[CentOS] OT: Setting a CentOS to gateway a private IP address

James B. Byrne byrnejb at harte-lyne.ca
Tue Oct 21 19:02:36 UTC 2008

This is mildly off topic since it has more to do with TCP/IP networking
than with CentOS per se.  However, at the risk of ruffling a few feathers
I would like some advice on how to resolve the following routing problem:

dual homed host running CentOS-5.2 with
eth0 = 2xx.yyy.zzz.23
eth1 =

and a Cisco gateway at 2xx.1xx.y7y.1 with the following networks:

interface FastEthernet0/1
 description connected to EthernetLAN
 ip address secondary
 ip address secondary
 ip address secondary
 ip address secondary
 ip address 2xx.yyy.zzz.1
 ip access-group 101 in
 ip inspect FastEthernet_0_1 in
 speed 100
router rip
 version 2
 passive-interface FastEthernet0/0
 network 2xx.yyy.zzz.0
 no auto-summary
ip classless
ip route FastEthernet0/0

and with the following routes on the CentOS host:

# route
Kernel IP routing table
Destination     Gateway       Genmask         Flags Metric Ref    Use Iface   *      U     0      0        0 eth1
2xx.yyy.zzz.0   *      U     0      0        0 eth0     *        U     0      0        0 eth1
default         gw-fibrewire         UG    0      0        0 eth0
# ip route dev eth1  proto kernel  scope link  src
2xx.yyy.zzz.0/24 dev eth0  proto kernel  scope link  src 2xx.yyy.zzz.23 dev eth1  scope link
default via 2xx.yyy.zzz.1 dev eth0

The situation is this.

>From the host itself I can ping on

>From any other host on 2xx.1xx.y7y.0/24 I can ping

>From any other host on 2xx.1xx.y7y.0/24 I cannot ping

What setup steps on the CentOS host have I overlooked or what
configuration errors have I committed?

As I am a digest subscriber please use "reply all" so that I get an
immediate copy of any replies.


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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
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