I need to setup my IPTABLES firewall to use allow DHCP address in but of course I don't know what the server is untill I get an address. I am hoping that I can open it for a moment to find it and then close it.

The issue is that I don't know how to find out what server it used.
Can I use IFCONFIG? or is there another utility?

You shouldn't need to configure iptables to handle dhcp, linux will punch the dhcp server through the firewall for you when you boot.

Usually you should be able to find the dhcp servers address either through your isp or network administrator. Just call them up and ask. If you have a broadband connection you should be able to find it using a network configuration tool (in redhat 8 use redhat-config-network)

Beyond that, it's hard to guess at which tool to use, as you didn't list your linux distrobution.

I run Redhat 8. And I wasn't able to get an ip but I will try again. Thanx.

Try running the network tool (start button->system settings->network). You should see an entry for your ethernet card (eth0). Click on edit and there should be an option that says "automatically obtain ip address with". First click the radio button in front of the line and then click the drop-down menu and select dhcp. Once your done, click ok and go back to the first menu and make sure that the interface is activated.Most of the time this should work depending on your setup. If you have a cable or dsl line with a broadband router, it should be able to grab it's address from the router. You have to be root to do this or it will prompt you for roots password.