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guntbert
Asked: 2014-11-09 10:45:21 +0800 CST

How can I (from CLI) assign multiple IP addresses to one interface?

  • 772

On my server I want to assign several IP addresses to one NIC, but without using the deprecated ifconfig or the obsolete "alias" notation (like eth0:0) in /etc/network/interfaces because in IP Aliasing (on www.kernel.org) you can read

IP-aliases are an obsolete way to manage multiple IP-addresses/masks per interface

networking

3 Answers

  1. Best Answer

    1. If you need an additional IP address just for the moment you can add it to any interface on your machine with

       sudo ip address add <ip-address>/<prefix-length> dev <interface>

      for instance

       sudo ip address add 172.16.100.17/24 dev eth0

      would add 172.16.100.17 using a 24 bit network prefix to the list of addresses configured for your eth0.

      You can check the result with

      ip address show eth0

      and you can delete this address again with

      sudo ip address del 172.16.100.17/24 dev eth0

      Of course these changes are lost when you reboot your machine.

    2. To make the additional addresses permanent you can edit the file /etc/network/interfaces by adding as many stanzas of the form

      iface eth0 static
    address 172.16.100.17/24

      so that it looks like

      iface eth0 inet dhcp

iface eth0 inet static
    address 172.16.100.17/24

iface eth0 inet static
    address 172.16.24.11/24

      You can even keep the dhcp for the primary address.

      To activate these settings without a reboot use ifdown/ifup like

      sudo ifdown eth0 && sudo ifup eth0

      It is essential to put those two commands into one line if you are remoting into the server because the first one will drop your connection! Given in this way the ssh-session will survive.

    • 56

  2. With the new toolkit, it is as easy as with the old to add new ip addresses:

    ip addr add 192.168.1.1/24 dev eth0

    When looking with ip addr show again, you see the second ip address assigned to the interface:

    2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.100/24 brd 192.168.0.255 scope global eth0
    inet 192.168.1.1/24 scope global eth0
    inet6 fe80::223:54ff:fe45:f307/64 scope link
       valid_lft forever preferred_lft forever

    Remove that ip address with:

    ip addr del 192.168.1.1/24 dev eth0

    The iproute2 suite:

    The iproute2 suite is the communication suite for interprocess communication beween the kernel and the user space via the netlink protocol. It should replace the whole standard network tools. Here is what they replace:

    • ifconfig --> ip addr and ip link
    • route --> ip route
    • arp --> ip neigh
    • iptunnel --> ip tunnel
    • ipmaddr --> ip maddr
    • netstat --> ss
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  3. One way is:

    sudo ip addr add 192.168.0.2/24 dev eth1
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