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ip_conntrack: CT 0: table full, dropping packet. [message #37827]

Tue, 27 October 2009 01:55

mavines
Messages: 4
Registered: October 2009

Junior Member

Hi,

I have the major problem with networking - /var/log/messages reports this:
ip_conntrack: CT 0: table full, dropping packet.

And I have CentOS 5.4, kernel:

Linux 2.6.18-128.2.1.el5.028stab064.7xen #1 SMP Wed Aug 26 16:41:55 MSD 2009 x86_64 x86_64 x86_64 GNU/Linux

# ip rule list
0: from all lookup 255
32766: from all lookup main
32767: from all lookup default

the iptables rules are attached, tcpdump is attached as well.

here is the lsmod of main server:
Module Size Used by
iptable_nat 43532 0
tun 47872 2
xt_physdev 35984 0
bridge 94384 1 xt_physdev
netloop 40324 0
netbk 129984 0 [permanent]
blktap 151460 2 [permanent]
blkbk 54712 0 [permanent]
vzethdev 47520 0
vznetdev 56848 8
simfs 38296 4
vzrst 172968 0
ip_nat 53392 2 iptable_nat,vzrst
vzcpt 150840 0
vzdquota 78320 4 [permanent]
vzmon 83864 8 vzethdev,vznetdev,vzrst,vzcpt
vzdev 36872 4 vzethdev,vznetdev,vzdquota,vzmon
xt_tcpmss 35328 0
ipt_tos 34560 0
xt_tcpudp 36224 245
xt_conntrack 36352 0
ip_conntrack_irc 41168 0
xt_state 35200 23
ip_conntrack_ftp 42192 0
xt_multiport 36224 4
xt_length 34944 0
xt_mac 34944 0
xt_limit 36352 46
ipt_TCPMSS 37248 1
iptable_mangle 37888 5
iptable_filter 37760 6
ipt_TOS 35200 14
ipt_ULOG 42504 0
ip_conntrack 100884 8 iptable_nat,vzrst,ip_nat,vzcpt,xt_conntrack,ip_conntrack_irc ,xt_state,ip_conntrack_ftp
ipt_recent 43404 45
ipt_ecn 35200 0
ipt_owner 34944 0
ip_tables 57440 3 iptable_nat,iptable_mangle,iptable_filter
ipt_ttl 34816 0
ipt_REJECT 39684 42
ipt_LOG 39808 40
nfnetlink 40392 2 ip_nat,ip_conntrack
x_tables 52616 21 iptable_nat,xt_physdev,xt_tcpmss,ipt_tos,xt_tcpudp,xt_conntr ack,xt_state,xt_multiport,xt_length,xt_mac,xt_limit,ipt_TCPM SS,ipt_TOS,ipt_ULOG,ipt_recent,ipt_ecn,ipt_owner,ip_tables,i pt_ttl,ipt_REJECT,ipt_LOG
autofs4 57480 2
hidp 83584 2
rfcomm 104872 0
l2cap 89216 10 hidp,rfcomm
bluetooth 118916 5 hidp,rfcomm,l2cap
lockd 101776 0
sunrpc 201416 2 lockd
ipv6 456124 435 vzrst,vzcpt,vzmon
xfrm_nalgo 43268 1 ipv6
crypto_api 42880 1 xfrm_nalgo
ib_iser 66936 0
rdma_cm 67092 1 ib_iser
ib_cm 67752 1 rdma_cm
iw_cm 43400 1 rdma_cm
ib_sa 74760 2 rdma_cm,ib_cm
ib_mad 70820 2 ib_cm,ib_sa
ib_core 93700 6 ib_iser,rdma_cm,ib_cm,iw_cm,ib_sa,ib_mad
ib_addr 42128 1 rdma_cm
iscsi_tcp 57856 0
libiscsi 63488 2 ib_iser,iscsi_tcp
scsi_transport_iscsi 66960 5 ib_iser,iscsi_tcp,libiscsi
loop 48656 4
dm_mirror 54280 0
dm_multipath 55192 0
scsi_dh 41600 1 dm_multipath
raid0 40448 1
video 53004 0
hwmon 36488 0
backlight 39808 1 video
sbs 49856 0
i2c_ec 38528 1 sbs
container 37760 0
button 40480 0
battery 43784 0
asus_acpi 50724 0
ac 38664 0
lp 47056 0
snd_hda_intel 481584 0
snd_seq_dummy 36996 0
snd_seq_oss 65408 0
snd_seq_midi_event 40960 1 snd_seq_oss
snd_seq 87968 5 snd_seq_dummy,snd_seq_oss,snd_seq_midi_event
snd_seq_device 41492 3 snd_seq_dummy,snd_seq_oss,snd_seq
snd_pcm_oss 77440 0
snd_mixer_oss 49920 1 snd_pcm_oss
snd_pcm 116872 2 snd_hda_intel,snd_pcm_oss
snd_timer 57224 2 snd_seq,snd_pcm
snd_page_alloc 43920 2 snd_hda_intel,snd_pcm
r8169 71172 0
snd_hwdep 43528 1 snd_hda_intel
snd 99496 9 snd_hda_intel,snd_seq_oss,snd_seq,snd_seq_device,snd_pcm_oss ,snd_mixer_oss,snd_pcm,snd_timer,snd_hwdep
mii 38784 1 r8169
i2c_i801 41620 0
soundcore 41760 1 snd
parport_pc 62248 1
pcspkr 36224 0
i2c_core 56064 2 i2c_ec,i2c_i801
ohci1394 67928 0
shpchp 70572 0
parport 73868 2 lp,parport_pc
ieee1394 390648 1 ohci1394
r8168 95000 0
sg 69544 0
serial_core 56192 0
dm_raid45 98704 0
dm_message 36096 1 dm_raid45
dm_region_hash 46336 1 dm_raid45
dm_log 44800 3 dm_mirror,dm_raid45,dm_region_hash
dm_mod 100560 4 dm_mirror,dm_multipath,dm_raid45,dm_log
dm_mem_cache 39424 1 dm_raid45
ahci 68744 4
libata 208784 1 ahci
sd_mod 56448 7
scsi_mod 197528 8 ib_iser,iscsi_tcp,libiscsi,scsi_transport_iscsi,scsi_dh,sg,l ibata,sd_mod
ext3 168848 2
jbd 102512 1 ext3
uhci_hcd 57496 0
ohci_hcd 55988 0
ehci_hcd 65676 0

So, firstly I had a problem with orphaned sockets (it persisted about 6 months, but I did not paid enough attention), then server started to fail and I somehow fixed the problem with orphaned sockets at CT300. But instead I've got the problem with ip_conntrack which lasts for 2 weeks already and I am not able to figure out why.

sysctl -A output is also attached.

So, my server for now gets overflowed at least once by day and I have to increase max value for ip_conntrack, but this helps only for few hours, then I have to reboot the server or it just hangs without response.

I was suspecting that this is an attack (like DDoS) but even when the server has very few connections, it gets overflowed. And that is really nasty.

Can you please help with that?

Yes, another detail - I have 4 OpenVZ VPSs and 2 XEN VPSs running on the same server. It has 8 GB RAM and 1.5 TB HDD - Core Quad Intel CPU.

Attachment: iptables_rules.txt
(Size: 28.56KB, Downloaded 538 times)
Attachment: tcpdump.txt
(Size: 1.80KB, Downloaded 503 times)
Attachment: sysctl.txt
(Size: 32.36KB, Downloaded 527 times)

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Re: ip_conntrack: CT 0: table full, dropping packet. [message #37828 is a reply to message #37827]

Tue, 27 October 2009 09:33

kir
Messages: 1645
Registered: August 2005
Location: Moscow, Russia

Senior Member

This is not really openvz specific, google for ip_conntrack table full dropping packet and you will find the answers.

In short -- check why there are so many entries by analyzing /proc/net/ip_conntrack, and either fix the issues found (maybe somebody is attacking you), or increase /proc/sys/net/ipv4/ip_conntrack_max.

Kir Kolyshkin

http://static.openvz.org/userbars/openvz-developer.png

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Re: ip_conntrack: CT 0: table full, dropping packet. [message #37829 is a reply to message #37828]

Tue, 27 October 2009 10:59

mavines
Messages: 4
Registered: October 2009

Junior Member

Thanks for the answer. Obviously I did the google search for my problem. I thought it is attack - but really it is not. Even my own connections to server stays in the /proc/net/ip_conntrack for long time. As I told, I was increasing the /proc/sys/net/ipv4/ip_conntrack_max even 4x, but still this does not fix the issue. Further more, as soon as OpenVZ (service vz restart) restart - the /proc/sys/net/ipv4/ip_conntrack_max comes back to initial value. Even though I have it hard written in the /etc/sysctl.conf file. So, I am actually not able to fix the issue myself. I was trying to do this for 2 weeks long and still no good solution. Most of google search advices to increase max conntack number. I did so. Others tell that this is possibly attack - I've blocked almost the whole internet - still nothing - conntrack stack gets full once per day. So, I hope OpenVZ gurus can advice something here.

Thanks and regards,
Maksym.

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Re: ip_conntrack: CT 0: table full, dropping packet. [message #37831 is a reply to message #37829]

Tue, 27 October 2009 11:13

mavines
Messages: 4
Registered: October 2009

Junior Member

in addition - all connections, which are in /proc/net/ip_conntrack
are to CT 300 IP to port 80. And CT 300 is the exact OpenVZ VPS which previously had issues with orphaned sockets. So, previously it throwed this error:
Orphaned socket dropped (187,374 in CT300)
For now it throws this:
ip_conntrack: CT 0: table full, dropping packet.

But still all connections which are in /proc/net/ip_conntrack goes to CT 300 - apache. The main hardware server (CT 0) does not have apache installed at all.

Regards,
Maksym.

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Re: ip_conntrack: CT 0: table full, dropping packet. [message #37832 is a reply to message #37831]

Tue, 27 October 2009 12:54

kir
Messages: 1645
Registered: August 2005
Location: Moscow, Russia

Senior Member

Do you have any UBC failures for CT300?

Kir Kolyshkin

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Re: ip_conntrack: CT 0: table full, dropping packet. [message #37835 is a reply to message #37832]

Tue, 27 October 2009 14:04

mavines
Messages: 4
Registered: October 2009

Junior Member

Here are UBC dump for CT300:

vzctl exec 300 cat /proc/user_beancounters
Version: 2.5
       uid  resource                     held              maxheld              barrier                limit              failcnt
      300:  kmemsize                 24701900             42827273             57490800             59160657                    0
            lockedpages                     0                    0                 1024                 1024                    0
            privvmpages                331898               420450               524288               524288                    0
            shmpages                      925                 1581                86016                86016                    0
            dummy                           0                    0                    0                    0                    0
            numproc                       235                  368                  960                  960                    0
            physpages                   74167                94828                    0           2147483647                    0
            vmguarpages                     0                    0               135168           2147483647                    0
            oomguarpages                74167                94828               104448           2147483647                    0
            numtcpsock                    103                  303                 1440                 1440                    0
            numflock                        4                    8                  752                  824                    0
            numpty                          1                    2                   64                   64                    0
            numsiginfo                      0                   12                 1024                 1024                    0
            tcpsndbuf                  855824              1366528              6881280             10813440                    0
            tcprcvbuf                  844976              1226352              6881280             10813440                    0
            othersockbuf               356496               497248              4504320              8388608                    0
            dgramrcvbuf                     0                70464              1048576              1048576                    0
            numothersock                  165                  194                 1440                 1440                    0
            dcachesize                      0                    0             13639680             14499840                    0
            numfile                      3786                 5048                37248                37248                    0
            dummy                           0                    0                    0                    0                    0
            dummy                           0                    0                    0                    0                    0
            dummy                           0                    0                    0                    0                    0
            numiptent                      10                   10                  512                  512                    0

[Updated on: Tue, 27 October 2009 14:11] by Moderator

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