Monitor Router Cisco Activity

[pacifico.lombardi]

I have a private lan that is connected to the public network with a Pc that have proxy server installed and that have two network cards. All Pc in the network access the server and the second network card allow to go out to public network with proxy server configuration using a router cisco.

For example my private network have Ip address 192.168.4.XX and i've buy public addresses from 217.25.12.xx to 217.25.12.xx. The server have the first network card with address 192.168.4.1 and the second with 217.25.12.12 and the default gateway is the address of the router 217.25.12.11. Is possible to monitor what IP address access the router reading lan packet that receive the router or the address in lan packet is always the address of the second nework card of the server? If it's possible reading lan packet i coul'd i do it in visual C or Visual Basic?

thanks

Mat

[murabi]

From your question, I think the proxy server is doing the address translation. Right? In that case, the IP packets hitting the Router will have the translated IP address coming from the proxy server.

If you want to see the packets hitting the router, you can use any network sniffers, like Network General. There are also some software based network sniffers.

You can also read the packets hitting the router using "debug ip packets" command, but they are very very CPU intensive and may slow down or totally shutdown the router, if the number of packets are high. So be very very careful when using debug commands on a production router. You can use this command in a lab, if you want.

I am not sure if we can do this with Visual C or Visual Basic.