Centos Networking

Centos Network interfaces examples

Static

[root@hydrogen]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 
DEVICE="eth0"
BOOTPROTO="none"
HWADDR="52:54:00:5B:C7:10"
ONBOOT="yes"
IPADDR=192.168.5.24
NETMASK=255.255.255.0
DEFROUTE=yes
[root@hydrogen]#

$ cat /etc/sysconfig/network
HOSTNAME=server.name.pri
NETWORKING=yes
NETWORKING_IPV6=yes
GATEWAY=192.168.1.10

$ cat /etc/resolv.conf 
search mydomain.co.uk mydomain.pri
nameserver 192.168.1.1

DHCP

DEVICE="eth0"
BOOTPROTO="dhcp"
ONBOOT=yes

Bonding

$ cat /etc/sysconfig/network-scripts/ifcfg-eth[0-1]
DEVICE="eth0"
HWADDR="50:E5:49:1D:75:B1"
NM_CONTROLLED="no"
ONBOOT="yes"
BOOTPROTO=none

MASTER=bond0
SLAVE=yes
USERCTL=no




DEVICE="eth1"
HWADDR="00:10:18:27:62:98"
NM_CONTROLLED="no"
ONBOOT="yes"
BOOTPROTO=none
MASTER=bond0
SLAVE=yes
USERCTL=no

$ cat /etc/sysconfig/network-scripts/ifcfg-bond0 
DEVICE=bond0
IPADDR=192.168.1.1
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
ONBOOT=yes
BOOTPROTO=none
USERCTL=no

$ cat /etc/sysconfig/network
HOSTNAME=server.name.pri
NETWORKING=yes
NETWORKING_IPV6=yes
GATEWAY=192.168.1.10

VLAN driver

This requires the 802.1q module to talk to the Cisco switch:-

# modprobe 8021q

Not tested.

Bonding with VLAN driver and bridging

No specific switch config is required for this, but the switch ports need to be trunks not access ports.

Not tested.

Appendix

Possible duplicate stuff from Redhat 5

Ethernet Bonding

The bonding driver needs to be passed some parameters in modprobe.conf.

[root@db03 network-scripts]# cat /etc/modprobe.conf
alias eth0 bnx2
alias eth2 bnx2
alias bond0 bonding
options bond0 mode=1 miimon=100 max_bonds=2
alias bond1 bonding
options bond1 mode=1 miimon=100

The mode=1 tells it to use active/passive, miimon sets the interval to check the mii interface to detect a failed link, and max_bonds sets the required number of bonding interfaces, default is 1.

[root@db03 network-scripts]# pwd
/etc/sysconfig/network-scripts
[root@gy-asp-db03 network-scripts]# cat ifcfg-bond0
DEVICE=bond0
IPADDR=192.168.206.93
NETMASK=255.255.255.0
NETWORK=192.168.206.0
ONBOOT=yes
BOOTPROTO=none
USERCTL=no

[root@db03 network-scripts]# cat ifcfg-eth0
# Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet
DEVICE=eth0
HWADDR=1C:C1:DE:07:CO:AF
BOOTPROTO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no

[root@db03 network-scripts]# cat ifcfg-eth2
# Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet
DEVICE=eth2
HWADDR=D4:85:64:68:AA:BB
BOOTPROTO=none
ONBOOT=yes
HOTPLUG=no
MASTER=bond0
SLAVE=yes
USERCTL=no

IP routing

Persistent routes can be set in /etc/sysconfig/network-scripts with a separate file for each interface:-

[root@db03 network-scripts]# cat route-bond0 
GATEWAY0=192.168.206.1
NETMASK0=255.255.255.0
ADDRESS0=192.168.205.0

#.207 network not currently in use (was for ringo)
#GATEWAY1=192.168.206.1
#NETMASK1=255.255.255.0
#ADDRESS1=192.168.207.0

This gives the following (edited) output:-

[root@db03 network-scripts]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
.....
192.168.205.0    192.168.206.1    255.255.255.0   UG    0      0        0 bond0
.....
default         192.168.201.1    0.0.0.0         UG    0      0        0 bond1
[root@db03 network-scripts]#

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