Force a DHCP release / renew on ASA from CLI

[schinatti]

Hi forum,

Is it possible to force an ASA to release and/or renew a DHCP lease?  To be clear, the ASA is a DHCP client in this case, getting its IP address from an ISP on an external interface.  I couldn't seem to find anything in the docs for this function, which seems like a pretty basic thing to want to do.  I saw some references to doing this through ADSM, but nothing from the CLI.  This is an ASA5505 running 8.2(2) if that matters. 

Thanks in advance!

[lcambron]

Hello,

There isn't currently a command for that, the only way will be by removing the "ip address dhcp" command and re-add it.

Regards,

Felipe.

[schinatti]

That's surprising ... Presumably that would be "no ip address dhcp" command from the interface level of the CLI?  Does that command specifically generate a DHCP release on the interface?  Occasionally I need to release the DHCP IP address - otherwise the ISP will not hand out a new address if I need to switch routers for some reason...

Thanks.

[lcambron]

Hello,

Yes removing and re-adding the command from the interface should generate a dhcp renew.

Regards,

Felipe.

[schinatti]

But specifically when I delete the "ip address", does that cause a DHCP release?

The scenario I'm interested in is if I'm using the ASA as a router for my ISP, but I want to switch to a different router (i.e. not the ASA).  My ISP will not provide a new DHCP address until the current one is released (or the lease expires, or you call into tech support to manually release the address).  I'd like to be able to force the ASA to release the address, but not necessarily renew it with the ASA.

Thanks in advance...

[lcambron]

Yes it should cause the release, you can enable "debug dhcpc event", issue "no ip address" on the interface and wait for the debug statement indicating that the IP has been free'd.

Regards,

Felipe.

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[Jesper Kellerstam]

Hi,

From what I know you can renew the ip address if you are using the latest version av the ASDM.

I havn't found the cli-command for renewing the ip-address though.

Cheers,
Jesper

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