[Linux-users] 2 IP's on the same network card

[James McDonald]

Dirk Moolman wrote:
> Ok, I found it - and it is actually so simple:
>
> http://learnlinux.tsf.org.za/courses/build/net-admin/ch01s10.html
>
> To plumb your device, you may run the command:
>
> ifconfig eth0 192.168.0.1 netmask 255.255.255.0
> ifconfig eth0:1 172.16.5.1 netmask 255.255.255.0
>
>
> "These commands would plumb the interface. Notice that the eth0:1 gives
> the interface the second IP address. Using any number in place of the
> '1' would also work."
>
>  
>   
Another lower level way of doing the same thing is using ip

ip addr

2: eth0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo+AF8-fast qlen 1000
    link/ether 00:08:74:3b:59:58 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.6/24 brd 192.168.1.255 scope global eth0
    inet6 fe80::208:74ff:fe3b:5958/64 scope link
       valid+AF8-lft forever preferred+AF8-lft forever

ip addr add 192.168.1.220 dev eth0
   2: eth0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo+AF8-fast
qlen 1000
    link/ether 00:08:74:3b:59:58 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.6/24 brd 192.168.1.255 scope global eth0
    inet 192.168.1.220/32 scope global eth0
    inet6 fe80::208:74ff:fe3b:5958/64 scope link
       valid+AF8-lft forever preferred+AF8-lft forever

To delete
ip addr del 192.168.1.220 dev eth0

However the secondary address will not show up using ifconfig
ifconfig
eth0      Link encap:Ethernet  HWaddr 00:08:74:3B:59:58
          inet addr:192.168.1.6  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::208:74ff:fe3b:5958/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:4377 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1777 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1151555 (1.0 MiB)  TX bytes:145992 (142.5 KiB)
          Interrupt:11 Base address:0x2c00