At the minute I have all my machines connect directly to my isp-supplied broadband router. I want to make sure my machines are behaving correctly so I wish to test this by sniffing the traffic of each. How do I set up a linux box I have that has 2 network adapters, one ethernet one wireless, to act as (invisible) proxy to the network for another box connected to it via the ethernet port?

So in effect I want my proxy box to look after the DNS, HTTP and whatever ethernet multicast requests are normally serviced by the router. I have wireshark setup on my proxy box to sniff the traffic that comes through it's ethernet adapter, so I just need to know what I need to do to set it up as a fully-functioning proxy. The would-be proxy is Debian based.


Install bridge-utils, remove ip-addresses from eth0+eth1 and add bridge to /etc/network/interfaces:

iface br0 inet dhcp
    bridge_ports eth0 eth1

More info in http://wiki.debian.org/BridgeNetworkConnections

  • if one is a wlan0 adapter does that make a difference? (ie can I bridge_ports wlan0 eth0?) – user34789 Apr 15 '13 at 22:11
  • Some wlan adapters might be really picky about bridging so it's just best to try (or buy separate wireless AP) – Anssi Kolehmainen Apr 18 '13 at 19:25

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