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*SOLVED* arpsend: x.x.x.x is detected on another computer [message #14857] Thu, 12 July 2007 03:55 Go to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
Hi, I am facing a problem with ip conflict, here is the error message.

[root@nat ~]# vzctl restart 653
Restarting VE
Stopping VE ...
VE was stopped
VE is unmounted
Starting VE ...
VE is mounted
Adding IP address(es): 192.168.6.53
arpsend: 192.168.6.53 is detected on another computer : 00:17:e0:27:ad:1a
vps-net_add WARNING: arpsend -c 1 -w 1 -D -e 192.168.6.53 eth0 FAILED
Setting CPU units: 1000
Configure meminfo: 49152
VE start in progress...
[root@nat ~]#

My Environment is :

Host OS: CentOS5
OpenVZ Kernel: 2.6.18-8.1.4.el5.028stab035.1 #1 SMP
No of NICs: 2
eth0 connected to internet with public IP
eth1 connected to lan with private IP

I would be pleased supply further information.
Please help me.

Ganesh

[Updated on: Fri, 13 July 2007 13:46] by Moderator

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Re: arpsend: x.x.x.x is detected on another computer [message #14860 is a reply to message #14857] Thu, 12 July 2007 04:42 Go to previous messageGo to next message
Vasily Tarasov is currently offline  Vasily Tarasov
Messages: 1345
Registered: January 2006
Senior Member
Hello,

you assign an IP address 192.168.6.53 to your VE. But somebody else in your network already use this IP address. The MAC address of this "bad guy" is 00:17:e0:27:ad:1a.

Sometimes people assign VE the same IP address that HN has. It is not right and leds to the error message you have indicated. Probably this is your case...

HTH,
Vasily.

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Re: arpsend: x.x.x.x is detected on another computer [message #14862 is a reply to message #14860] Thu, 12 July 2007 05:47 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
Hi Vasily,

Thank you for your reply. I verified the network no body has the IP of same. I am very sure of it.

I removed the network jacks and tried starting vps, same error.

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Re: arpsend: x.x.x.x is detected on another computer [message #14868 is a reply to message #14862] Thu, 12 July 2007 07:21 Go to previous messageGo to next message
Vasily Tarasov is currently offline  Vasily Tarasov
Messages: 1345
Registered: January 2006
Senior Member
I still think, that somebody uses this IP address Wink

Please, do the following command on HN when VE is stopped:
# ping 192.168.6.53
I'm pretty sure, that you'll be able to ping this node Wink

Vasily.

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Re: arpsend: x.x.x.x is detected on another computer [message #14881 is a reply to message #14868] Thu, 12 July 2007 11:31 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
[root@nat ~]# vzctl start 653
Starting VE ...
VE is mounted
Adding IP address(es): 192.168.6.53
arpsend: 192.168.6.53 is detected on another computer : 00:17:e0:27:ad:1a
vps-net_add WARNING: arpsend -c 1 -w 1 -D -e 192.168.6.53 eth0 FAILED
Setting CPU units: 1000
Configure meminfo: 49152
VE start in progress...
[root@nat ~]# ping 192.168.6.53
PING 192.168.6.53 (192.168.6.53) 56(84) bytes of data.
64 bytes from 192.168.6.53: icmp_seq=1 ttl=64 time=0.103 ms
64 bytes from 192.168.6.53: icmp_seq=2 ttl=64 time=0.087 ms
64 bytes from 192.168.6.53: icmp_seq=3 ttl=64 time=0.041 ms
64 bytes from 192.168.6.53: icmp_seq=4 ttl=64 time=0.027 ms
64 bytes from 192.168.6.53: icmp_seq=5 ttl=64 time=0.078 ms
64 bytes from 192.168.6.53: icmp_seq=6 ttl=64 time=0.025 ms
64 bytes from 192.168.6.53: icmp_seq=7 ttl=64 time=0.027 ms

--- 192.168.6.53 ping statistics ---
7 packets transmitted, 7 received, 0% packet loss, time 5997ms
rtt min/avg/max/mdev = 0.025/0.055/0.103/0.031 ms
[root@nat ~]# vzctl stop 653
Stopping VE ...
VE was stopped
VE is unmounted
[root@nat ~]# ping 192.168.6.53
PING 192.168.6.53 (192.168.6.53) 56(84) bytes of data.
From 192.168.6.1 icmp_seq=2 Destination Host Unreachable
From 192.168.6.1 icmp_seq=3 Destination Host Unreachable
From 192.168.6.1 icmp_seq=4 Destination Host Unreachable
From 192.168.6.1 icmp_seq=6 Destination Host Unreachable
From 192.168.6.1 icmp_seq=7 Destination Host Unreachable
From 192.168.6.1 icmp_seq=8 Destination Host Unreachable

--- 192.168.6.53 ping statistics ---
8 packets transmitted, 0 received, +6 errors, 100% packet loss, time 6997ms
, pipe 3
[root@nat ~]#

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Re: arpsend: x.x.x.x is detected on another computer [message #14885 is a reply to message #14881] Thu, 12 July 2007 14:17 Go to previous messageGo to next message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
If you have a router on your network, there is a possibility that it has proxy arp turned on - It is responding with it's mac address for networks that it does not consider local on your ethernet lan segment.

http://en.wikipedia.org/wiki/Proxy_ARP

My virtual servers do exactly the same (I have 192.168 addresses locally and a set of public ip addresses that get port forwarded to my ve's)

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Re: arpsend: x.x.x.x is detected on another computer [message #14898 is a reply to message #14885] Thu, 12 July 2007 17:38 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
How did you fixed the issue?

Please let me know your way of hanlding it.

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Re: arpsend: x.x.x.x is detected on another computer [message #14904 is a reply to message #14898] Thu, 12 July 2007 19:10 Go to previous messageGo to next message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
I chose to ignore it. It does not impair the way openVZ works plus I had no control over the router.
The message is purely a warning and is there for protection for duplicate IP's. If you have complete control of the IP's on your LAN segment, I wouldn't worry about it - just be aware that you lose that protection and be sure you don't configure 2 VE's with the same IP Smile

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Re: arpsend: x.x.x.x is detected on another computer [message #14907 is a reply to message #14904] Thu, 12 July 2007 22:59 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
Due to this error, I dont have internet access to my vps.
Some body please suggest me.

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Re: arpsend: x.x.x.x is detected on another computer [message #14912 is a reply to message #14907] Fri, 13 July 2007 08:17 Go to previous messageGo to next message
Vasily Tarasov is currently offline  Vasily Tarasov
Messages: 1345
Registered: January 2006
Senior Member
Please, try to do the following:

1) stop the VE in question
2) arping -I eth0 192.168.6.53
3) arping -I eth1 192.168.6.53

And post the output here.

Thanks!

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Re: arpsend: x.x.x.x is detected on another computer [message #14913 is a reply to message #14907] Fri, 13 July 2007 08:44 Go to previous messageGo to next message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
Do you have the correct NAT and forwarding options set ?

I use :-
-A POSTROUTING -s 192.168.1.0/255.255.255.0 -o eth0 -j SNAT --to-source <public IP>

If nothing else on your network has that IP (demonstrated by your ping) then it's a nat/routing issue that is preventing your ve's from accessing the internet.

Also, I went to the trouble of looking the MAC address up

MAC Address
Prefix Vendor
0017E0 Cisco Systems

It looks like your cisco router is doing as I suggested and proxy arping.

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Re: arpsend: x.x.x.x is detected on another computer [message #14914 is a reply to message #14912] Fri, 13 July 2007 08:45 Go to previous messageGo to next message
rickb is currently offline  rickb
Messages: 368
Registered: October 2006
Senior Member
I have the same problem on one of my networks, where I do not admin the router. Same situation as sappsys.

Is 00:17:e0:27:ad:1a the mac of your router? If so, I would conclusively its the same issue. If 00:17:e0:27:ad:1a is not your router, check that host and see waht IPs it has assigned to itself.

-------------
Common Terms I post with: http://wiki.openvz.org/Category:Definitions

UBC. Learn it, love it, live it: http://wiki.openvz.org/Proc/user_beancounters

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Re: arpsend: x.x.x.x is detected on another computer [message #14917 is a reply to message #14912] Fri, 13 July 2007 11:18 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
[root@nat ~]# vzctl stop 653
Stopping VE ...
VE was stopped
VE is unmounted
[root@nat ~]# arping -I eth0 192.168.6.53
ARPING 192.168.6.53 from 59.162.229.214 eth0
Unicast reply from 192.168.6.53 [00:17:E0:27:AD:1A] 29.720ms
Unicast reply from 192.168.6.53 [00:17:E0:27:AD:1A] 27.646ms
Unicast reply from 192.168.6.53 [00:17:E0:27:AD:1A] 27.861ms
Unicast reply from 192.168.6.53 [00:17:E0:27:AD:1A] 27.587ms
Unicast reply from 192.168.6.53 [00:17:E0:27:AD:1A] 27.771ms
Unicast reply from 192.168.6.53 [00:17:E0:27:AD:1A] 27.753ms
Sent 6 probes (1 broadcast(s))
Received 6 response(s)
[root@nat ~]# arping -I eth1 192.168.6.53
ARPING 192.168.6.53 from 192.168.1.3 eth1



Sent 313 probes (313 broadcast(s))
Received 0 response(s)
[root@nat ~]#

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Re: arpsend: x.x.x.x is detected on another computer [message #14918 is a reply to message #14917] Fri, 13 July 2007 11:24 Go to previous messageGo to next message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
For some reason my last reply didn't follow the thread down...
Just incase it was missed.

Do you have the correct NAT and forwarding options set ?

I use :-
-A POSTROUTING -s 192.168.1.0/255.255.255.0 -o eth0 -j SNAT --to-source <public IP>

If nothing else on your network has that IP (demonstrated by your ping) then it's a nat/routing issue that is preventing your ve's from accessing the internet.

Also, I went to the trouble of looking the MAC address up

MAC Address
Prefix Vendor
0017E0 Cisco Systems

It looks like your cisco router is doing as I suggested and proxy arping.

Also from your arp tests, it shows the arp responses are comming from your public side (The cisco Router).

[Updated on: Fri, 13 July 2007 11:26]

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Re: arpsend: x.x.x.x is detected on another computer [message #14919 is a reply to message #14913] Fri, 13 July 2007 11:25 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
[root@nat ~]# iptables -A POSTROUTING -s 192.168.1.0/255.255.255.0 -o eth0 -j SNAT --to-source 59.162.229.214
iptables: No chain/target/match by that name

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Re: arpsend: x.x.x.x is detected on another computer [message #14920 is a reply to message #14919] Fri, 13 July 2007 11:31 Go to previous messageGo to next message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
iptables -t nat A POSTROUTING -s 192.168.6.0/255.255.255.0 -o eth0 -j SNAT --to-source 59.162.229.214

You missed the -t nat and your subnet is 192.168.6.0/24 mine was 192.168.1.0/24

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Re: arpsend: x.x.x.x is detected on another computer [message #14921 is a reply to message #14920] Fri, 13 July 2007 12:37 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
[root@nat ~]# iptables -t nat -A POSTROUTING -s 192.168.6.0/255.255.255.0 -o eth0 -j SNAT --to-source 59.162.229.214
[root@nat ~]# vzctl enter 653
entered into VE 653
[root@nat /]# ping google.com
ping: unknown host google.com
[root@nat /]# exit
logout

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Re: arpsend: x.x.x.x is detected on another computer [message #14922 is a reply to message #14921] Fri, 13 July 2007 12:44 Go to previous messageGo to next message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
You should always try pinging an ip address first...
do you have resolv.conf set up in the VE ?

ping 66.102.9.99

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Re: arpsend: x.x.x.x is detected on another computer [message #14923 is a reply to message #14922] Fri, 13 July 2007 12:52 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
Hi sappsys,

Thank you for your precious time.

[root@nat ~]# ping 66.102.9.99
PING 66.102.9.99 (66.102.9.99) 56(84) bytes of data.
64 bytes from 66.102.9.99: icmp_seq=1 ttl=242 time=485 ms
64 bytes from 66.102.9.99: icmp_seq=2 ttl=242 time=489 ms
64 bytes from 66.102.9.99: icmp_seq=3 ttl=242 time=493 ms
64 bytes from 66.102.9.99: icmp_seq=4 ttl=242 time=478 ms

--- 66.102.9.99 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 2999ms
rtt min/avg/max/mdev = 478.418/486.701/493.942/5.764 ms
[root@nat ~]# vzctl enter 653
entered into VE 653
[root@ns /]# cat /etc/resolv.conf
nameserver 202.54.29.5
[root@ns /]# ping 66.102.9.99
PING 66.102.9.99 (66.102.9.99) 56(84) bytes of data.

--- 66.102.9.99 ping statistics ---
38 packets transmitted, 0 received, 100% packet loss, time 36989ms

[root@ns /]#

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Re: arpsend: x.x.x.x is detected on another computer [message #14924 is a reply to message #14923] Fri, 13 July 2007 13:11 Go to previous messageGo to next message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
In the host node

[root@OpenVZ init.d]# sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 1

check forwarding is set to 1

if it isn't...

sysctl -w net.ipv4.ip_forward=1

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Re: arpsend: x.x.x.x is detected on another computer [message #14927 is a reply to message #14924] Fri, 13 July 2007 13:22 Go to previous messageGo to next message
ganesh35 is currently offline  ganesh35
Messages: 11
Registered: December 2006
Location: Bangalore, India
Junior Member
[root@nat ~]# sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 0
[root@nat ~]#
[root@nat ~]# sysctl -w net.ipv4.ip_forward=1
net.ipv4.ip_forward = 1
[root@nat ~]# vzctl enter 653
entered into VE 653
[root@ns /]# ping google.com
PING google.com (72.14.207.99) 56(84) bytes of data.
64 bytes from eh-in-f99.google.com (72.14.207.99): icmp_seq=0 ttl=245 time=415 ms
64 bytes from eh-in-f99.google.com (72.14.207.99): icmp_seq=1 ttl=245 time=414 ms

--- google.com ping statistics ---
3 packets transmitted, 2 received, 33% packet loss, time 2001ms
rtt min/avg/max/mdev = 414.480/415.091/415.702/0.611 ms, pipe 2
[root@ns /]# exit
logout

exited from VE 653
[root@nat ~]# vzctl restart 653
Restarting VE
Stopping VE ...
VE was stopped
VE is unmounted
Starting VE ...
VE is mounted
Adding IP address(es): 192.168.6.53
arpsend: 192.168.6.53 is detected on another computer : 00:17:e0:27:ad:1a
vps-net_add WARNING: arpsend -c 1 -w 1 -D -e 192.168.6.53 eth0 FAILED
Setting CPU units: 1000
Configure meminfo: 49152
Set hostname: ns
File resolv.conf was modified
VE start in progress...
[root@nat ~]#

Thats great of you.
I could browse from the vps, I will treat ip conflict as a minor warning.

Thank you

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Re: arpsend: x.x.x.x is detected on another computer [message #14928 is a reply to message #14927] Fri, 13 July 2007 13:25 Go to previous message
sappsys is currently offline  sappsys
Messages: 8
Registered: July 2007
Junior Member
Fantastic Smile

Glad to help Smile

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