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I work on a server (BSD), which for security reasons is set up to allow connections only from a particular IP address. This is problematic because I have a dynamically assigned IP address on my Mac laptop, and that's not something that I can change. For now, my workaround is to tunnel through a colleague's desktop computer (Ubuntu), which does have the correct IP address. He is the sysadmin for the server, but is a very inexperienced sysadmin with a lot on his plate, so finding other server-side solutions may not happen quickly. He has told me that he can set multiple IP addresses for his own machine, which is what I would like to do on my Mac. The one time I tried to set my IP address manually with ifconfig, it screwed up my VPN connection, which I need to maintain.

So my question is, how can I manually set an IP address for a terminal session on my Mac in such a way that it doesn't interfere with other network activity, which may require a different IP address?

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The only way I've done this successfully, is with a virtual machine. I give the VM a static IP address, and with a small enough guest OS, your memory usage won't be too insane. – user3463 Aug 23 '12 at 17:51

IP addresses must be unique on the network; your machine and your colleague's machine cannot have the same IP addrs (hacking/spoofing tricks notwithstanding).

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You are capable of having 1 IP per interface. Your ethernet might vary from your AP, however, both can only have one at a time.

The setting on the server is only a firewall setting and easy to fix, just get the sysadmin to let you change it or be persistent until he changes it himself.

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