Simulating the Internet

[JimPletcher]

I have a short-term need to simulate multiple simultaneous connections to the Internet (to configure and test several consumer-grade vpn routers before deploying them).

Does anyone have any ideas how to do this on an isolated network? Nothing I've tried so far seems to work.

Before someone says *nix, a Linux server is available, but I very limited experience with it.

Thanks!

 

[ChrisAC]

Why simulate an internet connection? Why not just connect them to the 'real' internet?

Chris.


**********************
Chris Andrew, CCNA, CCSA
chris@iproute.co.uk
**********************

 

[JimPletcher]

Thanks for the response.

Because I don't have that many (13) simultaneous connections (static IP addresses).

 

[Serbtastic]

Why not use NAT? Or do you have a requirement for public (routable) IP addresses?

 

[JimPletcher]

Need routeable addresses.

However, it doesn't look like I'm going to find an alternative to setting up & testing the vpn firewalls one-at-a-time, on each of the sites.

I was hoping to aviod the travel time.

 

[krr]

I do this with an old Cisco router (2503) I have hanging around. The Ethernet interface of the router is connected to a hub and this hub is my "test-internet". I just have to configure the "official" IP addresses I need for testing as secondary addresses on the router's Ethernet interface.

You coud do this with your Linux box as well. Activate routing and define sub-interfaces for eth0 with the test IP addresses. Should pretty much work the same way.

BTW, this is called "router-on-a-stick", because it is routing several IP networks over a single interface.

This setup will only simulate Ethernet connections. If you are going to test boxes with e.g. integrated DSL modem, it won't work.

Cheers *Rob

 

[JimPletcher]

Thanks Rob,

Your's is the first intelligent response I've received (and I asked the same question on several forums).

Since I don't have access to anything like an old Cisco router, - I'm going to give Linux a try. It seems to be my only option.

Thanks again!

 

[krr]

Glad I can help. Here is a "starter" for your Linux box:

Check if routing is enabled:

cat /proc/sys/net/ipv4/ip_forward

0 = disabled
1 = enabled

Enable routing:

echo 1 > /proc/sys/net/ipv4/ip_forward

List all active interfaces:

ifconfig

Create new subinterfaces and give them IP addresses:

ifconfig eth0:0 10.10.128.1 netmask 255.255.255.0
ifconfig eth0:1 10.10.129.1 netmask 255.255.255.0

You can put the commands in a shell script so that you don't have to enter them after each reboot (but who needs to reboot a Linux machine, anyway? .

Cheers *Rob