Change server ip address

Hello experts,

In our net work we have a full class c ips and some custom applications been written in a way as pointed to the ip address already. Recently we are going to move those application servers inside of firewall as well as most of the end users. Now the problem is how to make those custom build application pointed at real ip address to function. It will be a very time consume job to go through all the codes and change them.
Is it possible to make the individule application machine when pointing to 45.5.22.X then means go to 192.168.10.x ? Thanks for help.


Mark
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tomcattyyAsked:
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Steve KnightConnect With a Mentor IT ConsultancyCommented:
Hmm, so you have

45.5.22.x
    |
Router / Firewall
    |
192.168.10.x

Are the users of your application on the inside or outside?  In any case what you can do setup NAT forwarding rules in the firewall so that access to 45.5.22.x on port xxxx goes to 192.168.10.x on port xxxx for instance.

Anyone on the 192.168.10.x address would still try and connect to 45.5.22.x so would need to be able to communicate with it.  This can be done in some firewalls, effectively you are looping back into your own network, sometimes called triangulation etc. e.g. from 192.168.10.100 (client pc) to 45.5.22.x gets to firewall, firewall has NAT rule that says 45.5.22.x goes to 192.168.10.5 and traffic goes back out onto the LAN interface.

One other method which ecszone suggests to a certain extent would be to have a second IP address (possibly may have to be a second NIC in this instance) on the application box with the external IP on it.  So it has 192.168.10.5 and 45.5.22.5 for instance.  You could then add a static route to each machine, or to your normal default gateway router as route -p 45.5.22.5 mask 255.255.255.255 192.168.10.5.  Any packets for the specific host 45.5.22.5 would then go to 192.168.10.5 and be routed to it's other interface and hopefully to the application listening port.  As it is behind NAT firewall the server when talking to the outside world would be able to talk to all external addresses still.

It is a pity you can't amend the apps in some way, the app writers were certainly not very thoughtful, a hostname or DNS name would make much more sense!

Steve
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jcdesign4uCommented:
Mostly those applications have configuration files (like a *.ini) where you can configure those ip adresses.
I don't think you can do it on another way. If the applicitions where pointing at the computername then it would be an easier job.
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EricIT ManagerCommented:
YOu may be able to make a static route?  use  from cmd
route print
route /?
i never done this but maybe make a route from 45.5.22.x go to 192.168.10.x,
not sure if it will work, but only do a dingle IP not subnet or it will interfear with other traffic
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tomcattyyAuthor Commented:
Thanks for the fast response, I will try to impliment in this week and update the status.
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tomcattyyAuthor Commented:
Hello experts, on the firewall we create a loopback NAT rule and resolve this problem, thanks for the answers
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Steve KnightIT ConsultancyCommented:
No problem, thanks for the points.

Steve
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