Firewall problem with same IP address

See if you can use the network Card MAC address instead of the IP address.
This may help ?

I think the problem is the firewall is blocking the udp port. The firewall will not assign ip addresses, or translate them. the clients will still have individual ip addresses. ICS does NAT, as does of course NAT (in w2k) and a linksys router does dhcp and nat, but a firewall just blocks ports. Open up the udp ports (choose a specific one) and write your app to use that one, and the app should work

> See if you can use the network Card MAC address instead of the IP address.

It would be a very-poor firewall if it "exposed" the MAC addresses -- all you should see is the MAC-address of the firewall.

Otta : In theory yes, but If he is writing his own client  software, he should be able to get the MAC address of the machine it is running on.

>See if you can use the network Card MAC address instead of the IP address

Maybe yes, but i don't know how to obtain MAC under Windoze
or Linux, the standart socket API has no function for it.

Maybe I am misunderstanding, but are you talking about two clients on the same network with the same IP address? That would be a bad situation all around.

I will assume then that you are talking about two different networks, each with its own firewall, but each using the same reserved IP addresses for the "safe" area internally. Wouldn't you have to interface with the outward facing NIC on the firewall and have the firewall configured to forward the port request on to the appropriate client?  The firewalls should not share the same ip address for the external interface.

> but are you talking about two clients on the same network with the same IP address?

I think that he's talking about two clients,
behind some NAT ("Network Address Translation") firewall/router.

Each request to the Internet-connected server
comes from the _same_ IP-address, namely the IP-address
of the firewall/router, but on, of course, different TCP (or UDP) ports.

if you can run a batch file or *.exe during setup,
do an ipconfig /all > ttt.txt  or do a find | redirect on it.

parse ttt.txt  or redirect for the Physical Address which is the MAC address.
try this on you own machine for example and you will get the idea.

I hope this helps !

considering the client software would have the ability to obtain the mac address, wouldn't it also have the ability to obtain the hosts private address as well...just another alternative to parsing for the mac address.

don't know what language or network level you are programming with...but you could also implement an incremental id, unique, or session id in your application udp headers to distinguish between same-sourced clients.

I'm talking about two clients on same network (they have different IP in LAN for example 192.168.1.20 and 192.168.1.21) but they have same IP behind firewall. Firewall do masquerading so every client on the LAN have same IP in Internet. I need differ client with same IP if they are two different machines behind firewall. All client comunicate on same UDP port. (for example: client1 ->192.168.1.20:27000; client2 ->192.168.1.21:27000)

sorry for late asignment experts points. :(( i was very busy and i forgot look at it. your answer help a lot. thanks