Bug 112630 - 2.6: /sbin/service iptables stop hangs on modprobe -r ipt_state
Summary: 2.6: /sbin/service iptables stop hangs on modprobe -r ipt_state
Status: CLOSED DUPLICATE of bug 212839
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.0
Hardware: All
OS: Linux
Target Milestone: ---
: ---
Assignee: Thomas Graf
QA Contact: Brian Brock
Keywords: Reopened
: 143731 147386 (view as bug list)
Depends On:
TreeView+ depends on / blocked
Reported: 2003-12-25 01:07 UTC by Kaj J. Niemi
Modified: 2018-12-05 15:08 UTC (History)
16 users (show)

Clone Of:
Last Closed: 2006-11-22 19:05:04 UTC

Attachments (Terms of Use)
proposed patch (1.79 KB, patch)
2005-03-15 05:12 UTC, Phil Oester
no flags Details | Diff
proposed patch (1.08 KB, patch)
2005-03-30 15:52 UTC, Phil Oester
no flags Details | Diff
Updated information/output for this bug (1.55 KB, text/plain)
2006-09-04 05:26 UTC, David O'Brien
no flags Details

Description Kaj J. Niemi 2003-12-25 01:07:58 UTC
Description of problem:
Doing /sbin/service iptables stop seems to hang on modprobe -r
ipt_state. /etc/sysconfig/iptables looks as follows:

# Firewall configuration written by lokkit
# Manual customization of this file is not recommended.
# Note: ifup-post will punch the current nameservers through the
#       firewall; such entries will *not* be listed here.
-A INPUT -i lo -j ACCEPT
# -A INPUT -m state --state NEW -p tcp --dport 25 -j ACCEPT
-A INPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT
:RH-Lokkit-0-50-INPUT - [0:0]
-A INPUT -j RH-Lokkit-0-50-INPUT
-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 69 -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A RH-Lokkit-0-50-INPUT -i lo -j ACCEPT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 0:1023 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 2049 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 0:1023 -j REJECT
-A RH-Lokkit-0-50-INPUT -p udp -m udp --dport 2049 -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 6000:6009 --syn -j REJECT
-A RH-Lokkit-0-50-INPUT -p tcp -m tcp --dport 7100 --syn -j REJECT

This seems similar to bug #103177 but that was with 2.4 kernels.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. /sbin/service iptables stop (or /etc/init.d/iptables stop)
Actual results:

Expected results:
Should work properly.

Additional info:

Comment 1 Thomas Woerner 2004-01-07 15:06:29 UTC
mm.. I can not reproduce your problem with 


What exactly are you doing for this to happen?

Comment 2 Arjan van de Ven 2004-01-07 15:29:40 UTC
rmmod of iptables needs to wait until all active state is gone from
the kernel, eg all masqueraded connections need to be terminated etc
etc etc.
That can take some time......

Comment 3 Kaj J. Niemi 2004-02-13 09:40:39 UTC
Unable to reproduce on kernel-2.6.2-1.74, iptables-1.2.9-1.2. I'll
close for now.

Comment 4 Kaj J. Niemi 2004-06-07 22:55:57 UTC
This seems to happen intermittently on 2.6.4+ FC2 kernels again. What
really happens is that modprobe/rmmod is eating 99% of the CPU.

When upgrading iptables and/or restarting them it is almost always
necessary to reboot the server(s) which not only is annoying but a bit
dangerous too. ;-)

rmmod really can't wait until all active state is gone (I believe this
didn't happen on the 2.4 kernels) because that might take more than a
reasonable while and really have an impact on how the system works.

Comment 5 Kaj J. Niemi 2004-06-07 22:57:06 UTC
% rpm -q kernel iptables iptables-ipv6

Comment 6 Michael Schwendt 2004-06-08 00:14:19 UTC
With kernel 2.4 I've added some comments on the lock-up here:

In particular, 'cat /proc/net/ip_conntrack' is empty, so I fail to see
where masqueraded connections would be involved at all.

Comment 7 Norman Elton 2004-08-03 01:18:48 UTC
I'm getting the same problems on my 2.4.21-15.0.3EL kernel. I'm using conn_track and 
ipv4_forwarding. iptables version 1.2.8-12.3

Comment 8 Kaj J. Niemi 2004-08-31 14:02:09 UTC
This happens every now and then but I'm unsure how to proceed with
this. In my opinion this is a big bug as sometimes /sbin/service
iptables restart results in the system being pretty much unusable
until a reboot is issued. Rebooting a firewall or a desktop box just
because one changed the packet filter things is a major pain in the
ass ;-)

Comment 9 Jarrod O'Connell 2004-09-14 06:57:29 UTC
Fedora Core 2

% rpm -q kernel iptables

% service iptables restart
Flushing firewall rules:                                   [  OK  ]
Setting chains to policy ACCEPT: filter                    [  OK  ]
Unloading iptables modules:

This is where it hangs...

Comment 10 Dave Jones 2004-12-08 07:00:27 UTC
is this still a problem with the latest updates ?

Comment 11 Kaj J. Niemi 2004-12-08 09:46:40 UTC
Happens unfrequently but is still there...

Comment 12 Sergey V. Udaltsov 2004-12-20 20:42:25 UTC
Same here...

/etc/init.d/iptables restart

called inside /sbin/ifdown-local

CPU goes 99% and never returns back till reboot

Comment 13 steve 2004-12-22 19:00:55 UTC
Problem still here...

Fedora Core 3

% rpm -q kernel iptables

% top

 2713 root      25   0  1592  408 1336 R 99.8  0.0   0:30.29 modprobe
    1 root      16   0  3196  564 1408 S  0.0  0.1   0:01.01 init

% /sbin/service iptables stop
Flushing firewall rules:                                   [  OK  ]
Setting chains to policy ACCEPT: filter                    [  OK  ]
Unloading iptables modules:

Comment 14 Michael Katzmann 2005-01-24 20:05:34 UTC
This happens on mys system. 
Kernel 2.6.10-741_FC3smp and iptables-1.2.11-3.2

Comment 15 Martin Ebourne 2005-01-28 21:37:55 UTC
I've got this too. Exactly as described by the posters above, appears
to hang, uses all the cpu etc.

This is a new laptop with a fresh install of FC3, and all updates
applied. Currently at:

kernel-2.6.10-1.741_FC3, iptables-1.2.11-3.1.FC3.

It is completely reproduceable for me. ie. It happens any time there
is a network configured. If I boot up with no network configured at
all it works fine. As soon as I've done 'ifconfig ethX' it
breaks, whether ethX is the inbuilt wireless or lan. This clearly
isn't to do with outstanding connections.

I've never seen this on any of my other machines (desktops or
laptops), and they all run FC3, mostly with the same versions of

I see you've marked this as 'NEEDINFO'. What info do you need? I read
the other comments & didn't get any hints.

For now I stuck 'return 0' at the start of rmmod_r(), not ideal.

Comment 16 Chip Mefford 2005-01-31 19:00:41 UTC
I also am seeing this.

on an /etc/init.d/iptables stop, reload or whatever,

modprobe -r ipt_state hangs like a hat on rack.

As the machine I am trying to configure is about 6 hours driving
time away, I have to quite literally toss it a reboot every
time I need to make a change to iptables.

What a pain!

FC3, fully patched and updated via yum as of 200501311300 EST.

Using the FC3 default whatevers 

kernel 2.6.10-1.741_FC3 stock build, 

Comment 17 Tadej Janež 2005-02-01 11:38:14 UTC
The same thing happens on my laptop (running updated FC3) but only when
NetworkManager daemon is running.

Relevant versions:

I've tried with all three kernels and it's always the same.

I think it might be worth investigating why NetworkManager is causing 'service
iptables stop' to hang.

Comment 18 Martin Ebourne 2005-02-01 12:10:17 UTC
NetworkManager may well be it. The only machine I have which has this problem is
also the only one running NetworkManager, though it happens regardless of
whether NetworkManager configures the interface or I do it manually.

Comment 19 Kaj J. Niemi 2005-02-01 12:32:04 UTC
Martin, the bug has been around well before NetworkManager was conceived :)

Comment 20 Mike Breen 2005-02-27 08:33:27 UTC
I have the same problem with, albeit with a custom 2.6.10 kernel.
Symptoms are the same, ie. "modprobe -r ipt_state" is taking
99% CPU if I change the firewall settings. Before I tried doing
this, my PC was hanging at system shutdown at "Stopping iptables:"
so that I had to do a hard reset.
As reported above, it manifests itself only if a network is 

I think this is quite serious. It seems to have been an on and off
problem, e.g. bug 99057.

Comment 21 Mike Breen 2005-02-27 10:26:26 UTC
Sorry, didn't have time to include more info in last comment...

kill -9 xxxx # kill modprobe process - has no effect

This was not a problem with FC1; I skipped FC2; FC3 was a new install
kernel - my own 2.6.10 (but derived from Red Hat .config)

The PC is a dell inspiron 8600.
The only irregularity I can think of is that I installed linuxant's
hsfmodem driver right after FC3 installation and new kernel and I
know that changed /etc/modprobe.conf (and modules.conf).

Comment 22 Jay Turner 2005-03-01 12:33:34 UTC
*** Bug 143731 has been marked as a duplicate of this bug. ***

Comment 23 Jay Turner 2005-03-01 12:34:08 UTC
*** Bug 147386 has been marked as a duplicate of this bug. ***

Comment 24 Jay Turner 2005-03-01 12:39:50 UTC
Bug 146753 is the same problem but against NetworkManager and I'm not really
sure who's at fault so leaving both bugs open.

Comment 25 Kaj J. Niemi 2005-03-01 12:43:42 UTC
When I originally reported the bug there was no NetworkManager around. The bug
works in the same way as the older bug for FC1 kernels.

Comment 26 Jake 2005-03-01 14:21:38 UTC
I'm getting this exact same problem too.

[root@laptop ~]# rpm -q kernel iptables NetworkManager

But network manager is NOT running for me.

I keep up to date with nightly yum updates. Last time I tried a
'service iptables stop' was a week ago and it worked fine. Today it's
not working.

Comment 27 Jake 2005-03-01 14:54:03 UTC
I have a work-around to saves me from having to restart. I have two
network devices: eth0 (wired ethernet) and eth1 (wireless ethernet). I
just do:

[root@laptop ~]# ifdown eth1

... and immediately the hanging process finishes giving an OK/success

I then bring eth1 bank online with

[root@laptop ~]# ifup eth1

Having done this once, I then seem able to do

[root@laptop ~]# service iptables stop

etc. as much as I want without it hanging again.

HOWEVER... if I do a fresh system reboot I then have to put eth1 down
again to remove the hang. But only once per reboot it would seem.

Comment 28 Phil Oester 2005-03-04 23:53:45 UTC
Jake: Could you provide a copy of your iptables rules from this box? 
Does the box serve as a gateway?  Any NAT?  What extra iptables
modules do you load?  Does the problem still exist even if no traffic
has gone through the box (i.e. immediately after reboot)?

Comment 29 Curtis Doty 2005-03-07 07:08:10 UTC
Same symptom here on fresh FC3. I did two things and problem went
away. Maybe it is one of these?

 - disabled ipv6
 - boot to 2.6.10-1.770_FC3smp

Problem occured here under kernel build 766. And with only the filter
table loaded with conntrack and the standard set of matches.

Comment 30 Jake 2005-03-07 09:57:52 UTC
Here's my iptables for you Phil. The machine is my laptop on which I
develop websites and allow other computers access to them through the
firewall. I've also played around with it as a mail server to find out
how to get things working well. I'm not sure about immediately after
reboot. How would I find out which extra iptables modules I load? I'm
very new to Linux still.

[root@laptop ~]# service iptables status
Table: filter
Chain INPUT (policy ACCEPT)
target     prot opt source               destination
RH-Firewall-1-INPUT  all  --  

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
RH-Firewall-1-INPUT  all  --  

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain RH-Firewall-1-INPUT (2 references)
target     prot opt source               destination
ACCEPT     all  --  
ACCEPT     icmp --             icmp type 255
ACCEPT     esp  --  
ACCEPT     ah   --  
ACCEPT     udp  --           udp dpt:5353
ACCEPT     udp  --             udp dpt:631
ACCEPT     all  --             state
ACCEPT     tcp  --             state NEW
tcp dpt:443
ACCEPT     tcp  --             state NEW
tcp dpt:10000
ACCEPT     tcp  --             state NEW
tcp dpt:22
ACCEPT     tcp  --             state NEW
tcp dpt:25
ACCEPT     tcp  --             state NEW
tcp dpt:80
REJECT     all  --            
reject-with icmp-host-prohibited

Comment 31 Phil Oester 2005-03-15 05:12:08 UTC
Created attachment 112005 [details]
proposed patch

The attached fixes the problem for me.	Full explanation of problem and patch
available here:


Testing appreciated...

Comment 32 Hugues Dufour 2005-03-29 02:37:11 UTC
Personnaly, stopping iptables takes all CPU whenever eth0 has "Activate device
when computer starts" set to false in system-config-network and eth0 is up.

So the workaround for me is just to set this flag to true. One strange thing
though is that eth0 is not up if I reboot the system. I have to activate it by
hand. My numerous tests to have this issue solved may have caused some
collateral damages.

BTW, I tried both 2.6.10-1.770_FC3 and 2.6.9-1.667 kernels and I got the same

Comment 33 Phil Oester 2005-03-30 15:52:44 UTC
Created attachment 112459 [details]
proposed patch

Attached is a better patch which fixes the core problem -- the prior was a

Comment 34 Simon Goodall 2005-04-17 16:18:58 UTC
I have had similar problems since I have had NetworkManager installed --
occasional hanging during shutdown of iptables. However lately playing around
with my firewall settings, I have noticed that if it hangs, I can stop (or
restart) my NetworkManager service and modprobe then completes.

Comment 35 Gunther Richter 2005-05-04 03:51:50 UTC
Got the same problem with 2.6.11-1.1226_FC4smp. Whenever I try to either 
shutdown iptables or do a restart 'service iptables restart', the process hangs 
and modprobe takes 99% of the cpu time. Have to reboot for every iptables 

Comment 36 Gunther Richter 2005-05-05 05:48:54 UTC
(In reply to comment #35)
> Got the same problem with 2.6.11-1.1226_FC4smp. Whenever I try to either 
> shutdown iptables or do a restart 'service iptables restart', the process hangs 
> and modprobe takes 99% of the cpu time. Have to reboot for every iptables 
> change.

Installed Turtelfirewall 1.28 (webmin ...wbm.gz) and it is now possible to apply
changes without rebooting, while using the init.d/iptables script for
stopping/restarting still loops on modprobe.

Comment 37 Dave Jones 2005-07-15 18:03:19 UTC
An update has been released for Fedora Core 3 (kernel-2.6.12-1.1372_FC3) which
may contain a fix for your problem.   Please update to this new kernel, and
report whether or not it fixes your problem.

If you have updated to Fedora Core 4 since this bug was opened, and the problem
still occurs with the latest updates for that release, please change the version
field of this bug to 'fc4'.

Thank you.

Comment 38 Tadej Janež 2005-07-15 19:33:46 UTC
I've since updated my laptop to Fedora Core 4 and I'm happy to report that this
problem is now gone (for me, at least).

Comment 39 Dave Jones 2005-10-03 00:30:31 UTC
This bug has been automatically closed as part of a mass update.
It had been in NEEDINFO state since July 2005.
If this bug still exists in current errata kernels, please reopen this bug.

There are a large number of inactive bugs in the database, and this is the only
way to purge them.

Thank you.

Comment 40 David O'Brien 2006-09-04 05:26:48 UTC
Created attachment 135480 [details]
Updated information/output for this bug

Comment 41 Kaj J. Niemi 2006-09-04 09:03:44 UTC
I would still claim that restarting all networking is not really a good workaround for servers with iptables 
but then again I guess everybody just outsources the packet filtering to a vendor C or vendor J box instead 
of keeping them on the servers?

Comment 42 Bill Nottingham 2006-11-22 19:05:04 UTC

*** This bug has been marked as a duplicate of 212839 ***

Comment 43 Kaj J. Niemi 2006-11-22 19:07:14 UTC
the bug which this is a duplicate of is marked private

Comment 44 xingxing 2012-11-29 10:39:48 UTC
i got this trouble again

Comment 45 xingxing 2012-11-29 11:03:29 UTC
#uname -r 
RHEL6.3 x86_64

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