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Is there an MacOS command that makes a dhcp request, and renews the old lease, drops it for a new one, or usefully reports errors or lack of response from a dhcp server?

This would both help fix networking on the machine after problems on the network without rebooting and would also be useful to diagnose wider networking problems from a mac.

I can not find any command equivalent of dhclient though obviously some component must be serving this purpose. The question is, is that component exposed to a command line interface?

I am biased to the command line for these features and may have overlooked settings panels or tools that might solve it using a gui interface.

I believe this question is at the heart of this other question: Is there an equivalent command for 'init.d/networking restart' in OS X

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Good question but is there any particular reason you're not doing this through the GUI? – John Gardeniers Nov 12 '12 at 2:17
GUI's are subjected to more changes and the results are harder to capture where as the commands could even be an – John Hall Nov 13 '12 at 6:13
up vote 5 down vote accepted

To renew the lease:

sudo ipconfig set <interface> DHCP

Usually interface is en0 or en1.

To see all the gory details, run sudo ipconfig setverbose 1 before you run the above, then tail /var/log/system.log. After you're done, remember to run sudo ipconfig setverbose 0 to turn it off again.

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Usually happens to me when I lock my Mac and log in to my session back again I lost DNS config or resolv.conf doesn't work. So this command saved me the task of disconnecting and reconnecting back to the network to fix it. Thanks. – mdiianni Oct 2 '14 at 11:19

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