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I'm trying to setup a router using iptables.

But, after a lot of examples I've tried, I can't get anything to work.

My idea is to setup a box in between my Cisco and the main switch for firewall, bandwidth graphs, filtering, etc.

I am using an old laptop as a test unit for now.

  • Interface eth0 is static with an ip of and gw This works as a valid Internet connection.

  • Interface eth1 is static with an ip of

I have forwarding enabled via sysctl.conf and double checked the value inside ip_forward.

When I connect a test Windows laptop via cable to eth1, I get no DHCP (dhcp is handled by the Cisco on This is normal I suspect since I need several iptable rules, but the question is which? I have tried so many variations but none seem to work, can anyone help me please?


eth0 :
eth1 :

CISCO<->[eth0]box[eth1]<->devices(eg. Windows laptop)

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