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We cannot assume that we will not write in the net message before we
send it, because the memory allocated for the net message (__net) is
only reserved in BUILD_NETMSG (because of the { } block in it).
This patch marks the buffer as static to avoid this problem.
Based on a patch from Samuel Gauthier <samuel.gauthier@6wind.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds support for TCP as protocol to replicate
state-changes between two daemons. Note that this only
makes sense with the notrack mode.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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With this patch, we can remove file descriptors dinamically
from our own file descriptor pool.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch reduces the number of gettimeofday syscalls by caching
the current time in a variable at the beginning of the main loop.
Based on a suggestion from Vincent Jardin.
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 missing support to filter IPv6 from kernel-space
by means of the BSF API that libnetfilter_conntrack provides.
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 cache_iterate_limit() and hashtable_iterate_limit()
that allows to limit the iteration to given a number of states.
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 adds a new statistic field to count the number of
enospc errors while adding new nodes to some queue.
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 adds the name field to identify the queue by means of
a string. This patch is used by the next one that introduces
per-queue statistics.
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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In 400ae54438c4b85126f9fab0ae1dc067823b70f7, we added the SCTP
support by means of a structure that was encapsulated in an
TLV attribute. However, this structure didn't handle alignment
and endianess issues appropriately. Similar problem was
introduced in b808645ec71b7cc22cf5106b3d79625d07e6077c along
with the DCCP support.
This patch moves every field of this structure to independent
attributes. I decided not to use nesting to make building and
parsing more simple.
Using TLV is a good idea, specially for DCCP and SCTP that are
under development and that may include new fields and obsolete
them in the future.
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 allows to limit the number of simultaneous child processes.
This is required by the next patch that replaces disposable handlers
to commit and flush with permanent handlers.
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 a reminiscent of the lifetime cache feature.
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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With this patch, the flush operation is performed by a child process.
Thus, the parent process digests destroy events that ctnetlink reports
back and, thanks to the origin infrastructure, we skip the messy
implicit synchronization that are triggered by such events.
This patch requires a Linux kernel >= 2.6.29 to benefit from this
change, otherwise it has no effect.
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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This patch adds a simple infrastructure that allows to account
the child processes that have been forked. This also includes
a callback handler that can be registered that is called once
the child process finishes.
We can extended this later to include an alarm to limit the
maximum lifetime of a forked child process. This is good to
ensure that child processes behave timely.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds initial support for DCCP state replication.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds initial support for SCTP state replication.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds GRE support for the command line tool conntrack.
With this patch, we support all protocols available in the kernel.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.
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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 adds DCCP support for the command line tool conntrack.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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This patch adds SCTP support to the command line tool conntrack.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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