dhcpcd-discuss

On 16/03/17 16:57, Shahid Mahmood wrote:
> On Thu, Mar 16, 2017 at 10:38 AM, Roy Marples <roy@xxxxxxxxxxxx
> <mailto:roy@xxxxxxxxxxxx>> wrote:
> 
>     On 16/03/2017 13:48, Shahid Mahmood wrote:
>     >     Why would you want to configure it anyway?
>     >
>     > We are seeing a situation where upon a RENEW, the server sends a
>     > different IP address than requested.
>     >
>     >
>     >     You'll get the new config
>     >     eventually (when T1 expires or the carrier goes down/up), reconfigure
>     >     accept just gets you it faster when pushed from the server.
>     >     Because the protocol requires a nonce, it's pretty secure.
> 
>     Can you explain more why this is a problem for you given the above?
>     With DHCPv6, you'll just get the new address faster and the existing
>     address just won't get refreshed and the kernel will remove it when it
>     expires.
> 
> Basically the application requires persistent IP sessions at run time.
> An IP address change would disrupt those sessions, leading to a longer
> recovery path.

Ah, now we get to the real issue.
So dhcpcd has the "leasetime" option, which is only used for IPv4
addresses currently.

We could re-use this to send an empty address with the valid and
preferred lifetimes set to the "leasetime" option - so you effectively
request the address for that amount of time. The specification allows an
all-ones lifetime to represent infinity.

Would that satisfy your need?

Roy