php-general Digest 31 Aug 2010 15:43:11 -0000 Issue 6919
Topics (messages 307758 through 307765):
Re: Questions about $_SERVER
307758 by: Paul M Foster
307759 by: Peter Lind
307761 by: Paul M Foster
307762 by: Peter Lind
307763 by: Paul M Foster
307764 by: Paul M Foster
Re: Secure Communication?
307760 by: Paul M Foster
a quick question about array keys
307765 by: Tontonq Tontonq
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----------------------------------------------------------------------
--- Begin Message ---
On Sun, Aug 29, 2010 at 06:04:23PM +0200, Per Jessen wrote:
> Jason Pruim wrote:
>
> > My understanding of how shared hosting works would make this near
> > impossible... Basically Apache grabs a header that is sent at the
> > initial connection which includes the destination hostname and from
> > there it translates it to the proper directory on the shared host.
> >
> > All the IP's though are based off of the parent site's server...
> >
> > Now with dedicated hosting where you have the entire machine you can
> > do what you are looking at because the IP address will always
> > translate back to your website.
>
> AFAICT, Tedd was not asking about the server, he's asking about the
> client.
No, he's talking about the server. But the server he's using may offload
the processing of a script to another machine. So
$_SERVER['SERVER_ADDR'] and $_SERVER['SERVER_NAME']
both relate to the server which the client is originally communicating
with. But he wants to know if he can get the same information about a
different remote server which is processing a script for him. The
problem is that we have:
$_SERVER['REMOTE_ADDR']
but no
$_SERVER['REMOTE_NAME']
So the question is, how would he get that last variable. It becomes
complicated when using a shared hosting environment, because server
names and IPs aren't a 1:1 mapping. An IP may represent numerous actual
site names. This was part or all of the reason why the http protocol was
revised from 1.0 to 1.1-- in order to accommodate all the domains, which
because of the cramped IP space of IPv4, had to share IPs. So in the
HTTP 1.1 protocol, there is additional information passed about the name
of the domain.
Paul
--
Paul M. Foster
--- End Message ---
--- Begin Message ---
On 30 August 2010 21:32, Paul M Foster <pa...@quillandmouse.com> wrote:
> On Sun, Aug 29, 2010 at 06:04:23PM +0200, Per Jessen wrote:
>
>> Jason Pruim wrote:
>>
>> > My understanding of how shared hosting works would make this near
>> > impossible... Basically Apache grabs a header that is sent at the
>> > initial connection which includes the destination hostname and from
>> > there it translates it to the proper directory on the shared host.
>> >
>> > All the IP's though are based off of the parent site's server...
>> >
>> > Now with dedicated hosting where you have the entire machine you can
>> > do what you are looking at because the IP address will always
>> > translate back to your website.
>>
>> AFAICT, Tedd was not asking about the server, he's asking about the
>> client.
>
> No, he's talking about the server. But the server he's using may offload
> the processing of a script to another machine. So
>
> $_SERVER['SERVER_ADDR'] and $_SERVER['SERVER_NAME']
>
> both relate to the server which the client is originally communicating
> with. But he wants to know if he can get the same information about a
> different remote server which is processing a script for him. The
> problem is that we have:
>
> $_SERVER['REMOTE_ADDR']
>
> but no
>
> $_SERVER['REMOTE_NAME']
>
> So the question is, how would he get that last variable. It becomes
> complicated when using a shared hosting environment, because server
> names and IPs aren't a 1:1 mapping. An IP may represent numerous actual
> site names. This was part or all of the reason why the http protocol was
> revised from 1.0 to 1.1-- in order to accommodate all the domains, which
> because of the cramped IP space of IPv4, had to share IPs. So in the
> HTTP 1.1 protocol, there is additional information passed about the name
> of the domain.
>
In the scenario painted, it's explicitly stated that one server acts
as a client in trying to access a resource on another server. Could
you enlighten me as to where the domain name of a client is located in
the request header fields? Here's the RFC for HTTP 1.1
http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.3
Regards
Peter
--
<hype>
WWW: http://plphp.dk / http://plind.dk
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</hype>
--- End Message ---
--- Begin Message ---
On Mon, Aug 30, 2010 at 09:53:46PM +0200, Peter Lind wrote:
> On 30 August 2010 21:32, Paul M Foster <pa...@quillandmouse.com> wrote:
> > On Sun, Aug 29, 2010 at 06:04:23PM +0200, Per Jessen wrote:
> >
> >> Jason Pruim wrote:
> >>
> >> > My understanding of how shared hosting works would make this near
> >> > impossible... Basically Apache grabs a header that is sent at the
> >> > initial connection which includes the destination hostname and from
> >> > there it translates it to the proper directory on the shared host.
> >> >
> >> > All the IP's though are based off of the parent site's server...
> >> >
> >> > Now with dedicated hosting where you have the entire machine you can
> >> > do what you are looking at because the IP address will always
> >> > translate back to your website.
> >>
> >> AFAICT, Tedd was not asking about the server, he's asking about the
> >> client.
> >
> > No, he's talking about the server. But the server he's using may offload
> > the processing of a script to another machine. So
> >
> > $_SERVER['SERVER_ADDR'] and $_SERVER['SERVER_NAME']
> >
> > both relate to the server which the client is originally communicating
> > with. But he wants to know if he can get the same information about a
> > different remote server which is processing a script for him. The
> > problem is that we have:
> >
> > $_SERVER['REMOTE_ADDR']
> >
> > but no
> >
> > $_SERVER['REMOTE_NAME']
> >
> > So the question is, how would he get that last variable. It becomes
> > complicated when using a shared hosting environment, because server
> > names and IPs aren't a 1:1 mapping. An IP may represent numerous actual
> > site names. This was part or all of the reason why the http protocol was
> > revised from 1.0 to 1.1-- in order to accommodate all the domains, which
> > because of the cramped IP space of IPv4, had to share IPs. So in the
> > HTTP 1.1 protocol, there is additional information passed about the name
> > of the domain.
> >
>
> In the scenario painted, it's explicitly stated that one server acts
> as a client in trying to access a resource on another server. Could
> you enlighten me as to where the domain name of a client is located in
> the request header fields? Here's the RFC for HTTP 1.1
> http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.3
>From http://www8.org/w8-papers/5c-protocols/key/key.html:
=== EXCERPT ===
Internet address conservation
Companies and organizations use URLs to advertise themselves and their
products and services. When a URL appears in a medium other than the Web
itself, people seem to prefer ``pure hostname'' URLs; i.e., URLs without
any path syntax following the hostname. These are often known as
``vanity URLs,'' but in spite of the implied disparagement, it's
unlikely that non-purist users will abandon this practice, which has led
to the continuing creation of huge numbers of hostnames.
IP addresses are widely perceived as a scarce resource (pending the
uncertain transition to IPv6 [DH95]). The Domain Name System (DNS)
allows multiple host names to be bound to the same IP address.
Unfortunately, because the original designers of HTTP did not anticipate
the ``success disaster'' they were enabling, HTTP/1.0 requests do not
pass the hostname part of the request URL. For example, if a user makes
a request for the resource at URL http://example1.org/home.html, the
browser sends a message with the Request-Line
GET /home.html HTTP/1.0
to the server at example1.org. This prevents the binding of another HTTP
server hostname, such as exampleB.org to the same IP address, because
the server receiving such a message cannot tell which server the message
is meant for. Thus, the proliferation of vanity URLs causes a
proliferation of IP address allocations.
The Internet Engineering Steering Group (IESG), which manages the IETF
process, insisted that HTTP/1.1 take steps to improve conservation of IP
addresses. Since HTTP/1.1 had to interoperate with HTTP/1.0, it could
not change the format of the Request-Line to include the server
hostname. Instead, HTTP/1.1 requires requests to include a Host header,
first proposed by John Franks [Fra94], that carries the hostname. This
converts the example above to:
GET /home.html HTTP/1.1
Host: example1.org
If the URL references a port other than the default (TCP port 80), this
is also given in the Host header.
Clearly, since HTTP/1.0 clients will not send Host headers, HTTP/1.1
servers cannot simply reject all messages without them. However, the
HTTP/1.1 specification requires that an HTTP/1.1 server must reject any
HTTP/1.1 message that does not contain a Host header.
The intent of the Host header mechanism, and in particular the
requirement that enforces its presence in HTTP/1.1 requests, is to speed
the transition away from assigning a new IP address for every vanity
URL. However, as long as a substantial fraction of the users on the
Internet use browsers that do not send Host, no Web site operator (such
as an electronic commerce business) that depends on these users will
give up a vanity-URL IP address. The transition, therefore, may take
many years. It may be obviated by an earlier transition to IPv6, or by
the use of market mechanisms to discourage the unnecessary consumption
of IPv4 addresses.
=======
My mistake, though: this change was by no means the only reason for the
creation of HTTP 1.1
Paul
--
Paul M. Foster
--- End Message ---
--- Begin Message ---
On 30 August 2010 22:34, Paul M Foster <pa...@quillandmouse.com> wrote:
> On Mon, Aug 30, 2010 at 09:53:46PM +0200, Peter Lind wrote:
>
>> On 30 August 2010 21:32, Paul M Foster <pa...@quillandmouse.com> wrote:
>> > On Sun, Aug 29, 2010 at 06:04:23PM +0200, Per Jessen wrote:
>> >
>> >> Jason Pruim wrote:
>> >>
>> >> > My understanding of how shared hosting works would make this near
>> >> > impossible... Basically Apache grabs a header that is sent at the
>> >> > initial connection which includes the destination hostname and from
>> >> > there it translates it to the proper directory on the shared host.
>> >> >
>> >> > All the IP's though are based off of the parent site's server...
>> >> >
>> >> > Now with dedicated hosting where you have the entire machine you can
>> >> > do what you are looking at because the IP address will always
>> >> > translate back to your website.
>> >>
>> >> AFAICT, Tedd was not asking about the server, he's asking about the
>> >> client.
>> >
>> > No, he's talking about the server. But the server he's using may offload
>> > the processing of a script to another machine. So
>> >
>> > $_SERVER['SERVER_ADDR'] and $_SERVER['SERVER_NAME']
>> >
>> > both relate to the server which the client is originally communicating
>> > with. But he wants to know if he can get the same information about a
>> > different remote server which is processing a script for him. The
>> > problem is that we have:
>> >
>> > $_SERVER['REMOTE_ADDR']
>> >
>> > but no
>> >
>> > $_SERVER['REMOTE_NAME']
>> >
>> > So the question is, how would he get that last variable. It becomes
>> > complicated when using a shared hosting environment, because server
>> > names and IPs aren't a 1:1 mapping. An IP may represent numerous actual
>> > site names. This was part or all of the reason why the http protocol was
>> > revised from 1.0 to 1.1-- in order to accommodate all the domains, which
>> > because of the cramped IP space of IPv4, had to share IPs. So in the
>> > HTTP 1.1 protocol, there is additional information passed about the name
>> > of the domain.
>> >
>>
>> In the scenario painted, it's explicitly stated that one server acts
>> as a client in trying to access a resource on another server. Could
>> you enlighten me as to where the domain name of a client is located in
>> the request header fields? Here's the RFC for HTTP 1.1
>> http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.3
>
> From http://www8.org/w8-papers/5c-protocols/key/key.html:
>
> === EXCERPT ===
>
> Internet address conservation
>
> Companies and organizations use URLs to advertise themselves and their
> products and services. When a URL appears in a medium other than the Web
> itself, people seem to prefer ``pure hostname'' URLs; i.e., URLs without
> any path syntax following the hostname. These are often known as
> ``vanity URLs,'' but in spite of the implied disparagement, it's
> unlikely that non-purist users will abandon this practice, which has led
> to the continuing creation of huge numbers of hostnames.
>
> IP addresses are widely perceived as a scarce resource (pending the
> uncertain transition to IPv6 [DH95]). The Domain Name System (DNS)
> allows multiple host names to be bound to the same IP address.
> Unfortunately, because the original designers of HTTP did not anticipate
> the ``success disaster'' they were enabling, HTTP/1.0 requests do not
> pass the hostname part of the request URL. For example, if a user makes
> a request for the resource at URL http://example1.org/home.html, the
> browser sends a message with the Request-Line
>
> GET /home.html HTTP/1.0
>
> to the server at example1.org. This prevents the binding of another HTTP
> server hostname, such as exampleB.org to the same IP address, because
> the server receiving such a message cannot tell which server the message
> is meant for. Thus, the proliferation of vanity URLs causes a
> proliferation of IP address allocations.
>
> The Internet Engineering Steering Group (IESG), which manages the IETF
> process, insisted that HTTP/1.1 take steps to improve conservation of IP
> addresses. Since HTTP/1.1 had to interoperate with HTTP/1.0, it could
> not change the format of the Request-Line to include the server
> hostname. Instead, HTTP/1.1 requires requests to include a Host header,
> first proposed by John Franks [Fra94], that carries the hostname. This
> converts the example above to:
>
> GET /home.html HTTP/1.1
> Host: example1.org
>
> If the URL references a port other than the default (TCP port 80), this
> is also given in the Host header.
>
> Clearly, since HTTP/1.0 clients will not send Host headers, HTTP/1.1
> servers cannot simply reject all messages without them. However, the
> HTTP/1.1 specification requires that an HTTP/1.1 server must reject any
> HTTP/1.1 message that does not contain a Host header.
>
> The intent of the Host header mechanism, and in particular the
> requirement that enforces its presence in HTTP/1.1 requests, is to speed
> the transition away from assigning a new IP address for every vanity
> URL. However, as long as a substantial fraction of the users on the
> Internet use browsers that do not send Host, no Web site operator (such
> as an electronic commerce business) that depends on these users will
> give up a vanity-URL IP address. The transition, therefore, may take
> many years. It may be obviated by an earlier transition to IPv6, or by
> the use of market mechanisms to discourage the unnecessary consumption
> of IPv4 addresses.
>
> =======
>
> My mistake, though: this change was by no means the only reason for the
> creation of HTTP 1.1
Not only that, it has nothing whatsoever to do with the case at hand.
The Host header field specifies the domain you're asking a resource
from, not the the domain of the client. Hence, it cannot be used in
any fashion to provide identification of the client doing the request,
which is what Tedd wanted.
Regards
Peter
--
<hype>
WWW: http://plphp.dk / http://plind.dk
LinkedIn: http://www.linkedin.com/in/plind
BeWelcome/Couchsurfing: Fake51
Twitter: http://twitter.com/kafe15
</hype>
--- End Message ---
--- Begin Message ---
On Mon, Aug 30, 2010 at 10:34:42PM +0200, Peter Lind wrote:
> On 30 August 2010 22:34, Paul M Foster <pa...@quillandmouse.com> wrote:
> > On Mon, Aug 30, 2010 at 09:53:46PM +0200, Peter Lind wrote:
> >
<snip>
> >> > $_SERVER['REMOTE_NAME']
> >> >
> >> > So the question is, how would he get that last variable. It becomes
> >> > complicated when using a shared hosting environment, because server
> >> > names and IPs aren't a 1:1 mapping. An IP may represent numerous actual
> >> > site names. This was part or all of the reason why the http protocol was
> >> > revised from 1.0 to 1.1-- in order to accommodate all the domains, which
> >> > because of the cramped IP space of IPv4, had to share IPs. So in the
> >> > HTTP 1.1 protocol, there is additional information passed about the name
> >> > of the domain.
> >> >
> >>
> >> In the scenario painted, it's explicitly stated that one server acts
> >> as a client in trying to access a resource on another server. Could
> >> you enlighten me as to where the domain name of a client is located in
> >> the request header fields? Here's the RFC for HTTP 1.1
> >> http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.3
> >
> > From http://www8.org/w8-papers/5c-protocols/key/key.html:
<snip>
> >
> > My mistake, though: this change was by no means the only reason for the
> > creation of HTTP 1.1
>
> Not only that, it has nothing whatsoever to do with the case at hand.
> The Host header field specifies the domain you're asking a resource
> from, not the the domain of the client. Hence, it cannot be used in
> any fashion to provide identification of the client doing the request,
> which is what Tedd wanted.
Tedd was looking for the server name for the remote server, as seen from
the perspective of the asking server. In his example, he was looking for
a variable which would tell him "Slave's" name from "Master's"
perspective. That's why he was asking if there was anything like
$_SERVER['REMOTE_NAME'] as a known PHP server variable.
Of course, you're correct in that the HTTP 1.1 spec I cited wouldn't help
him. I just mentioned it as being of tangential interest.
Paul
--
Paul M. Foster
--- End Message ---
--- Begin Message ---
On Mon, Aug 30, 2010 at 05:13:59PM -0400, Paul M Foster wrote:
> On Mon, Aug 30, 2010 at 10:34:42PM +0200, Peter Lind wrote:
>
> > On 30 August 2010 22:34, Paul M Foster <pa...@quillandmouse.com> wrote:
> > > On Mon, Aug 30, 2010 at 09:53:46PM +0200, Peter Lind wrote:
> > >
>
> <snip>
>
> > >> > $_SERVER['REMOTE_NAME']
> > >> >
> > >> > So the question is, how would he get that last variable. It becomes
> > >> > complicated when using a shared hosting environment, because server
> > >> > names and IPs aren't a 1:1 mapping. An IP may represent numerous
> actual
> > >> > site names. This was part or all of the reason why the http
> protocol was
> > >> > revised from 1.0 to 1.1-- in order to accommodate all the domains,
> which
> > >> > because of the cramped IP space of IPv4, had to share IPs. So in the
> > >> > HTTP 1.1 protocol, there is additional information passed about
> the name
> > >> > of the domain.
> > >> >
> > >>
> > >> In the scenario painted, it's explicitly stated that one server acts
> > >> as a client in trying to access a resource on another server. Could
> > >> you enlighten me as to where the domain name of a client is located in
> > >> the request header fields? Here's the RFC for HTTP 1.1
> > >> http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.3
> > >
> > > From http://www8.org/w8-papers/5c-protocols/key/key.html:
>
> <snip>
>
> > >
> > > My mistake, though: this change was by no means the only reason for the
> > > creation of HTTP 1.1
> >
> > Not only that, it has nothing whatsoever to do with the case at hand.
> > The Host header field specifies the domain you're asking a resource
> > from, not the the domain of the client. Hence, it cannot be used in
> > any fashion to provide identification of the client doing the request,
> > which is what Tedd wanted.
>
> Tedd was looking for the server name for the remote server, as seen from
> the perspective of the asking server. In his example, he was looking for
> a variable which would tell him "Slave's" name from "Master's"
> perspective. That's why he was asking if there was anything like
> $_SERVER['REMOTE_NAME'] as a known PHP server variable.
I'm mistaken here. He's looking for the name of the server making the
request, which doesn't appear to be transmitted anywhere.
Paul
--
Paul M. Foster
--- End Message ---
--- Begin Message ---
On Sun, Aug 29, 2010 at 12:24:31PM -0400, tedd wrote:
> Hi gangl:
>
> I realize that the problem stated herein has been solved by others,
> so I'm not claiming I've done anything new -- it's only new to me. It
> was a learning experience for *me* and my solution may help others.
>
> In any event, I've finished creating a method for establishing what I
> think is secure communication between two servers. I've written two
> scripts that run on different servers, which confirm communication
> between them via hard-wired urls and creating/writing/reading a
> url-confirmation file.
>
> The purpose of this exercise was to simply to keep database-access
> data (i.e., user_name, password, key to decryption) secret. However,
> the secret could be anything you want to keep secret -- secret being
> defined as no data residing on the server of concern while allowing
> that server access to the data when needed and under authorization.
>
> Here's what I've done -- I have two domains, namely webbytedd.com
> (the Master) and php1.net (the Slave) -- both domains reside on
> different servers. The domain names really don't matter, it's just
> that this method currently works between those two domains.
>
> Statement of Requirements:
>
> 1. The Master requires "access" to it's database.
>
> 2. The Slave keeps "access" to Master's database in it's own database.
>
> 3. It's required that "access" remain secret in the event that the
> Master is hacked.
>
> *The term "access" above is defined as database-access data, such as
> user_name, password, and key to decryption.
>
> Description of Method:
>
> 1. When the Master wants access to it's database, it first creates a
> url-confirmation file and writes a token to that file, which resides
> on the Master. I've used time() as the token, but the token could be
> any variable -- it really doesn't make much difference other than the
> value should be different each time.
>
> 2. The Master then sends a cURL request to the Slave via a POST where
> the POST variable contains the token.
>
> 3. The Slave when receiving the POST request from Master reads the
> token from the newly created url-confirmation file residing on the
> Master and then compares that token with the token provided by the
> POST -- if the tokens match, then the Slave returns "the access" to
> the Master. If not, the process fails.
>
> 4. After receiving "access" the Master deletes the url-confirmation
> file and continues with it operation. If the Master does not receive
> "access" then it deletes the url-confirmation file and exits.
>
> This method sounds simple enough and does several things.
>
> 1. There is no "access" stored on the Master.
>
> 2. While the Slave has "access" for the Master stored in its
> database, the access to the Slave's database is kept in an
> out-of-root (not open to the web) file. Note, in this case, this was
> not possible on the Master because the host did not allow out-of-root
> files -- but that is only tangential to the problem addressed here.
>
> 3. If a hacker did obtain access to the Slave database, then the
> hacker would discover the contents have been encrypted and only the
> Master has the decryption key kept in it's database.
>
> 4. If a hacker did obtain access to the code residing on the Master,
> then the hacker could not access the Master's database because the
> "access" data is recorded on another server (i.e., Slave).
> Furthermore, the hacker could not get the code to run anywhere else
> because the Slave's "look-up URL" for the url-confirmation file is
> hardwired to the Master address.
>
> 5. And lastly, all communication between both domains is done via https.
>
> Now, for the exception of both server's being hacked at the same
> time, what could go wrong?
>
> Cheers,
>
> tedd
A couple of things I'm unsure about. Here's what I *think* is going on:
The actual database with the Master's data is located on the Master
machine.
The "keys" to this data are contained on the Slave server, in *its*
database.
The Slave's database is encrypted, so that the "keys" to the Master
database can't be derived even if a hacker hacks the "Slave" machine.
The "keys" to the Slave database are held by the Master.
So when the Master asks the Slave for access, it must send across the
keys for the Slave to access its own database. The Slave then decodes
its database and sends the Master back the "keys" for the Master's
database. The Master can then make queries to its database unfettered.
Is that about right?
Other than the fact that this solution should be rife with latency
issues, it seems like it would be secure.
I assume you're doing this as an academic exercise. If you had an actual
client who wanted to go to this much trouble to secure their data, I
think I would opt for the previously suggested solution of getting a
dedicated server or two.
Paul
--
Paul M. Foster
--- End Message ---
--- Begin Message ---
a quick question
lets say i have an array like that
Array
(
[300] => 300
[301] => 301
[302] => 302
[303] => 303
[304] => 304
[305] => 305
[306] => 306
[307] => 307
[308] => 308
...
how can i change keys to 0,1,2,3,.. by faster way
(it should like that) >
Array
(
[0] => 300
[1] => 301
[2] => 302
[3] => 303
....
--- End Message ---
