Help setting up a 1751 Router / PIX 506E

[EduardoA]

I need a little help setting up my company's network. I have a Cisco 1751 Router and a PIX 506E Firewall. I only have one Internet IP Address, which I want my internal network to use when going on the Internet. I know I will have to setup the PIX with PAT so my internal users can get out on the Internet. My question is, what should my IP addresses be for the rest of the network, LAN is using 192.168.0.X, I am not sure what IP addresses I should give to PIX’s External/Internal interface and the Router’s NIC connected to PIX’s external interface???????????


Router 1751 ---- PIX 506E ----- Switch -------
|
|
LAN


Router's IP:
NIC connected to service provider 206.172.X.X

NIC connected to PIX’s external NIC xxx.xxx.xxx.xxx ?


PIX’s IP: External xxx.xxx.xxx.xxx ???
Internal xxx.xxx.xxx.xxx ???

I am new to this, so any help would be greatly appreciated.

Thanks in advance,

Eduardo

 

[rburke]

What I would do is set the external interface to another subnet to the class C 192.168.x.x network. So, on the router interface connected to the PIX I would put in 192.168.10.1 255.255.255.0 and on the PIX I would put hte external interface to 192.168.10.2 255.255.255.0. Then the internal interface for the PIX will be your gateway for your LAN. So the internal interface will be 192.168.0.1 255.255.255.0 and then you can assign IP's via DHCP, or statically for your LAN. Hope this helps..... Let me know....

Burke

 

[EduardoA]

Burke,

Thanks a lot for the help, now I get a better understanding for my company's network setup. I was confuse, cause while reading my PIX book it said that the PIX's external interface would have to have an Internet IP Address in order to use PAT.

Now, let me ask you one more question. What command should I use when configuring PAT, so my users use the Router's external IP address to go on the internet? After this I should be pretty much set and ready to go.

Thanks again for your help.

Eduardo

 

[Guest_imported]

Let's assume your ISP gave you the IP address 206.172.10.1

That will be the IP address of the Wan side of your PIX
firewall. The LAN side of your PIX will be set to say
192.168.0.1

The computers behind the PIX (inside your LAN) will use
192.168.0.xxx for their IP addresses, then you set the
default gateway on each computer to point to 192.168.0.1

This way, your computers inside the LAN will automatically
send all non 192.168.0.xxx packets to the default gateway
(your PIX firewall) and out the 206.172.10.1 interface to
the rest of the world.

paul

 

[Guest_imported]

given the above config;
ip address outside 206.172.10.1 {mask}
global (outside) 1 interface
nat (inside) 1 192.168.0.0 255.255.255.0