[DRBD-user] Conflict between drbd and iptables

Gary W. Smith gary at primeexalia.com
Wed Aug 2 21:23:29 CEST 2006

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Gary Wayne Smith

> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com [mailto:drbd-user-
> bounces at lists.linbit.com] On Behalf Of Gary W. Smith
> Sent: Wednesday, August 02, 2006 7:43 AM
> To: CHARTON Yannick; drbd-user at linbit.com
> Subject: RE: [DRBD-user] Conflict between drbd and iptables
> 
> Simplify your life and find out what IPTables thinks is the problem.
> After all, it's the one blocking the packets.  Just log before the
drop.
> 
> -A RH-Firewall-1-INPUT -j LOG --log-prefix "FIREWALL: " --log-level 6
> -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
> 
> Then watch which DRBD packets are failing by doing a simple tail -n -f
> /var/log/messages.
> 
> Or
> 
> Spend a week guessing ;)
> 
> Gary Wayne Smith
> 
> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com
> [mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of CHARTON
Yannick
> Sent: Wednesday, August 02, 2006 1:27 AM
> To: drbd-user at linbit.com
> Subject: [DRBD-user] Conflict between drbd and iptables
> 
> Hi,
> 
> I'm using drbd 0.7.17 to synchronise two nodes (running on Red Hat
> Entreprise Linux 4) with a dedicated gigabyte link between the two
> nodes.
> All drbd.conf parameters are set to very common values.
> 
> My problem seems to be a conflict between drbd and the iptables
firewall
> :
> 
> My iptables configuration on the two nodes includes the line :
> -A RH-Firewall-1-INPUT -s NODE_IP_ADDRESS -p tcp --dport 7789 -j
ACCEPT
> 
> When I start the two nodes, there is no problem. However, when I
> restart the firewall on the secondary node, I receive a flow of
> messages :
> kernel: drbd0: [kjournald/2927] sock_sendmsg time expired, ko =
> 4294967295
> kernel: drbd0: [kjournald/2927] sock_sendmsg time expired, ko =
> 4294967294
> ...
> And the web services (apache) are unavailable.
> 
> I tested without iptables, then with iptables on the primary node (and
> tried to start and restart iptables service). No problem. But when I
> tried to start iptables on the second node, I received the message
flow
> on the first node (and nothing in the log of the second node). I have
> to stop the drbd service on the secondary, then to restart the
service,
> and all the systems fonction right again.
> 
> I will try to reproduce the problem with a test architecture (I don't
> have a full time access to the servers, and I prefered to stop
iptables
> service while I work on a solution). Unfortunately, I have no logs
> about packets which are droped by iptables, but I will add it on my
> test architecture.
> 
> However, if you have an idea, if you already met this problem, or
> simply if you can help me, your help will be very precious !
> 
> Thank you very much !
> 
> Yannick CHARTON
> 
> 
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