Home / server / Questions / 427047
Accepted
Frederik
Asked: 2012-09-14 02:51:39 +0800 CST

Enabling one interface breaks connectivity on another

  • 772

I got a server with 2 NIC's.

One is the external interface, that has a public IP.

When only that interface is up, I can ping it fine from our internal network.

When I enable the second interface with the internal IP address on, I cannot ping the external IP anymore from the internal network. I can however ping it from a server on another internet connection.

I have been dealing with this for quite some time, and I really cant figure out why it won't work..

I have rebooted the server numerous times, without effect.

Interface configurations are as follows:

ifcfg-eth0 (External)

DEVICE="eth0"
BOOTPROTO="static"
HWADDR="00:24:81:82:D2:26"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="d8c860fb-eab3-410c-a137-b100fa77ca51"
NETMASK="255.255.255.240"
IPADDR="7x.6x.1xx.1xx"

ifcfg-eth2 (Internal)

DEVICE="eth2"
BOOTPROTO="static"
HWADDR="00:23:7D:9C:CA:A7"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="d544ec14-80fa-4765-bec4-e616b0b86bb8"
NETMASK="255.255.255.0"
IPADDR="192.168.11.15"

/etc/sysconfig/network

NETWORKING=yes
HOSTNAME=HOSTNAME
GATEWAY=7x.6x.1xx.1xx

Routing table

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
7x.6x.1xx.1xx   *               255.255.255.240 U     0      0        0 eth0
192.168.11.0    *               255.255.255.0   U     0      0        0 eth2
link-local      *               255.255.0.0     U     1002   0        0 eth0
link-local      *               255.255.0.0     U     1004   0        0 eth2
default         ip07x06x1xx1xx. 0.0.0.0         UG    0      0        0 eth0

I am pinging from a computer in the 192.168.11.0 network. There is a hardware firewall between them, but the logs show nothing of interest.

They are connected to the same switch on the 192.168.11.0 network.

centos

1 Answers

  1. Best Answer

    And in general, modify your config to disable the NetworkManager control with: NM_CONTROLLED="no". Also disable the NetworkManager service if it's running...

    See if that helps first.

    Outside of that, what is the source of your ping? 192.168.11.x?

    • 1