Re: IP Spoofing/Masquarading

[Samuel Korpi <korpi.samuel () gmail com>]

2009/9/9 M.D.Mufambisi <mufambisi () gmail com>:
> I understand that IP packets can be spoofed ie change the source
> address to make it look like they originated from the internal LAN.
> However, when this is done across the internet, with a private IP
> address in its source field, how does this packet get routed through
> the internet?
The main issue is, how do the reply packets get back to the attacker?
If the source address is spoofed, the destination address for the
reply packets is invalid and the attacker has no idea whether the
original packet successfully reached its destination.

To answer your original guestion, the packet with spoofed source
address may or may not get routed through the Internet. Packets with
the so called private IP addresses (e.g., 10.x.x.x address space) are,
in general, dropped by Internet routers. Also, the outbound firewall
might check for spoofed addresses and drop those packets.

/Samuel

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