[CentOS] Multiple Internet facing Nics - Gateway issue

Wed Jul 1 20:30:45 UTC 2009
Doug Coats <dcoatshca at gmail.com>

Thanks for your responses.  I have tried some of the configurations that you
have mentioned but not all of them.  I will try the others tonight when the
server is less active.  In the meantime I will read the links you sent.

Thanks again.  This is starting to drive me crazy.

On Wed, Jul 1, 2009 at 3:07 PM, Alexander Dalloz
<ad+lists at uni-x.org<ad%2Blists at uni-x.org>
> wrote:

> Doug Coats schrieb:
>  > I have a server with 4 nics.  Two are using different internet
> connections,
> > both with static IP's, and two are connected to our private network.
> >
> > The two internet facing nics seem to be battling over the gateway
> > designation.  Which ever I designate as the gateway the other stops
> > responding to incoming traffic.  I need both to listen to inbound
> traffic.
> > One for our main web page and the other for another web server.  I found
> > some information of Iproute2 but that did not seem to solve my issues.
> >
> > Here are the config files:
> >
> > ifcfg-eth2
> > DEVICE=eth2
> > BOOTPROTO=static
> > HWADDR=00:24:E8:52:92:8E
> > ONBOOT=yes
> > IPADDR=xx.yy.51.45
> > NETMASK=255.255.255.252
> > GATEWAY=xx.yy.51.46
> >
> > ifcfg-eth3
> > DEVICE=eth3
> > BOOTPROTO=static
> > HWADDR=00:24:E8:52:92:90
> > ONBOOT=yes
> > IPADDR=aa.bb.166.2
> > NETMASK=255.255.255.224
> > GATEWAY=aa.bb.166.1
> >
> > network
> > NETWORKING=yes
> > NETWORKING_IPV6=no
> > HOSTNAME=heritage01
> > GATEWAY=xx.yy.51.46
> > GATEWAYDEV=eth2
> >
> > rt_tables
> > #
> > # reserved values
> > #
> > 255     local
> > 254     main
> > 253     default
> > 0       unspec
> > #
> > # local
> > #
> > #1      inr.ruhep
> > 200 Cable
> > 201 T1
> > iproute2 routes
> > ip route add xx.yy.51.44/30 dev eth2 src xx.yy.51.46 table Cable
> > ip route add default via xx.yy.51.46
> > ip route add xx.yy.51.44/30 dev eth2 src xx.yy.51.46
> > ip route add default via xx.yy.51.46
> > ip rule add from xx.yy.51.46 table Cable
> > ip route add aa.bb.166.0/27 dev eth3 src aa.bb.165.2 table T1
> > ip route add default via aa.bb.166.1
> > ip route add aa.bb.166.0/27 dev eth3 src aa.bb.166.2
> > ip rule add from aa.bb.166.2 table T1
> > ip route flush cache
> >
> > Other people seem to be using this configuration successfully but I seem
> to
> > be missing something important.
> >
> > Any help is greatly appreciated!!!!!!!  Thanks!
>
> The GATEWAY parameter within the ifcfg-<ethX> configuration files tries
> to set the default gateway. There can be just 1 default gateway for a
> system. So, the interface which comes up first will set the route and
> the other has no effect.
>
> Remove the GATEWAY entry from all ifcfg-<ethX> files and place the
> GATEWAY parameter into /etc/sysconfig/network only.
>
> Running different networks you must can set additional routings by
> route-<ethX> configuration files inside /etc/sysconfig/network-scripts/.
>
> Given your default gateway is set as xx.yy.51.46 for the network
> configured on eth2, you set to use a gateway aa.bb.166.1 for other
> destinations by
>
> ip route add targetnet/CIDR via aa.bb.166.1 dev eth3
>
> Please see
>
>
> http://www.centos.org/docs/5/html/5.1/Deployment_Guide/s1-networkscripts-static-routes.html
>
> You multiple uplink topic is documented in this howto
>
> http://lartc.org/howto/lartc.rpdb.multiple-links.html
>
>
> Alexander
>
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