[tor-relays] DynDNS and TOR bridge

Wed Mar 6 12:52:46 UTC 2013

I get the whole system and certainly for a middle or exit relay the ip address is the one to work with. 

For a birdge however I thought differently, because I thought that if someone gets my bridge adress then he will put it into his config file. Now if my ip adress changes, again that entry in the config file is invalid, even though my bridge is running. Or simple, since bridges are not dynamically updated I thought using DynDNS would make sense.

------- Original message -------
> From: Matt Joyce <toradmin at mttjocy.co.uk>
> To: tor-relays at lists.torproject.org
> Sent: 6.3.'13,  1:15
> 
> Unfortunately the directories do use IP addresses not hostnames, this
> does mean there is a small time lag between a change and the new IP
> becoming available to clients but that would not in fact be eliminated
> by DynDNS either, it's quite easy to see why when you think of the
> process that has to happen for a DynDNS update to reach an end user:
> 
>  1. Your local update software has to notice that your IP has changed,
>     generally a check happens ever few minutes (Around 5 mins mostly).
>  2. Update client pushes update to DynDNS servers over HTTP.
>  3. Scripting on the DynDNS server runs an update on the authoritative
>     DNS server which then updates the Master zonefile.
>  4. Secondary authoritative DNS servers run their regular update job to
>     pull changes from the master.
>  5. DNS caches around the world need to have their TTL timer run to 0,
>     until this happens they continue to serve the old data from the caches.
> 
> Only after 5 happens do the caching servers finally stop using the old
> information and request the data from the Master and Slave DNS servers,
> someone here can perhaps explain the process of a similar update with
> the bridge directory but I suspect the timeframe for it to happen could
> potentially be similar the main relay directory is almost certainly
> slower because the consensus is only built once per hour but bridges are
> listed separately.
> 
> The unfortunate fact is a change of IP address is disruptive to clients
> there is no obvious means to eliminate the problem either, this is why
> dynamic IP addresses are not ideal for any kind of server.  Any system
> attempting to maintain connectivity for a dynamic server always has to
> make tradeoffs the main one between bandwidth/CPU and downtime for each
> change event because the faster clients poll for updated information the
> harder the hit on the central server.  If you really want to avoid this
> one option is to minimize the frequency of the change by keeping your
> internet connected your IP will only change if you disconnect from the
> internet and stop sending DHCP renews to your ISP server, depending how
> sticky your address is it can be possible to keep an IP for a long time,
> my dynamic IP was assigned after the last time I had an internet outage
> back in October last year for example and has been renewed every hour since.
> 
> As for a complete solution the only option is to get a static IP address
> for that you need to contact your service provider most can provide the
> service on request typically for a nominal charge (£1-2 per month per
> address or similar).  Almost certainly the provider will be able to do
> it if they also provide business services sometimes pure residential
> providers can't or more accurately refuse to do so (Any DHCP server
> capable of managing effectively the pool of a normal ISP can have
> reserved addresses configured if the provider wished to provide the
> service) mine is unfortunately in this camp which is why I get left with
> the keep it as long as possible option.  I can't help to wonder as to
> their logic half the time it hardly conserves addresses when it changes
> at most once or twice a year anyway, or they could choose to get paid
> every month for the one off act of having some trainee tech write a line
> of text in a config file once.
> 
> On 06/03/13 05:09, Sina Eetezadi wrote:
>> So I did that. To my surprise Vidalia shows still my IP adress, as the
>> URL to be shared. Does that mean also the other distribution mechanisms
>> use my ip?
>> Since it is constantly changing that would kinda contradict the use of
>> DynDNS. My idea was precisely to use DynDNS so that users who have my
>> bridge in their config can use it for a long time.
>>
>> Thank you for clarification.
>>
>>
>>> Simply download DynDNS or No-IP, make sure it works, and set your
>>> subdomain/domain-name in the torrc file.
>>>
>>>
>>> On Tue, Mar 5, 2013 at 12:31 PM, Sina Eetezadi <sina.eetezadi at gmail.com
>>> <mailto:sina.eetezadi at gmail.com>> wrote:
>>>
>>>
>>>     Hi,
>>>
>>>     I have a bridge running and since my ISP is changing my IP at least
>>>     daily, I thought it might be a good idea to set my DynDNS in the
>>>     torrc file.
>>>     Is it a good idea? How do I set that?
>>>
>>>     Thank you.
>>>
>>>     Sina
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>>>
>>>
>>>
>>>
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> 
> 