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I'm learning about Smurf Attacks. Since they need to use a broadcast address, doesn't that mean they can't work over the internet? For example if an attacker sends a router the packet with the destination the broadcast attack that works, but routers don't normally broadcast passed the network edge.

But then how does a Smurf Amplifier work if they don't have to be on the same network? I'm confused.

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Smurf attacks were popular in 19th , however there a few devices that are still vulnerable to this attack. Smurf attacks are not only possible in a LAN, but work over WAN too. It depend upon the configuration of your routing devices.All the websites, VPS, and public gateways do have a public IP. So, if you can generate large numbers of ICMP packets with the intended victim's spoofed source IP and then broadcast to a computer network using an IP Broadcast address, then they will be flooded.

This means if a router with a public IP allows to respond to ICMP or allow to forward packet to broadcast IP, then it can lead to a DoS over all other host who are assigned the router as the gateway.

Protections against it are:

  • Configure individual hosts and routers to not respond to ICMP requests or broadcasts; or
  • Configure routers to not forward packets directed to broadcast addresses

Until 1999, standards required routers to forward such packets by default. Since then, the default standard was changed to not forward such packets.

You can find current top ten smurf amplifiers facing this attack

http://smurf.powertech.no

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    Smurf attacks were popular when? – schroeder Dec 13 '15 at 5:39
  • Ok so I have trouble understanding the way you wrote it but I think I know what's going on. Is it before 1999 the standard was for routers to allow incoming broadcast requests from the internet, but after 1999 the standard was for this feature to be disabled by default? – Celeritas Dec 13 '15 at 10:00

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