Table of Contents
Sometimes a server needs more than one ip address on the same network card, we call this binding ip addresses.
Linux can also activate multiple network cards behind the same ip address, this is called bonding.
This chapter will teach you how to configure binding and bonding on the most common Linux distributions.
To bind more than one ip address to the same interface, use ifcfg-eth0:0, where the last zero can be anything else. Only two directives are required in the files.
[root@rhel6 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0:0 DEVICE="eth0:0" IPADDR="192.168.1.133" [root@rhel6 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0:1 DEVICE="eth0:0" IPADDR="192.168.1.142"
To activate a virtual network interface, use ifup, to deactivate it, use ifdown.
[root@rhel6 ~]# ifup eth0:0
[root@rhel6 ~]# ifconfig | grep 'inet '
inet addr:192.168.1.99 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:192.168.1.133 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:127.0.0.1 Mask:255.0.0.0
[root@rhel6 ~]# ifup eth0:1
[root@rhel6 ~]# ifconfig | grep 'inet '
inet addr:192.168.1.99 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:192.168.1.133 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:192.168.1.142 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:127.0.0.1 Mask:255.0.0.0Use ping from another computer to check the activation, or use ifconfig like in this screenshot.
[root@rhel6 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 08:00:27:DD:0D:5C
inet addr:192.168.1.99 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fedd:d5c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1259 errors:0 dropped:0 overruns:0 frame:0
TX packets:545 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:115260 (112.5 KiB) TX bytes:84293 (82.3 KiB)
eth0:0 Link encap:Ethernet HWaddr 08:00:27:DD:0D:5C
inet addr:192.168.1.133 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
eth0:1 Link encap:Ethernet HWaddr 08:00:27:DD:0D:5C
inet addr:192.168.1.142 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1The configuration of multiple ip addresses on the same network card is done in /etc/network/interfaces by adding eth0:x devices. Adding the netmask is mandatory.
debian5:~# cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary network interface iface eth0 inet static address 192.168.1.34 network 192.168.1.0 netmask 255.255.255.0 gateway 192.168.1.1 auto eth0 auto eth0:0 iface eth0:0 inet static address 192.168.1.233 netmask 255.255.255.0 auto eth0:1 iface eth0:1 inet static address 192.168.1.242 netmask 255.255.255.0
Use ping from another computer to check the activation, or use ifconfig like in this screenshot.
debian5:~# ifconfig | grep 'inet '
inet addr:192.168.1.34 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:192.168.1.233 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:192.168.1.242 Bcast:192.168.1.255 Mask:255.255.255.0
inet addr:127.0.0.1 Mask:255.0.0.0We start with ifconfig -a to get a list of all the network cards on our system.
[root@rhel6 network-scripts]# ifconfig -a | grep Ethernet eth0 Link encap:Ethernet HWaddr 08:00:27:DD:0D:5C eth1 Link encap:Ethernet HWaddr 08:00:27:DA:C1:49 eth2 Link encap:Ethernet HWaddr 08:00:27:40:03:3B
In this demo we decide to bond eth1 and eth2.
We will name our bond bond0 and add this entry to modprobe so the kernel can load the bonding module when we bring the interface up.
[root@rhel6 network-scripts]# cat /etc/modprobe.d/bonding.conf alias bond0 bonding
Then we create /etc/sysconfig/network-scripts/ifcfg-bond0 to configure our bond0 interface.
[root@rhel6 network-scripts]# pwd /etc/sysconfig/network-scripts [root@rhel6 network-scripts]# cat ifcfg-bond0 DEVICE=bond0 IPADDR=192.168.1.199 NETMASK=255.255.255.0 ONBOOT=yes BOOTPROTO=none USERCTL=no
Next we create two files, one for each network card that we will use as slave in bond0.
[root@rhel6 network-scripts]# cat ifcfg-eth1 DEVICE=eth1 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no [root@rhel6 network-scripts]# cat ifcfg-eth2 DEVICE=eth2 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no
Finally we bring the interface up with ifup bond0.
[root@rhel6 network-scripts]# ifup bond0
[root@rhel6 network-scripts]# ifconfig bond0
bond0 Link encap:Ethernet HWaddr 08:00:27:DA:C1:49
inet addr:192.168.1.199 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:feda:c149/64 Scope:Link
UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
RX packets:251 errors:0 dropped:0 overruns:0 frame:0
TX packets:21 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:39852 (38.9 KiB) TX bytes:1070 (1.0 KiB)The bond should also be visible in /proc/net/bonding.
[root@rhel6 network-scripts]# cat /proc/net/bonding/bond0 Ethernet Channel Bonding Driver: v3.5.0 (November 4, 2008) Bonding Mode: load balancing (round-robin) MII Status: up MII Polling Interval (ms): 0 Up Delay (ms): 0 Down Delay (ms): 0 Slave Interface: eth1 MII Status: up Link Failure Count: 0 Permanent HW addr: 08:00:27:da:c1:49 Slave Interface: eth2 MII Status: up Link Failure Count: 0 Permanent HW addr: 08:00:27:40:03:3b
We start with ifconfig -a to get a list of all the network cards on our system.
debian5:~# ifconfig -a | grep Ethernet eth0 Link encap:Ethernet HWaddr 08:00:27:bb:18:a4 eth1 Link encap:Ethernet HWaddr 08:00:27:63:9a:95 eth2 Link encap:Ethernet HWaddr 08:00:27:27:a4:92
In this demo we decide to bond eth1 and eth2.
We also need to install the ifenslave package.
debian5:~# aptitude search ifenslave p ifenslave - Attach and detach slave interfaces to a bonding device p ifenslave-2.6 - Attach and detach slave interfaces to a bonding device debian5:~# aptitude install ifenslave Reading package lists... Done ...
Next we update the /etc/network/interfaces file with information about the bond0 interface.
debian5:~# tail -7 /etc/network/interfaces iface bond0 inet static address 192.168.1.42 netmask 255.255.255.0 gateway 192.168.1.1 slaves eth1 eth2 bond-mode active-backup bond_primary eth1
On older version of Debian/Ubuntu you needed to modprobe bonding, but this is no longer required. Use ifup to bring the interface up, then test that it works.
debian5:~# ifup bond0
debian5:~# ifconfig bond0
bond0 Link encap:Ethernet HWaddr 08:00:27:63:9a:95
inet addr:192.168.1.42 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fe63:9a95/64 Scope:Link
UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
RX packets:212 errors:0 dropped:0 overruns:0 frame:0
TX packets:39 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:31978 (31.2 KiB) TX bytes:6709 (6.5 KiB)The bond should also be visible in /proc/net/bonding.
debian5:~# cat /proc/net/bonding/bond0 Ethernet Channel Bonding Driver: v3.2.5 (March 21, 2008) Bonding Mode: fault-tolerance (active-backup) Primary Slave: eth1 Currently Active Slave: eth1 MII Status: up MII Polling Interval (ms): 0 Up Delay (ms): 0 Down Delay (ms): 0 Slave Interface: eth1 MII Status: up Link Failure Count: 0 Permanent HW addr: 08:00:27:63:9a:95 Slave Interface: eth2 MII Status: up Link Failure Count: 0 Permanent HW addr: 08:00:27:27:a4:92
1. Add an extra ip address to one of your network cards. Test that it works (have your neighbour ssh to it)!
2. Use ifdown to disable this extra ip address.
3. Make sure your neighbour also succeeded in binding an extra ip address before you continue.
4. Add an extra network card (or two) to your virtual machine and use the theory to bond two network cards.
1. Add an extra ip address to one of your network cards. Test that it works (have your neighbour ssh to it)!
Redhat/Fedora: add an /etc/sysconfig/network-scripts/ifcfg-ethX:X file as shown in the theory
Debian/Ubuntu: expand the /etc/network/interfaces file as shown in the theory
2. Use ifdown to disable this extra ip address.
ifdown eth0:0
3. Make sure your neighbour also succeeded in binding an extra ip address before you continue.
ping $extra_ip_neighbour or ssh $extra_ip_neighbour
4. Add an extra network card (or two) to your virtual machine and use the theory to bond two network cards.
Redhat/Fedora: add ifcfg-ethX and ifcfg-bondX files in /etc/sysconfig/network-scripts as shown in the theory and don't forget the modprobe.conf
Debian/Ubuntu: expand the /etc/network/interfaces file as shown in the theory and don't forget to install the ifenslave package