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I'm using dhcp on both client and server on Linux machine
I would like to "force" some dhcp options from the dhcp server to the dhcp client
Specifically I'd like the client to set into his lease database the following options: dhcp-renewal-time and dhcp-rebinding-time So far I was not able to have the client adding such options to his lease database. Reading the dhcp-options man page I noticed the following paragraph:


From: man 5 dhcp-options

Some of the options documented here are automatically generated by the DHCP server or by clients, and cannot be config‐ ured by the user. The value of such an option can be used in the configuration file of the receiving DHCP protocol agent (server or client), for example in conditional expressions. However, the value of the option cannot be used in the configuration file of the sending agent, because the value is determined only after the configuration file has been processed. In the following documentation, such options will be shown as "not user configurable"

Both options I'm interested in are marked as "not user configurable", but my understanding of the above paragraph is that, depending on the option, only one of the side (client or server) can configure the parameter. In this specific scenario I would imagine that the server can communicate the client the values for renewal and rebinding, not the other way around. Is this correct? Someone out there succeeded in configuring such options?

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I've always understood that the renewal time is 50% of the lease time and is calculated when the lease is handed out. The client will attempt to contact the original DHCP server when this times out.

The Rebinding time is 87.5% of the lease time and again is calculated when the lease is handed out. If it times out the client will attempt to contact any DHCP server to renew it's IP address.

These timers are reset whenever a new lease is obtained. There is a discussion of this in the TCP/IP Guide

The only way you can affect these values is to change the lease time.

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You are right, but I'm trying to reproduce a scenario with a device that is sending to my client the above options explicitly: ie in my lease db I have: option dhcp-renewal-time 1800; option dhcp-rebinding-time 3150; –  sergico Jul 25 '12 at 13:08
    
@sergico: You can't do that because they're not user configurable. –  Iain Jul 25 '12 at 16:47
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