Hi all, sorry to bother on this but my google searches haven't been
useful (probably because I'm not an expert on this).

I wonder whether I Apache + mod_proxy would be ok to handle this
situations:

- some of my users have a legacy application we cannot change that used
to connect to xyz.olddomain.com to download some data.

- xyz.olddomain.com doesn't exists anymore but we know the protocal
used to exchange data

I would like my user to set zork.mydomain.com as a http proxy in their
legacy application and have my proxy redirect all the requests done by
the legacy app towards xyz.olddomain.com to that same mydomain.com
server

My understanding is that I need to use the reverse proxy functionality
but I also need the forward one to let the user set my proxy in their
application.

If the explanation is too long and you have links that can I would
be already happy with them!

Thanks a lot in advance
Zork

On 2006-10-03, Zork <skills102@googlemail.com> wrote:
> - some of my users have a legacy application we cannot change that used
> to connect to xyz.olddomain.com to download some data.

Connect using the domain name or directly with the IP?

Anyway, I'd use an IP DNAT to fool the application and have all the
request to 'xyz.olddomain.com' redirected to a different IP. This is
completely invisible to the application and works regardless of the
protocol used.

Davide

--
Caller: I just installed Windows 95 on my computer.
Tech Support: And...?
Caller: It's not working.
Tech Support: You already said that.

Thanks Davide,

> Connect using the domain name or directly with the IP?

domain name

Anyway the users are spread around and not on the same intranet (they
travel and use their laptop + an internet connection from hotels and so
forth).

That's why I was thinking about a proxy server (which is the only thing
which is configurable in that crappy legacy app).

Knowing this would apache + mod_proxy be enough? I really need a simple
solution, nothing complicated

Zork

On 2006-10-03, Zork <skills102@googlemail.com> wrote:
>> Connect using the domain name or directly with the IP?
> domain name

Then you could just fool the apps by having 'xyz.domain.com' in the
/etc/hosts file (pointing it to wathever you want).

> That's why I was thinking about a proxy server (which is the only thing
> which is configurable in that crappy legacy app).

Yes, if you use DNAT it doesn't matter what kind of apps it is, the
redirection is done at IP level.

> Knowing this would apache + mod_proxy be enough? I really need a simple
> solution, nothing complicated

Well, I tend to think that using a proxy just to do an ip redirection is
the complicated solution. I mean, a simple

iptables -t nat -A PREROUTING -d ip.of.the.server -j DNAT \
--to ip.of.the.newserver

should do it, but if you want to go for the full proxy, go ahead.

Davide


--
!07/11 PDP a ni deppart m'I !pleH

Thanks again

> Then you could just fool the apps by having 'xyz.domain.com' in the
> /etc/hosts file (pointing it to wathever you want).

they cannot change that file (they basically cannot do anything on
those laptop other than running the legacy app, check email a browse
the web). Ah, these are Windows XP machines

> Yes, if you use DNAT it doesn't matter what kind of apps it is, the
> redirection is done at IP level.

I'm not quite sure how this would work. Example:

- they connect to the internet using the wifi of an hotel
- start the legacy app and the app tries to connect to
xyz.olddomain.com which doesn't exist anymore.

How can a DNAT on my server ?

> > Knowing this would apache + mod_proxy be enough? I really need a simple
> > solution, nothing complicated
>
> Well, I tend to think that using a proxy just to do an ip redirection is

it's not an IP redirection: the legacy app need to think it is
communicating with the non existent server xyz.olddomain.com and the
only way, seems to me, it to have it connect thgrough a proxy which
will do the trick and serve the content they need from the very same
server. :-)

Zork

On 2006-10-03, Zork <skills102@googlemail.com> wrote:
> they cannot change that file (they basically cannot do anything on
> those laptop other than running the legacy app

ah, ok, then the problem is that the application is a *client* (and it
doesn't reside in the server like I understood). then the problem is:
will the application follow the rule you set for the proxy or will he
still connect to his own server (if is hardwired, is hardwired)?

If he follow the rule of the proxy then you could fool it by using the
proxy solution, otherwise I don't see a big chance of doing it.

But you'll know only after you test it.

Davide

--
!07/11 PDP a ni deppart m'I !pleH

> ah, ok, then the problem is that the application is a *client* (and it
> doesn't reside in the server like I understood).

yes, sorry it wasn't clear in my first post

> then the problem is will the application follow the rule you set for the proxy or will he
> still connect to his own server (if is hardwired, is hardwired)?

they can set a proxy server in the app configuration, I tried with a
simple debug proxy and I correctly see their connections.

> If he follow the rule of the proxy then you could fool it by using the
> proxy solution, otherwise I don't see a big chance of doing it.

yep and this is what I don't know how to do. I'm trying to set up a
proof of concept to show them we have a temporary solution until we
rewrite the whole application :-)

Looking at the (poor) docs I found online I need to use the forwarding
mod_proxy feature to let the user set proxy.mydomain.com in their
application but then need something like the reverse mod_proxy feature
to transalte transparently the legacy app request to xyz.olddomain.com
to fake.mydomiain.com.

Any hints? Thanks a lot!

On 2006-10-03, Zork <skills102@googlemail.com> wrote:
> yep and this is what I don't know how to do.

Since the apps will use the server as a proxy, I suspect that you'll
still receive the request pointing to the destination server, then
you should be able to do something like

NameVirtualHost *

<VirtualHost *>
Servername xyz.domain.com
ProxyPass / http://whereveryouwant/
ProxyPassReverse / http://whereveryouwant/
</VirtualHost>

But without being able to see the application first-hand, is difficult
to say. You could also try with a real proxy server (Squid).

Davide

--
!07/11 PDP a ni deppart m'I !pleH