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Background

Solution

1. Stop the Interface

   This is the first thing to do if you are to change/delete an interface. If you are to create one, skip this step.

   
   # ifconfig <interface> down
   

   This command will stop the interface. For example,

   
   # ifconfig qfe0 down
   

   will stop your qfe0 interface.

2. Unplumb the interface

   Follow this step only if you are to remove the interface.

   Simply issue a:

   
   # ifconfig <interface> unplumb
   

   to remove the interface completely.

3. Plumb the interface

   To create a new interface, first you have to plumb it:

   
   # ifconfig <interface> plumb
   
   

   For your qfe1 interface,

   
   
   # ifconfig qfe1 plumb
   

4. Configure the interface

   Several options can be set/unset when you configure an interface. By far, the most used command syntax is as follow:

   
   
   # ifconfig <interface> <ip_address> netmask <netmask>
   

   For example, to set interface qfe1 to use an IP address of 10.3.234.25 and a netmask of 255.0.0.0, write:

   
   
   # ifconfig qfe1 10.3.234.25 netmask 255.0.0.0
   

5. Start the interface

   This command will start the interface so that it can begin sending/receiving data:

   
   
   # ifconfig <interface> up
   

   Following our example, start qfe1 by issuing:

   
   # ifconfig qfe1 up
   

   Tip: You can combine the last two steps:

   
   
   # ifconfig qfe1 10.3.234.25 netmask 255.0.0.0 up
   

Note the method instructed above is NOT permanent: changes will be lost after reboot. The following Mini-How-To will address that configuration change.

1. Edit the /etc/hosts file

   Edit the /etc/hosts file and include an entry for each interface yo want to configure. Give it a different name. For example, to configure hme0 and qfe0, include:

   
   my_machine	10.1.235.34
   my_machine_qfe0 10.1.235.88
   

   There are no restrictions regarding the belonging to different networks.

2. Edit the /etc/hostname.<interface> files

   For each interface you want to change permanently, you have to include the name (as is the /etc/hosts file) of the interface:

   
   # cat /etc/hostname.hme0
   my_machine
   
   # cat /etc/hostname.qfe0
   my_machine_qfe0
   

   The next time the machine reboots it will take your changes

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