Stealth IP Stack is a kernel patch for Linux 2.2.17 which makes your machine almost invisable on the network without impeding normal network operation. Many denial of service attacks, such as stream, are much less effective with this patch installed, and port scanners slow to a crawl. It works by restricting TCP RST packets (no "Connection Refused"), restricting ICMP_UNREACH on udp (Prevents UDP portscans), restricting all ICMP and IGMP requests. A sysctl interface is used so these features can be turned on ande off on the fly.
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