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[NSE] Detecting IP forwarding
From: Patrik Karlsson <patrik () cqure net>
Date: Sun, 22 Apr 2012 20:55:10 +0200

Hi all,

I had a discussion about ip forwarding and "internet connection sharing"
with a friend the other day.
The discussion was about detecting multi homed laptops having both the
wireless and wired network interfaces active and ip forwarding enabled.
I came up with the attached script which essentially tries to use each
scanned host as a gateway and sends a ping packet to a given target (either
on the same LAN or routed).
It then sees whether it gets a ICMP echo reply or redirect back and
determines whether the packet was forwarded or not.

I've tried it against Windows 7 connection sharing, my home router and a OS
X server with ip forwarding activated and it works as intended.
If there's another more efficient way to discover this, let me know,
otherwise I will commit the script within the next few days.

The script relies on some recent changes to packet.lua, so it needs this to
be updated library as well.

Patrik Karlsson

Attachment: ip-forwarding.nse

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