Centos – Problem Assigning Static IP to CentOS Server

centosdhcpnetworkingstatic-ip

We have a sandbox server running CentOS that we run inside our office. Our ISP has assigned us a block of 5 static IPs. We now want to assign it a static IP.

DEVICE=eth0
BOOTPROTO=none # have also tried "static" here
HWADDR=00:13:72:*:*:*
ONBOOT=yes
TYPE=Ethernet
NETMASK=255.255.255.0
IPADDR=173.*.*.161
GATEWAY=10.1.10.1

/etc/resolv.cnf is also set with the appropriate name servers from our ISP.

When I ifdown eth0 then ifup eth0 I get…

SIOCADDRT: Network is unreachable

When I switch to DCHP, the machine has an IP assigned and there are no connection problems.

Any ideas?

Best Answer

The IP Address and gateway are in 2 totally different networks. So change your gateway or IP address to an address within the same network.

NETMASK=255.255.255.0
IPADDR=173.*.*.161    <--
GATEWAY=10.1.10.1     <--

Related Solutions

Debian – Static virtual IP in debian 6.0.4

Alias/virtual interfaces are deprecated and should not be used. You should instead use iproute2 to add additional addresses to the actual interface:

iface eth0 inet static
    address 192.168.1.151
    gateway 192.168.1.1
    netmask 255.255.255.0
    network 192.168.1.0
    broadcast 192.168.1.255
    up ip addr add 192.168.1.175/24 dev eth0

To check the configured IP addresses use ip addr show.

Assigning the same IP to multiple machines will cause neither to work correctly though.

Redhat – Centos multiple NICs routing issue

For any network device which is not my default gateway, I usually set the default route flag to no:

DEFROUTE="no"

This seems to work without any issues for my servers with multiple network interfaces. If you then restart your network service or interfaces, you should be able to check the routes to see that this is actually working:

/sbin/route -n

Hopefully this helps.

Best Answer

Related Solutions

Debian – Static virtual IP in debian 6.0.4

Redhat – Centos multiple NICs routing issue

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