[Opensim-dev] external host name

Chris Hart Chris at codetorque.co.uk
Fri Dec 12 08:07:44 UTC 2008 

Having a bunch of region files with external.host.name instead of
123.123.123.123 IP addresses makes it easier to move regions from one
server to another in case of a server move and editing all the region
xml if you don't keep the same IP address... but whatever your choice
for hostname or IP, Cristina is spot on - we should not have
inconsistency in the code. It might break 17 things in the code right
now, but equally it might flag up more areas where improvements can be
made and lead to increased stability down the line. 

Not sure which way I lean on using hostname or IP, but given that
resolving hostnames via DNS is an extra hop, do we really want to have
to do that on each occasion? Already fighting transatlantic lag to get
from US-hosted regions to UK-hosted regions on a grid, any time saved on
looking up hostnames would be nice. Can we resolve once on region
connect and work with IP from there on in?
 

-----Original Message-----
From: opensim-dev-bounces at lists.berlios.de
[mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of Hurliman,
John
Sent: 12 December 2008 07:49
To: opensim-dev at lists.berlios.de
Subject: Re: [Opensim-dev] external host name

Resolving all hostnames to IP addresses would break virtual hosting, a
very common practice. I don't understand your earlier argument: we can't
assume DNS presence*, so we should use DNS to resolve all hostnames? Can
you clarify that?

*If you're building a virtual world in an environment where there is no
DNS service, why would you put a hostname in your config file?

John

> -----Original Message-----
> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev- 
> bounces at lists.berlios.de] On Behalf Of Melanie
> Sent: Thursday, December 11, 2008 9:31 PM
> To: opensim-dev at lists.berlios.de
> Subject: Re: [Opensim-dev] external host name
> 
> Then we should resolve all hostname fields int he LL stack, and feed
> the client IP addresses. That should still allow us flexible handling.
> Most importantly, we should not string-compare hostss. Not if (host a
> == host b) but if (resolve(host a) == resolve(host b))
> 
> Melanie
> 
> 
> Diva Canto wrote:
>> I agree. The problem is that the client doesn't understand that, and
>> this causes problems with caps urls.
>> 
>> Melanie wrote:
>>> A host name can also be an IP address. IP addresses and hostnames
are
>>> interchangable and we can't assume DNS presence. So, the field
should
>>> accept a name or IP, and resolve names, like almost everything else
on
>>> the internet does.
>>> 
>>> Melanie
>>> 
>>> 
>>> Cristina Videira Lopes wrote:
>>> 
>>>> The thing is that this can potentially create a RegionInfo data
>>>> structure with
>>>>            nRegionInfo.ExternalHostName = regionData.IPADDR;
>>>> 
>>>> This is inconsistent with certain queries on the Grid server, like
>>>> "give me all my neighbors" which may send host names.
>>>> 
>>>> So, back to the point: someone needs to decide what is it that
>>>> RegionInfo.ExternalHostName  is supposed to hold.
>>>> 
>>>> Teravus Ovares wrote:
>>>> 
>>>>> RegionUpData is my fault, and spawned from compatibility issues
>>>>> with .NET remoting and Mono remoting with complex types.  It is
>>>>> only used to notify a neighbor region that 'this region is up'
>>>>> 
>>>>> Best Regards
>>>>> 
>>>>> Teravus
>>>>> 
>>>>> On 12/11/08, Cristina Videira Lopes <lopes at ics.uci.edu> wrote:
>>>>> 
>>>>> 
>>>>>> Things are very messy right now. You can search for "sim_ip", for
>>>>>> example, which is used in chatting with the grid server, and
where
>>>>>> it is being converted to an IP address in about half of the
cases.
>>>>>> 
>>>>>> To compensate, and before I noticed this inconsistency, Homer
>>>>>> introduced another field called "sim_host", so not to mess with
>>>>>> what was already there, that is supposed to carry the external
host
>>>>>> name, but this only works up to the point in which RegionInfo
data
>>>>>> structures are created. At that point, we need to decide what to
>>>>>> place in m_externalHostName, sim_ip or sim_host. Which means
>>>>>> changes in OGS1.
>>>>>> 
>>>>>> I also noticed that there is yet another data structure called
>>>>>> RegionUpData that uses IP addresses.
>>>>>> 
>>>>>> So, messy. Someone should decide what this field is supposed to
>>>>>> be, and make it a rule.
>>>>>> 
>>>>>> Charles Krinke wrote:
>>>>>> 
>>>>>> Dear Diva:
>>>>>> 
>>>>>> You have a very good point and I would support harmonizing to
>>>>>> one notion even at the expense of breaking some things for a
while.
>>>>>> 
>>>>>> In fact, if someone can identify what some of those things are,
or
>>>>>> come up with a couple of search strings or grep expressions, I
>>>>>> would like to look at the anomalies myself.
>>>>>> 
>>>>>> +1 on external_host_name
>>>>>> 
>>>>>> Charles
>>>>>> 
>>>>>> ________________________________
>>>>>> 
>>>>>> 
>>>>>> From: Cristina Videira Lopes <lopes at ics.uci.edu>
>>>>>> To: opensim-dev at lists.berlios.de
>>>>>> Sent: Thursday, December 11, 2008 2:42:05 PM
>>>>>> Subject: [Opensim-dev] external host name
>>>>>> 
>>>>>> It turns out that a lot of problems with CAPs have to do with
>>>>>> inconsistencies surrounding the URL of the seed cap.
Specifically,
>>>>>> in some cases we're producing URLs with hostnames, other times
>>>>>> we're producing URLs with IP addresses, for example:
>>>>>> 
>>>>>> http://ucigrid03.nacs.uci.edu:9000/CAPS/4cfc94fa-09be-409b-b136-
cd
>>>>>> a2cdde0000/ vs. MailScanner has detected a possible fraud attempt
>>>>>> from "128.200.71.43:9000" claiming to be MailScanner warning:
>>>>>> numerical links are often malicious:
>>>>>> http://128.200.71.43:9000/CAPS/4cfc94fa-09be-409b-b136-
cda2cdde000
>>>>>> 0/
>>>>>> 
>>>>>> The client is not smart enough to test if this is the same host,
>>>>>> it assumes it isn't, so it decides someone's trying to game it.
>>>>>> 
>>>>>> The inconsistencies are all over the code in OpenSim, and they
>>>>>> pertain to the use of ExternalHostName in several data s!
>>>>>> tructures. In some cases, an explicit conversion to IP addresses
is
>>>>>> made.
>>>>>> 
>>>>>> We should converge to one single thing. And I believe that thing
>>>>>> should be whatever it is given in external_host_name config. Is
>>>>>> this right? However, I am a bit afraid this is going to break 17
>>>>>> different things...
>>>>>> 
>>>>>> Crista
>>>>>> 
>>>>>> _______________________________________________
>>>>>> Opensim-dev mailing list
>>>>>> Opensim-dev at lists.berlios.de
>>>>>> https://lists.berlios.de/mailman/listinfo/opensim-dev
>>>>>> ________________________________
>>>>>> 
>>>>>> 
>>>>>> 
>>>>> _______________________________________________
>>>>> Opensim-dev
>>>>> 
>>>>> 
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>>>>>> list
>>>>>> 
>>>>>> 
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>>>>> 
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