change ip address every 6 hours

[Tom Martinson]

I again strongly suggest that you rethink this course of action.  But if 
you still want to do it.  I would suggest that you read up on how ISC 
DHCP servers work, or hire a consultant.

Now once customers realize what you are doing, how are you planning on 
solving the problem when people just simply get a lease and statically 
assign their IP addresses?  When that starts to happen you will have 
some major issues.

I can not stress enough how badly things are going to go wrong if you 
take this course of action.

Tom

On 02/15/2012 03:27 AM, Yannick CHAMPS wrote:
> 1. Sorry, but what do I have to modify in the different dhcpd.conf files
> to make ip change happens ?
>
> 2. of course DDNS will update but your current IP sessions (vpn,
> download...)will terminate during the IP change operation
>
>
>
> Le 14/02/2012 22:08, Tom Martinson a écrit :
>> Two things.
>>
>> 1.  You can do this by changing having a couple of dhcp.conf files and
>> change the files from time to time.  Just do a cron entry for this.
>>
>> 2.  This will not solve your problem.  All your customer needs to do
>> is sign up for one of the free Dynamic DNS services.  Even new
>> personal home routers from makers like (Linksys, dlink, netgear, ect.
>> ) have automatic DDNS updates on it.
>>
>> Basically this is not how you want to solve this issue.  What are you
>> using to deliver service, WiMAX, DSL, Cable?  If you are using Cable
>> Modems you should just edit the modem config file to filter off
>> incoming ports that you want to block.
>>
>> Tom
>>
>> On 02/15/2012 03:00 AM, Yannick CHAMPS wrote:
>>> Our "legitimate" reason is : we want to charge subcribers for fixed ip
>>> address service.
>>> So others must have their ip addresses changed regularly.
>>>
>>> Can I have some details about external scripting you mentioned earlier ?
>>>
>>>
>>> Le 14/02/2012 21:38, Simon Hobson a écrit :
>>>> Yannick CHAMPS wrote:
>>>>
>>>>> could you kindly share a sample of dhcpd.conf which changes randomly
>>>>> subscribers ip addresses every 6 hours ?
>>>> No, because it's not supported. It is expressly against the RFCs which
>>>> require the server to try and give a client the same IP address each
>>>> time it connects - subject to it not having been given to a different
>>>> client since it last had a lease.
>>>> Bear in mind that it breaks so many things. To start with, all
>>>> sessions that a customer has open (perhaps a download that's got 5
>>>> minutes left but has been running for 2 hours) will break. That alone
>>>> is good enough reason not to do it.
>>>>
>>>> There are ways to "sort of" simulate this - but they all require
>>>> external scripting to modify the config file periodically.
>>>>
>>>>
>>>> Must admit, it's not come up for some time - the usual response is
>>>> "check the archives, it comes up regularly - and no we won't help you
>>>> break things that badly" (or something to that effect).
>>>>
>>>> Do you have a specific reason for needing to do this ? Other than a
>>>> manager telling you that he needs customers to keep changing IP
>>>> address to make it hard to run servers at home. Such an attempt is a
>>>> waste of time - there are many dynamic DNS servers out there that will
>>>> "fix" that problem.
>>>>
>>>> I think we only saw one legitimate reason in all the times this came
>>>> up. All the rest were "my manager needs me to break the network and
>>>> p**s off our customers". To the latter, the response is "go find
>>>> another job, your customers will get p**ssed off and move to a decent
>>>> ISP - and your's will go bust".
>>>>
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>>
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