[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: 20030530: Can't download IDV

Joe,

I am not web server worker, but I will tell you what I understand so
far.

Both our web server and the one you are coming from has a "name" (domain
name or host name or server name) and an "IP address" which is numbers.
For example the address 198.95.251.10 is the same as the server with
name  ns.netscape.com.

As a security measure many servers only reply to requests from systems
whose address can be matched to a name using "DNS reverse lookup " -
turning the numbers into a name.

Whereas forward lookups find the IP address of any given host name,
sometimes the reverse action is required, i.e. resolving IP addresses
into host names. Some servers will not pass data to systems where IP
addresses do not resolve to host names. This is to prevent a denial of
service attack by someone sending us many requests from bogus
addresses.  The reverse lookup zone files in the DNS provide the way in
which the IP-address to hostname resolution takes place.

I sense many web servers do not have reverse DNS lookups set up properly
or enabled. 

So far as I can tell the web sites and ftp site you tried are working
and are not down.

I will pass your request to our server manager Monday and see if we got
a reverse DNS lookup failure from you. He is out today.

Stu


> 
> Don't understand what you mean about "DNS reverse lookup". Could you explain 
> a little if it helps to solve this problem?
> 
> Thanks,
> 
> Joe
> 
> Stuart Wier <address@hidden> wrote:
> 
> >Joe,
> >
> >Please tell me how you are trying to download the IDV, ie which web page
> >and link you are using.
> >
> >Usually an inability to download Unidata software is due to a mismatch
> >between your forward and reverse DNS entries. This is a DNS issue on
> >your end.
> >
> >When your DNS permits reverse name lookup from Unidata you should be
> >able to download Unidata software.
> >
> >Stu Wier
> >
> >> >From: "Joe Floore" <address@hidden>
> >> >Subject: IDV - linux - Can't download IDV
> >> >Organization: UCAR/Unidata
> >> >Keywords: 200305301345.h4UDjfFm025721
> >>
> >> Institution:  /
> >> Package Version: 1beta6
> >> Operating System: linux
> >> Hardware Information: PC
> >> Inquiry: I am interested in the Integrated Data Viewer. I couldn't 
> >> download it however. Is the server down?
> >>
> >> Thanks,
> >>
> >> Joe
> >>
> >
> >--

-- 
****************************************************************************
Unidata User Support                                    UCAR Unidata
Program
303 497 8643                                                  P.O. Box
3000
address@hidden                                   Boulder, CO
80307
----------------------------------------------------------------------------
Unidata WWW Service             
http://my.unidata.ucar.edu/content/support
****************************************************************************