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Old 12-18-2007, 05:56 AM   #1
david_s26
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IP Address conflict issue - Sorry posted in wrong place originally


(I am sorry I posted this in the wrong sub forum earlier - Never try posting with two windows open if you lack brain power like I do!!)

Right shoot me down if this is too much of a silly question,

I have just taken over admin of 5 servers one of which is a linux box (soon to be 2, then 3...hopefully but anyway) There is a slight ip address conflict on the system the exteranl facing ip addys of the system go from xxx.xxx.xxx.2 - 6.
The linux box being 5, I have noticed that one of the win machines keeps dropping the terminal services connections over the internet, so I looked into it and found that the linux both has a an alias, I think it is called, that listens on it's ip; but it is not a big error, i.e. neither machines comlain of the conflict ever 10 or 20 seconds or so as they do on a LAN when ips conflict, in fact the win box only has 4 mentions of this conflict in it's event log for the last year.

linux box ifconfig:

eth0 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx
inet addr:xxx.xxx.xxx.5 Bcast:xxx.xxx.xxx.31 Mask:xxx.xxx.xxx.224
inet6 addr: xxxxxxxxxxxxxxxxxxxxxxxxxxxx Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4366215 errors:0 dropped:0 overruns:0 frame:0
TX packets:7164214 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:512638318 (488.8 MiB) TX bytes:728437252 (694.6 MiB)
Interrupt:169

eth0:1 Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx(same as above!)
inet addr:xxx.xxx.xxx.6 Bcast:xxx.xxx.xxx. Mask:xxx.xxx.xxx..0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:169

I have three questions really: I am told that this has been done for a reason, can anyone think of a reason?

Also I have tried to stop the eth0:1 and it brings the whole network down, after which I needed to reboot, is there a way just to stop this alias. I would like to do it with little or no down time as this machine hosts a web shop.

I cannot find a script that starts this eth0:1, but it appeared again after the reboot, there is not ifcfg-eth0:1 file, or mention of it in the ifcfg-eth0 file. The only places in etc where that ip is mentioned is /etc/addrpool /etc/ips /etc/nameserverips and httpd conf.

I would be very grateful if someone could offer me a little advicer in this situation.
 
Old 12-18-2007, 06:28 AM   #2
stzein
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you could quickly test the effect of changing/disabling the ip address with the commands
ifconfig eth0:1 down
to disable it.
ifconfig eth0:1 xxx.xxx.xxx.xxx
to set the desired ip address.

To permanently change your network settings the easiest is to use the tools provided with your distro (you didn't mention which?)
 
Old 12-18-2007, 06:36 AM   #3
david_s26
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many thanks for your reply I tried;
ifconfig eth0:1 down

And it brought the whole network interface down, the website stopped (even though it's ip address is the xxx.xxx.xxx.5 not .6) I am just a little confused as to what is going on.

I am using Red Hat Enterprise rel 4, but it is a remote setup, so all I have is ssh terminal, no interface.
 
Old 12-18-2007, 06:48 AM   #4
david_s26
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Could I make a slight update, is it significant that the ifconfig output is only the first three lines in the case of the problem one, it does not contain any of the packet information collisions etc. I just set up a Red Hat test machine and made an eth0:1 alias and the ifconfig output is in full.

Does this mean anything to anyone?
 
Old 12-18-2007, 07:00 AM   #5
stzein
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I'm not sure what's going on with the network, but if you're on a linux machine it might help to connect with 'ssh -Y' instead of just ssh, this gives you the possibility to run graphical programs (if there are any on the server, and ssh is configured to allow it).

Maybe to find out why the network is configured as it is we need some more information. What does the server run? where is it positioned in your network? Are those ip adresses all external adresses (reachable from the internet)?
 
Old 12-18-2007, 07:59 AM   #6
david_s26
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Hello, Many thanks for staying with me on this one...

The ip addresses in question are external ones, we have a five server rack on which we have a main IIS (arrgghh!) website xxx.2, xxx.3 mail, xxx.4 sql server, xxx.5 has our shop and forums; apache, mysql and xxx.6 which is a MS Svr2004 box suppose to hold backups and for a secure ftp link, user to upload content, save them having access to our main web server.

The servers are behind some kind of firewall, that we don't administer that, but the admin of all of the boxes is our responsibilty.

I think that my predessesor set the alias up on the linux box to listen to the xxx.6 ip address but I do not know why. And I cannot see whwere it is set up, it is comes back on when the box restarts, but I cannot see where it is defined, much less what exactly it does.
 
Old 12-18-2007, 08:42 AM   #7
stzein
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Quote:
I tried;
ifconfig eth0:1 down

And it brought the whole network interface down, the website stopped
The website stopped, but was your ssh connection broken? If not, then the .6 address is probably needed because the dns name for your forum or shop points to it (to check type 'nslookup shop/forums.website.com').
In this case you need to contact the company responsible for your dns records, or depending on the situation you could move around the ip addresses of several servers.
 
Old 12-18-2007, 11:18 AM   #8
david_s26
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I risked another try at ifconfig eth0:1 down and the result was the same, although it did point me in the direction of some more dtails of my system I think may aid anyone who is trying to help me:

There is another alias on the system xxx.7, and that is wher nslookup says may websites are located ifconfig out put below:

eth0 Link encap:Ethernet HWaddr XX:00:XX:00:00:CA
inet addr:xxx.xxx.xxx.5 Bcast:xxx.xxx.xxx.31 Mask:xxx.xxx.xxx.224
inet6 addr: fe80::215:c5ff:fef7:fca/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5435710 errors:0 dropped:0 overruns:0 frame:0
TX packets:9063186 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:629420258 (600.2 MiB) TX bytes:3240655597 (3.0 GiB)
Interrupt:169

eth0:1 Link encap:Ethernet HWaddr XX:00:XX:00:00:CA
inet addr:xxx.xxx.xxx.6 Bcast:xxx.xxx.xxx.255 Mask:xxx.xxx.xxx.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:169

eth0:2 Link encap:Ethernet HWaddr XX:00:XX:00:00:CA
inet addr:xxx.xxx.xxx.7 Bcast:xxx.xxx.xxx.255 Mask:xxx.xxx.xxx.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:169

Is it significant that the netmask is different?

But anyway on with the story...

ifconfig eth0:1 down caused both eth0:1 and eth0:2 to go away, My ssh stayed connected because eth0 stayed up, but like I say them websites both went down. (as I said nslookup says that xxx.7 is where both the shop and forum are pointed.)

So some ideas are what I am after...why would the system be set up this way?
Am I correct to assume that this is what is causing the problem with the win box on xxx.6?
It look like I need to keep the alias for xxx.7, but how do I get rid of the xxx.6 alias without it bringing the website down?
 
Old 12-18-2007, 06:41 PM   #9
stzein
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Have you tried changing the address?
for example:
Code:
ifconfig eth0:1 xxx.xxx.xxx.11
if something is wrong just do
Code:
ifconfig eth0:1 xxx.xxx.xxx.6
and everything is back as it was.

The different netmask prabably doesn't make any difference in your situation.

to qoute myself:
Quote:
if you're on a linux machine it might help to connect with 'ssh -Y' instead of just ssh, this gives you the possibility to run graphical programs
did you try this?
 
  


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