do ISPs keep track of end-user IP changes within thier network?

R. Scott Evans nanog at
Thu Dec 12 16:07:28 UTC 2013

I'm no lawyer but in the U.S., 18 USC 2703 appears to indicate this data 
must be kept for at least 180 days.


On 12/12/13 06:34, Sam Moats wrote:
> I'm not sure about the current state of the industry it's been a while
> since I was responsible for an access network. In the past we would keep
> radius logs for about 4 months, these would include the username,IP
> address and yes (to date myself) the caller id of the customer at the time.
> Sam Moats
> On 2013-12-12 03:49, Ray Wong wrote:
>> been a while, but seems like lately it's more a question of how long.
>> ISPs
>> can be in position where they need to, but as things have consolidated,
>> seems like they'd really like to forget it as soon as they can. If you've
>> got a specific case in mind, likely best to find a direct contact and
>> get a
>> response about policy, even if it has to be off-record. The big ones
>> (like
>> one I likely shouldn't mention by name unless they do as I don't work for
>> them) definitely do, at least long enough to handle DMCA requests and
>> other
>> legal obligations.
>> -R>
>> On Wed, Dec 11, 2013 at 9:36 PM, Mikael Abrahamsson
>> <swmike at>wrote:
>>> On Wed, 11 Dec 2013, Carlos Kamtha wrote:
>>>  just a general curiousity question. it's been a long time since ive
>>>> worked at an ISP.
>>>> back then it was non-expiring DHCP leases and in some cases static
>>>> IP for
>>>> all.. (yes it was long ago..)
>>>> Any feedback would be greatly appreciated..
>>> Yes, it's very common to keep track of what user account/line had
>>> what IP
>>> at what time.
>>> --
>>> Mikael Abrahamsson    email: swmike at

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