[BlueOnyx:13857] Re: IP address change for email (Tom)

[Chuck Tetlow]

No.  If you're using one IP for the main IP on the server, and different IPs for the domains - you need to tell your router where to send those different IPs when you change the main one on the server.

Lets explain:

If the server's main IP is 1.1.1.1, and all the domains are using 192.168.0.0 addresses - there is a router somewhere that knows to send packets for 192.168.x.x to the 1.1.1.1 address.

But if you change the main server's IP to 2.2.2.2, those packets for the domains on the 192.168.0.0 addresses won't reach the server.  The router is still sending them to 1.1.1.1, and obviously the server won't respond to it.  So you have to change the router so the 192.168.x.x packets will go to the new 2.2.2.2 IP (new IP on the server).

The only exception to this is - if the server's main IP and the domains are all in the same sub-network.  So if you own five IPs starting with 172.16.32.225 255.255.255.248 and going through 172.16.32.230 - one of them has to be on the router as the default gateway (usually the 225 or the 230 IP).  The other five are yours to use.  If you put one on the server as the main server IP (say 172.16.32.225 for example), you could use the other four (226, 227, 228, 229) for the domains on the BlueOnyx server.  In that case - you could change the server's mail IP from the .225 to the .228 for example - and wouldn't have to change your router configuration.

BUT!  You do have to wait a bit after the change - for data to start flowing again.  It has to do with the ARP tables, and could potentially take as long as four or five minutes.  Or if you have access to the router - either flush its ARP table, or restart the router.  Either of those will get data flowing again right away after changing the main server IP.  Or simply wait a few minutes for the ARP table entries to time out and get replaced.

We've had some problems with a BX user's password getting out, and the account was being misused to send out tons of crap.  Google blacklisted the server's main IP.  After finding and suspending that user account, I changed the main server's IP to another in the same subnet.  And since I have access to the Cisco router - I used the "clear arp" command to get traffic flowing again.

So changing your IP to another in the same subnet should work - but it may take a few minutes for data to start flowing again.  Or reset your router.

Chuck

---------- Original Message -----------
From: Tom <wcstaff at webcoast.com> 
To: blueonyx at blueonyx.it 
Sent: Tue, 15 Oct 2013 21:31:48 +0000 (UTC) 
Subject: [BlueOnyx:13843] Re: IP address change for email (Tom)

> >     
> 
> >     log into a shell session   su -   enter root 
> passwordexecute   ./network_settings.sh 
> 
> >     
> 
> >       
> 
> > 
> 
> I did that and it shows the new IP address. However, all domains are now 
> unreachable. I put it back to the original IP and the doamins work again. 
> I'm assuming some dns entry changes are needed? 
> 
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> Blueonyx mailing list 
> Blueonyx at mail.blueonyx.it 
> http://mail.blueonyx.it/mailman/listinfo/blueonyx 
------- End of Original Message -------
 
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