Firewall problem with Virtualmin on Centos

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1

Hi,

I’m trying to setup Virtualmin GPL on a CentOS 5.5 server and I can complete the installation fine.

Once it’s installed I add the extra IPs assigned to the server and setup the DNS. Everything works fine for a while then randomly I will lose all connection with the server and it appears as if a firewall has blocked all ports.

When this happened the first time I decided to do a fresh install after reinstalling CentOS thinking that maybe I’d misconfigured something however the problem happened again a second time.

I’m now wondering if I’m messing something up during the configuration which is causing this problem however I can’t think what it may be. I make no changes to the firewall at any point.

Is there a default firewall configuration which comes with Virtualmin? Am I missing an important step somewhere?

Basically I do the following:

  • Fresh CentOS install.
  • wget install.sh and run the installation.
  • Login to Virtualmin and add the 2 extra IPs as virtual interfaces on eth0
  • Everything runs fine for maybe an hour or so then all of a sudden I’m disconnected and can’t connect to the server through SSH or Virtualmin.

The IPs are added correctly and once I’ve created a virtual server through virtualmin I can get everything to resolve to the server.

Anything I should look for that can help me solve this? Would using Ubuntu or another distribution have the same problem?

Thanks for your help.

2

Howdy,

What you’re seeing isn’t a normal problem… that almost sounds like a network issue of some sort.

If a network interface is up and running now, it should still be running after a few hours… if it isn’t, something is quite awry!

Virtualmin doesn’t setup any sort of defauly firewall.

In diagnosing your issue, you may want to run “dmesg”, and look towards the end of the output to see if there’s any network related errors that show up.

Also, are any of the IP’s on your server pingable when this problem is happening, or is it completely unavailable?

-Eric

3

Ok it’s back online now after a remote reboot, but I still don’t know what the issue is. I am pretty sure it’s related to Virtualmin as before installing it, it ran for almost a day whilst running tests on it.

Is there any particular logs I should look at that might help?

EDIT- thanks for your reply Eric, I didn’t see it whilst posting this one. I’m leaving it up and monitoring it now to see if anything happens. The iptables do indeed show that there are no rules currently.

If the issue happens again I will check with the datacenter to see if there are any network issues.

Here is the last lines of dmesg, I can’t see any errors but I’m not an expert.
md: bind
md: running:
raid1: raid set md0 active with 2 out of 2 mirrors
md: … autorun DONE.
md: Autodetecting RAID arrays.
md: autorun …
md: … autorun DONE.
kjournald starting. Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
SELinux: Disabled at runtime.
SELinux: Unregistering netfilter hooks
type=1404 audit(1297886090.631:2): selinux=0 auid=4294967295 ses=4294967295
input: PC Speaker as /class/input/input1
sd 0:0:0:0: Attached scsi generic sg0 type 0
sd 1:0:0:0: Attached scsi generic sg1 type 0
shpchp: Standard Hot Plug PCI Controller Driver version: 0.4
ACPI: PCI Interrupt 0000:00:1f.3[C] -> GSI 18 (level, low) -> IRQ 225
r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
ACPI: PCI Interrupt 0000:06:00.0[A] -> GSI 16 (level, low) -> IRQ 50
PCI: Setting latency timer of device 0000:06:00.0 to 64
eth0: RTL8168c/8111c at 0xffffc2000000e000, 6c:62:6d:a0:77:56, XID 1c4000c0 IRQ 82
ACPI: PCI Interrupt 0000:02:00.1[B] -> GSI 17 (level, low) -> IRQ 169
PCI: Setting latency timer of device 0000:02:00.1 to 64
floppy0: no floppy controllers found
lp: driver loaded but no devices found
ACPI: Power Button (FF) [PWRF]
ACPI: Power Button (CM) [PWRB]
ACPI: Mapper loaded
dell-wmi: No known WMI GUID found
md: Autodetecting RAID arrays.
md: autorun …
md: … autorun DONE.
device-mapper: multipath: version 1.0.5 loaded
loop: loaded (max 8 devices)
EXT3 FS on md4, internal journal
kjournald starting. Commit interval 5 seconds
EXT3 FS on md1, internal journal
EXT3-fs: mounted filesystem with ordered data mode.
kjournald starting. Commit interval 5 seconds
EXT3 FS on md2, internal journal
EXT3-fs: mounted filesystem with ordered data mode.
kjournald starting. Commit interval 5 seconds
EXT3 FS on md3, internal journal
EXT3-fs: mounted filesystem with ordered data mode.
Adding 8391928k swap on /dev/md0. Priority:-1 extents:1 across:8391928k
NET: Registered protocol family 10
lo: Disabled Privacy Extensions
IPv6 over IPv4 tunneling driver
ip6_tables: © 2000-2006 Netfilter Core Team
r8169: eth0: link up
r8169: eth0: link up
eth0: no IPv6 routers present
ip_tables: © 2000-2006 Netfilter Core Team
Netfilter messages via NETLINK v0.30.
ip_conntrack version 2.4 (8192 buckets, 65536 max) - 304 bytes per conntrack

4

Yeah, I don’t see any errors in that dmesg output.

So, asking your provider if they know of any issues might be a good next step (in addition to trying to ping your various IP addresses next time it’s not working).

-Eric

5

I’ve found the source of the problem but not sure why it’s happening just yet. When I assign the extra IPs with the information the Datacenter provide me it all goes down after restarting network and the IPs disappear from the system.

It sounds like a problem their end so I’ll get in touch with them.

6

The problem has been solved. It was my fault I was mixing up some of the IP values when entering them. That’ll teach me to work all night on something… :slight_smile: Thanks for your help.

7

Great, I’m glad you got it working! Thanks for the update.

Have a good one!

-Eric