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I know that you can make a virtual network interface in Windows (see here), and in Linux it is also pretty easy with ip-aliases, but does something similar exist for Mac OS X? I've been looking for loopback adapters, virtual interfaces and couldn't find a good solution.

You can create a new interface in the networking panel, based on an existing interface, but it will not act as a real fully functional interface (if the original interface is inactive, then the derived one is also inactive).

This scenario is needed when working in a completely disconnected situation. Even then, it makes sense to have networking capabilities when running servers in a VMWare installation. Those virtual machines can be reached by their IP address, but not by their DNS name, even if I run a DNS server in one of those virtual machines. By configuring an interface to use the virtual DNS server, I thought I could test some DNS scenario's. Unfortunately, no interface is resolving DNS names if none of them are inactive...

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on your same topic, more or less… –  Yar Mar 27 '09 at 1:56

11 Answers 11

The loopback adapter is always up.

ifconfig lo0 alias will add an alias IP to the loopback adapter

ifconfig lo0 -alias will remove it

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This is correct for creating an alias, but to my knowledge you cannot define a DNS Server linked to the loopback adapter, so it will not work in my scenario as described above. –  Hans Doggen Nov 22 '09 at 11:11
This is not a true virtual network interface. –  AdamIerymenko Jul 21 '14 at 18:29

Replying in particular to:


This can be achieved using a Tun/Tap device as suggested by psv141, and manipulating the /Library/Preferences/SystemConfiguration/preferences.plist file to add a NetworkService based on either a tun or tap interface. Mac OS X will not allow the creation of a NetworkService based on a virtual network interface, but one can directly manipulate the preferences.plist file to add the NetworkService by hand. Basically you would open the preferences.plist file in Xcode (or edit the XML directly, but Xcode is likely to be more fool-proof), and copy the configuration from an existing Ethernet interface. The place to create the new NetworkService is under "NetworkServices", and if your Mac has an Ethernet device the NetworkService profile will also be under this property entry. The Ethernet entry can be copied pretty much verbatim, the only fields you would actually be changing are:

  • UUID
  • UserDefinedName
  • IPv4 configuration and set the interface to your tun or tap device (i.e. tun0 or tap0).
  • DNS server if needed.

Then you would also manipulate the particular Location you want this NetworkService for (remember Mac OS X can configure all network interfaces dependent on your "Location"). The default location UUID can be obtained in the root of the PropertyList as the key "CurrentSet". After figuring out which location (or set) you want, expand the Set property, and add entries under Global/IPv4/ServiceOrder with the UUID of the new NetworkService. Also under the Set property you need to expand the Service property and add the UUID here as a dictionary with one String entry with key __LINK__ and value as the UUID (use the other interfaces as an example).

After you have modified your preferences.plist file, just reboot, and the NetworkService will be available under SystemPreferences->Network. Note that we have mimicked an Ethernet device so Mac OS X layer of networking will note that "a cable is unplugged" and will not let you activate the interface through the GUI. However, since the underlying device is a tun/tap device and it has an IP address, the interface will become active and the proper routing will be added at the BSD level.

As a reference this is used to do special routing magic.

In case you got this far and are having trouble, you have to create the tun/tap device by opening one of the devices under /dev/. You can use any program to do this, but I'm a fan of good-old-fashioned C myself:

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
int main()
   int fd = open("/dev/tun0", O_RDONLY);
   if (fd < 0)
      printf("Failed to open tun/tap device. Are you root? Are the drivers installed?\n");
      return -1;
   while (1)
   return 0;
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Will this solution allow you to turn on "Internet Sharing" to bridge the tap interface to the ethernet or airport interface? –  Sukima Jan 11 '12 at 20:41
I've tested it and yes, it does. I was able to share my OpenVPN tun0 device (from my Ethernet connection) over my WiFi using this method. –  thenickdude Apr 2 '13 at 9:36
Note: I tried this to a vmnet (VMware virtual network adapter) and I can't get it active with an IP. (For uses with tun/tap devices as discussed this solution really works) –  TCB13 Sep 2 '13 at 1:33
Is there a way around the "a cable is unplugged" issue? I followed the instructions and they work great, however with the "cable unplugged" OS X believes that the host is offline and trying navigate to any site in my browser tells me there is no internet connection. –  Dan Ramos Jun 18 at 15:09

It's possible to use TUN/TAP device.

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User yar made a similar suggestion through a blog post. I've looked at it, but I didn't test it out, because of lack of time and I don't have the need anymore. Nevertheless thanks. –  Hans Doggen Nov 19 '09 at 22:39

A few others seemed to hint at this, but the following demonstrates using ifconfig to create a vlan and test DNS on the virtual interface (using minidns) on OS X 10.9.5:

$ sw_vers -productVersion
$ sudo ifconfig vlan169 create && echo vlan169 created
vlan169 created
$ sudo ifconfig vlan169 inet netmask && echo vlan169 configured
vlan169 configured
$ sudo ./ &
[1] 35125
$ miniDNS :: * 60 IN A

$ dig @ +short
Request: ->
Request: ->
$ sudo kill 35125
[1]+  Exit 143                sudo ./
$ sudo ifconfig vlan169 destroy && echo vlan169 destroyed
vlan169 destroyed
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What do you mean by



I can make a new interface, base it on an already existing one, then disable the existing one and the new one still works. Making a second interface does however not create a real interface (when you check with ifconfig), it will just assign a second IP to the already existing one (however, this one can be DHCP while the first one is hard coded for example).

So did I understand you right, that you want to create an interface, not bound to any real interface? How would this interface then be used? E.g. if you disconnect all WLAN and pull all network cables, where would this interface send traffic to, if you send traffic to it? Maybe your question is a bit unclear, it might help a lot if rephrase it, so it's clear what you are actually trying to do with this "virtual interface" once you have it.

As you mentioned "alias IP" in your question, this would mean an alias interface. But an alias interface is always bound to a real interface. The difference is in Linux such an interface really IS an interface (e.g. an alias interface for eth0 could be eth1), while on Mac, no real interface is created, instead a virtual interface is created, that can configured and used independently, but it is still the same interface physically and thus no new named interface is generated (you just have two interfaces, that are both in fact en0, but both can be enabled/disabled and configured independently).

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Take a look at this tutorial, it's for FreeBSD but also applies to OS X.

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i have resorted to running PFSense, a BSD based router/firewall to achieve this goal….

why? because OS X Server gets so FREAKY without a Static IP…

so after wrestling with it for DAYS to make NAT and DHCP and firewall and …

I'm trying this is parallels…

will let ya know how it goes...

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Go to Network Preferences.

At the bottom of the list of network adapters, click the + icons

Select the existing interface that you want to arp (say Ethernet 1), and give the Service Name that you want for the new port (say Ethernet 1.1) then press create.

Now you have the new virtual interface in the gui and can manage IP addresses etc it in the normal way.

ifconfig -a will confirm that you have multiple IPs on the interface, and these will still be there when you reboot.

Its a Mac. Don't fight it, do it the easy way.

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As noted in the original question, this doesn't achieve the desired effect of a virtual interface isolated from a physical interface. The command you described simply aliases the same physical interface with a second IP configuration. –  bleater Feb 19 '12 at 23:58

Here's a good guide:

Basically you select a network adapter in the Networks pane of system preferences, then click the gear to "Duplicate Service". After the service is duplicated, you manually assign an IP in one of the private address ranges. Then ping it to make sure ;)

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In regards to @bmasterswizzle's BRILLIANT answer - more specifically - to @DanRamos' question about how to force the new interface's link-state to "up".. I use this script, of whose origin I cannot recall, but which works fabulously (in coordination with @bmasterswizzles "Mona Lisa" of answers)...


[[ "$UID" -ne "0" ]] && echo "You must be root. Goodbye..." && exit 1
echo "starting"
exec 4<>/dev/tap0
ifconfig tap0
ifconfig tap0 up
ping -c1
echo "ending"
export PS1="tap interface>"
dd of=/dev/null <&4 & # continuously reads from buffer and dumps to null

I am NOT quite sure I understand the alteration to the prompt at the end, or...


but WHATEVER. it works. link light🚦: green✅. loves it💚.

enter image description here

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ifconfig interfacename create will create a virtual interface,

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Could you provide an example for that? If I try that, it does not work and has never worked as far as I know. –  Mecki Sep 17 '08 at 21:21
I can confirm, it will not work –  Hans Doggen Sep 17 '08 at 21:25
ifconfig vlan0 create as documented in the ifconfig man page "create Create the specified network pseudo-device. If the interface is given without a unit number, try to create a new device with an arbitrary unit number." –  Brian Mitchell Sep 18 '08 at 14:48
It will not work as the vlan0 above cannot be made active (status) and so it will not receive any packets... –  Hans Doggen Sep 18 '08 at 18:48
Well your question related a virtual interface, without any indication about what you wanted to do with it, which is specifically what I answered. This feature is for vlans, you can do something like ifconfig vlan0 vlan sometag vlandev en0 ipconfig set vlan0 DHCP If a vlan is your goal. –  Brian Mitchell Sep 19 '08 at 18:16

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