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*SOLVED* arpsend: x.x.x.x is detected on another computer [message #4362]

Fri, 07 July 2006 09:46

hvdkamer
Messages: 40
Registered: July 2006

Member

There are a few similar questions in this forum, but none has an usable answer. I'm probably doing something very stupid, but what Smile

I've one public IP-adres, so I figured to use a private serie for all my guest nodes. I tried with and without and eth0:1 with IP-adress 192.168.13.1 and there is no difference.

strato:~# vzctl set 1313 --ipadd 192.168.13.2 --save
strato:~# vzctl start 1313
Starting VPS ...
VPS is mounted
Adding IP address(es): 192.168.13.2
arpsend: 192.168.13.2 is detected on another computer : 00:00:5e:00:01:02
vps-net_add WARNING: arpsend -c 1 -w 1 -D  -e 192.168.13.2 eth0 FAILED
Setting CPU units: 1000
VPS start in progress...

In another thread someone is suggesting that IP-address is used elsewhere on the network, but that is not the case. If I do an /etc/init.d/vz stop and then a ping there is no reply. If VZ is started all private IP-adresses give an reply, probably this is the function of the vznetdev module?

After entering the guestnode 1313 nothing has be done, so the above warning is serious? But I've no idea how to solve it. Any suggestions would be appreciated...

Henk van de Kamer
auteur Het Lab
http://www.hetlab.tk/

[Updated on: Tue, 11 July 2006 15:41]

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Re: arpsend: x.x.x.x is detected on another computer [message #4385 is a reply to message #4362]

Sun, 09 July 2006 11:34

dev
Messages: 1693
Registered: September 2005
Location: Moscow

Senior Member

you can try to find whom belongs this MAC address 00:00:5e:00:01:02.
This MAC reports that it uses IP address 192.168.13.2.

Most often error which is done is that VPS IP address is used in host system, because people believe they should assign it to eth0:1 or something. IP address should not be in use when assigned to VPS.
Check output of the following command in the host:
# ifconfig
# ip a l
# ip r l

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

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Re: arpsend: x.x.x.x is detected on another computer [message #4448 is a reply to message #4385]

Mon, 10 July 2006 21:45

aistis
Messages: 77
Registered: September 2005
Location: Kaunas, Lithuania

Member

In addition - it is quite frequent that switches are configured in "arp guarding"(?) mode so they report that they own the IP. That's done for security(?) reasons. So it is better that you ask your network administrator (or HSP) on that to be 100% sure.

P.S. Sorry for lame description - not the biggest networking guru Smile

Aistis Zenkevicius

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

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Re: arpsend: x.x.x.x is detected on another computer [message #4463 is a reply to message #4448]

Tue, 11 July 2006 09:03

hvdkamer
Messages: 40
Registered: July 2006

Member

aistis wrote on Mon, 10 July 2006 23:45

"arp guarding"(?) mode

I don't know if Strato is doing this. However as said, it only happens when OpenVZ is started. If it is indeed an feature of an upstream switch, it should also raise the problem without OpenVZ. Right?

strato:~# iptables -t nat -F
strato:~# iptables -F
strato:~# iptables -vxnL
Chain INPUT (policy ACCEPT 33 packets, 2988 bytes)
    pkts      bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 16 packets, 1600 bytes)
    pkts      bytes target     prot opt in     out     source               destination
strato:~# /etc/init.d/vz stop
Shutting down VPS 1313
Stopping OpenVZ: ..done
strato:~# lsmod | grep vz
vzdquota               40800  0 [permanent]
vzdev                   2624  1 vzdquota
strato:~# ping -c4 192.168.13.2
PING 192.168.13.2 (192.168.13.2) 56(84) bytes of data.

--- 192.168.13.2 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 2999ms
strato:~# /etc/init.d/vz start
Starting OpenVZ: ..done
Bringing up interface venet0: ..done
Configuring interface venet0: ..done
strato:~# lsmod | grep vz
vznetdev               17952  1
vzmon                  45020  1 vznetdev
vzdquota               40800  0 [permanent]
vzdev                   2624  3 vznetdev,vzmon,vzdquota
strato:~# ping -c4 192.168.13.2
PING 192.168.13.2 (192.168.13.2) 56(84) bytes of data.
From 85.214.0.133 icmp_seq=2 Destination Net Unreachable

--- 192.168.13.2 ping statistics ---
4 packets transmitted, 0 received, +1 errors, 100% packet loss, time 2999ms

strato:~# vzctl start 1313
Starting VPS ...
VPS is mounted
Adding IP address(es): 192.168.13.2
arpsend: 192.168.13.2 is detected on another computer : 00:00:5e:00:01:02
vps-net_add WARNING: arpsend -c 1 -w 1 -D  -e 192.168.13.2 eth0 FAILED
Setting CPU units: 1000
VPS start in progress...
strato:~# ping -c4 192.168.13.2
PING 192.168.13.2 (192.168.13.2) 56(84) bytes of data.
64 bytes from 192.168.13.2: icmp_seq=1 ttl=64 time=0.086 ms
64 bytes from 192.168.13.2: icmp_seq=2 ttl=64 time=0.014 ms
64 bytes from 192.168.13.2: icmp_seq=3 ttl=64 time=0.012 ms
64 bytes from 192.168.13.2: icmp_seq=4 ttl=64 time=0.013 ms

--- 192.168.13.2 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 2999ms
rtt min/avg/max/mdev = 0.012/0.031/0.086/0.031 ms

There is a slight difference with my start of this topic. The ping with only vz started doesn't work anymore. Probably because after much experimenting I now have networking in the VE nodes. But as you can see the aprsend is still failing. At first I thought that that was the cause of my problems. Now I think that this message is complete bogus. It would be nice if it can be resolved however, bacuase now I wasted a day before I decided that it probably doesn mean anything...

Henk van de Kamer
auteur Het Lab
http://www.hetlab.tk/

[Updated on: Tue, 11 July 2006 09:05]

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Re: arpsend: x.x.x.x is detected on another computer [message #4467 is a reply to message #4385]

Tue, 11 July 2006 09:19

hvdkamer
Messages: 40
Registered: July 2006

Member

dev wrote on Sun, 09 July 2006 13:34

Check output of the following command in the host:
# ifconfig
# ip a l
# ip r l

I have experimented with IP-adress 192.168.13.1 on eth0:1 but that didn't resolve my networking problems inside the VE. As said above, this MAC address can only come from OpenVZ itself. But may be you see something different in this output:

strato:~# /etc/init.d/vz stop
Shutting down VPS 1313
Stopping OpenVZ: ..done
strato:~# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:30:48:58:09:F0
          inet addr:85.214.61.55  Bcast:85.214.61.55  Mask:255.255.255.255
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:96934 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11622 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:30646960 (29.2 MiB)  TX bytes:3059910 (2.9 MiB)
          Interrupt:24

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

strato:~# ip a l
2: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
4: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:30:48:58:09:f0 brd ff:ff:ff:ff:ff:ff
    inet 85.214.61.55/32 brd 85.214.61.55 scope global eth0
6: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:30:48:58:09:f1 brd ff:ff:ff:ff:ff:ff
strato:~# ip r l
85.214.48.1 dev eth0  scope link
default via 85.214.48.1 dev eth0
strato:~# /etc/init.d/vz start
Starting OpenVZ: ..done
Bringing up interface venet0: ..done
Configuring interface venet0: ..done
strato:~# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:30:48:58:09:F0
          inet addr:85.214.61.55  Bcast:85.214.61.55  Mask:255.255.255.255
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:97042 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11676 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:30660432 (29.2 MiB)  TX bytes:3068042 (2.9 MiB)
          Interrupt:24

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

venet0    Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          UP BROADCAST POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

strato:~# ip a l
2: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
4: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:30:48:58:09:f0 brd ff:ff:ff:ff:ff:ff
    inet 85.214.61.55/32 brd 85.214.61.55 scope global eth0
6: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:30:48:58:09:f1 brd ff:ff:ff:ff:ff:ff
5: venet0: <BROADCAST,POINTOPOINT,NOARP,UP> mtu 1500 qdisc noqueue
    link/void
strato:~# ip r l
85.214.48.1 dev eth0  scope link
default via 85.214.48.1 dev eth0
strato:~# vzctl start 1313
Starting VPS ...
VPS is mounted
Adding IP address(es): 192.168.13.2
arpsend: 192.168.13.2 is detected on another computer : 00:00:5e:00:01:02
vps-net_add WARNING: arpsend -c 1 -w 1 -D  -e 192.168.13.2 eth0 FAILED
Setting CPU units: 1000
VPS start in progress...
strato:~# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:30:48:58:09:F0
          inet addr:85.214.61.55  Bcast:85.214.61.55  Mask:255.255.255.255
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:97115 errors:0 dropped:0 overruns:0 frame:0
          TX packets:11716 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:30671056 (29.2 MiB)  TX bytes:3075326 (2.9 MiB)
          Interrupt:24

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

venet0    Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          UP BROADCAST POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

strato:~# ip a l
2: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
4: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:30:48:58:09:f0 brd ff:ff:ff:ff:ff:ff
    inet 85.214.61.55/32 brd 85.214.61.55 scope global eth0
6: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:30:48:58:09:f1 brd ff:ff:ff:ff:ff:ff
5: venet0: <BROADCAST,POINTOPOINT,NOARP,UP> mtu 1500 qdisc noqueue
    link/void
strato:~# ip r l
192.168.13.2 dev venet0  scope link  src 85.214.61.55
85.214.48.1 dev eth0  scope link
default via 85.214.48.1 dev eth0

See also my ping answers in the previous post. An Google on the MAC address gives more hits than you would believe. And almost always in combonation with OpenVZ. So I think it is somewhere in there Smile

. As said, the FAILED arpsend is probably bogus. I now have networking, after rebooting the computer. Setting the following in Debian /etc/modules.conf doesn't work:

options ip_conntrack ip_conntrack_enable_ve0=1

I now have the following first line in my firewall/iptables script:

modprobe ip_conntrack ip_conntrack_enable_ve0=1

That only works if the module wasn't loaded before without this option! rmmod doesn't help, you NEED to reboot.

Henk van de Kamer
auteur Het Lab
http://www.hetlab.tk/

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Re: arpsend: x.x.x.x is detected on another computer [message #4472 is a reply to message #4463]

Tue, 11 July 2006 10:22

aistis
Messages: 77
Registered: September 2005
Location: Kaunas, Lithuania

Member

hvdkamer wrote on Tue, 11 July 2006 12:03

aistis wrote on Mon, 10 July 2006 23:45

"arp guarding"(?) mode

I'm almost 100% sure they are doing it. And like i mentioned in the previous post - it is best to check this with their support. Fast and painless.

Regards,

Aistis Zenkevicius

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Re: arpsend: x.x.x.x is detected on another computer [message #4483 is a reply to message #4472]

Tue, 11 July 2006 15:36

hvdkamer
Messages: 40
Registered: July 2006

Member

aistis wrote on Tue, 11 July 2006 12:22

I'm almost 100% sure they are doing it.

Sometimes I'm so stupid Smile

. It didn't occur to me that it is possible for Strato to make a server which does reply to ARP requests, but doesn't reply to ping requests.

I've booted to another Debian partition on the same machine which doesn't have any OpenVZ stuff on it. With a tcpdump I see the ARP reply and that the ping requests are going to this MAC address. But no answers of course. I hate it when they make networks this complex Crying or Very Sad

Ok, now going through the scripts to see if I can exclude eth0 in the arpsend test that OpenVZ is using. So that I can rely on the arpsend test in the future...

Thanks for the help.

Henk van de Kamer
auteur Het Lab
http://www.hetlab.tk/

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Re: arpsend: x.x.x.x is detected on another computer [message #4484 is a reply to message #4483]

Tue, 11 July 2006 15:43

dev
Messages: 1693
Registered: September 2005
Location: Moscow

Senior Member

Oh, I see. BTW, better be carefull and ask your provider for a range of private IP addresses which you can safely use. Otherwise in case of collision and poor provider network security they can cancel your contract deciding that you did harm intentionally.

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Re: arpsend: x.x.x.x is detected on another computer [message #4652 is a reply to message #4484]

Thu, 20 July 2006 15:56

Raredemon
Messages: 1
Registered: July 2006
Location: Dushanbe, Tajikistan

Junior Member

hm.. i'm also have this problem with arpsend.
Short description:
Host server:
hp01 ~ # uname -ra
Linux hp01 2.6.16-026test015 #1 SMP Thu Jul 20 19:10:00 TJT 2006 i686 Intel(R) Xeon(TM) CPU 3.00GHz GNU/Linux
with two fastethernet -
eth0 192.168.0.250/24
eth1 195.x.x.8/28

3 testing openvz system (template gentoo) - 192.168.1.[1-4]/24

Quote:

hp01 ~ # vzctl --verbose restart 814
Restarting VPS
Stopping VPS ...
VPS was stopped
Running: /usr/lib/vzctl/scripts/vps-net_del
Running: /etc/vz/814.umount
Running: /usr/sbin/vzquota stat 814 -f
Running: /usr/sbin/vzquota off 814
VPS is unmounted
Running: /usr/lib/vzctl/scripts/vps-stop
Starting VPS ...
Running: /usr/sbin/vzquota show 814
Running: /usr/sbin/vzquota on 814 -r 0 -b 1048676 -B 1153534 -i 200100 -I 220100 -e 0 -n 0 -s 0
Mounting root: /vz/root/814 /vz/private/814
Running: /etc/vz/814.mount
VPS is mounted
Adding IP address(es): 192.168.1.4
Running: /usr/lib/vzctl/scripts/vps-net_add
arpsend: 192.168.1.4 is detected on another computer : 00:0e:38:46:a8:c4
vps-net_add WARNING: arpsend -c 1 -w 1 -D -e 192.168.1.4 eth1 FAILED
Running VPS script: /etc/vz/dists/scripts/gentoo-add_ip.sh
Setting CPU units: 1000
Set hostname: test1
Running VPS script: /etc/vz/dists/scripts/gentoo-set_hostname.sh
Running VPS script: /etc/vz/dists/scripts/set_dns.sh
File resolv.conf was modified
Running: /usr/sbin/vzquota stat 814 -f
Running: vzquota setlimit 814 -b 1048576 -B 1153434 -i 200000 -I 220000 -e 0 -n 0
VPS start in progress...

i don't have any firewall installed and i can't resolve this.
2 Moderators
May be you transfer this post to russian zone of forum, because my english is very ugly Smile

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Re: arpsend: x.x.x.x is detected on another computer [message #4747 is a reply to message #4652]

Tue, 25 July 2006 08:21

hvdkamer
Messages: 40
Registered: July 2006

Member

Currently I just ignore this warning Smile

. I now know that there is a server on the Strato network who is doing this. But afterwards my VEx's work perfectly, so this check if the IP-address is in use is in my case not returning an useful answer. I could remove the eth0 form the NETDEVICES in the controlscript I suppose.

The only problem with this warning is that it got me confused for two days because of another problem. And that one was the cause of my VEx's not owrking. Because the only warning I got was the one about arpsend, it took me quite some time...

So the real question to you is this. If you ignore this warning and go into your newly started VEx. Does the network work? If not, do you use the 2.6.8 kernel?

Henk van de Kamer
auteur Het Lab
http://www.hetlab.tk/

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