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IP Alias default outgoing interface?

 
 
agentbullvi@gmail.com
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      12-26-2005, 09:09 PM
Hello,

I've run into this situation on several versions of RedHat linuxes..
Fedora, and now Cent -- I don't know if it happens on others.

I am currently running CentOS 4.2
- of the 4 network interfaces in the server, only eth0 is
comfigured/active
- All of the ip addresses on eth0 are "public" IP addresses, not NAT
private addresses
- While IP tables is installed on the system I've disabled it for
purposes of diagnosing this issue
- I have no advanced routing at all, a simple static route to a
default gateway.
- This is my kernel: 2.6.9-22.0.1.ELsmp

Here is my situation, I have a NIC with a n IP address, and several IP
aliases; example:
eth0: - 10.10.10.10
eth0:1 - 10.10.10.11
eth0:2 - 10.10.10.12
eth0:3 - 10.10.10.13
eth0:4 - 10.10.10.14
eth0:5 - 10.10.10.15

(my actual IP addresses are public IP addresses)

When making outgoing connections the system always uses the very last
IP alias as the connection IP. This is bad news for a mailserver, since
the main IP is tyipcally what you have reverse DNS'd. I need the
default outgoing IP address to be the NIC's IP address, not the IP
alias address.

What I've been doing is moving the IP I need as the default IP to the
last IP alias, but this screws up applications that look up just eth0.

Anyone else run into this, and if you have, how have you dealt with it?

Thank you,

--B

 
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Jacob Bunk Nielsen
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      12-27-2005, 10:09 AM
(E-Mail Removed) writes:

> Anyone else run into this, and if you have, how have you dealt with it?


I don't have a solution for you, but what does 'route -n' tell you?

--
Jacob
 
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Davide Bianchi
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      12-27-2005, 10:16 AM
On 2005-12-26, (E-Mail Removed) <(E-Mail Removed)> wrote:
> Here is my situation, I have a NIC with a n IP address, and several IP
> aliases; example:
> eth0: - 10.10.10.10
> eth0:1 - 10.10.10.11
> eth0:2 - 10.10.10.12
> eth0:3 - 10.10.10.13
> eth0:4 - 10.10.10.14
> eth0:5 - 10.10.10.15


If all the IPs are in the same subnet (as your choices implies), you could
use ONE ip on the eth0 and a subnet mask to catch all of them. This will
solve your problem by having ONE ip on the nic.

Davide

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I admit that X is the second worst windowing system in the world, but all
the others I've used are tied for first. --Paul Tomblin
 
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agentbullvi@gmail.com
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      12-28-2005, 06:25 PM


It tells me.... I have a default route..

Did you mean something specific.

 
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