configuring a secondary (additional) IP address

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Level 3

955 points

configuring a secondary (additional) IP address

I'd like to add a secondary IP address to one of my network locations, in order to enable a 137.121.2/24 LAN. On MSWin, there's an easy interface to do this (either as a secondary address or as a list of additional addresses depending on whether you're on a laptop or not). On Mac OS X, I can't seem to find how to do it. I've either forgotten how I managed under Linux, or things don't work exactly the same under OS X. I've managed to create a VLAN, but that still doesn't allow me to connect to one of the other machines that have an address in the cited range.

I'm sure I'm missing something, but what?

MBP 13" 2.4Ghz 6/250Gb, Mac OS X (10.6.5), 12" PillowBook 1.0Ghz 0.7/ext-80Gb; PB15" RIP; dual G5@1.8Ghz

Posted on Jan 4, 2011 5:45 AM

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Answer 1

Aug 10, 2017 11:24 PM in response to RJV Bertin

Yeah, it's pretty easy. Open the System Preferences, go to Networking, then click the Plus sign under the left bar. Choose the interface, give a name to the adapter configuration you're creating, then press OK and deal with it as you would like to. Click Apply when you're done, and enjoy. Your adapter now has two IP addresses.

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Answer 2

BobHarris

Level 9

56,813 points

Jan 4, 2011 6:33 AM in response to RJV Bertin

System Preferences -> Network
Select your networking interface
Using the "Gear" icon at the bottom of the list select "Duplicate"
Now configure the duplicate interface the way you desire.

My iMac has 2 IP addresses. I can address my iMac using either IP address.

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Answer 3

RJV Bertin Author

Level 3

955 points

Jan 4, 2011 7:24 AM in response to BobHarris

Thanks ... now I have 2 addresses listed on my en0 interface, but I still can't even ping the WinXP VM I have running on the same machine inside VirtualBox (which has both a secondary 137.121.2 address configured on its [bridged] internet Adapter 1 and one on its [NAT] Adapter 2).
I'm a bit flabbergasted: I never had any problems setting this kind of thing up before :S

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Answer 4

RJV Bertin Author

Level 3

955 points

Jan 17, 2011 1:37 AM in response to RJV Bertin

Bump ...

I still manage to connect to my own secondary IP address only ... even the secondary IP address (on the same subnet) that I configured in my VirtualBox win32 VM remains inaccessible.
Help?

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Answer 5

BobHarris

Level 9

56,813 points

Jan 17, 2011 6:16 AM in response to RJV Bertin

I'm wondering if you have a router for the 137.121.2/24 subnet, and are your network interfaces which are using 137.121.2/24 addresses specifying the router servicing the 137.121.2/24 subnet?

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Answer 6

RJV Bertin Author

Level 3

955 points

Jan 17, 2011 7:18 AM in response to BobHarris

A router isn't needed for a local /24 (255.255.255.0) net. At least, I've always been able to do without. But, I've tried both with and without a router specification, doesn't make a difference.

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