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Syn-Cookies
From NetSec
Revision as of 16:07, 28 September 2012 by Gonzalo58T (Talk | contribs) (Was complete bullshit. Fixing it with proper info.)
Syn-cookies is a counter-measure against SYN flood attacks (see: three-way tcp handshake) that enables resilience against these by storing the necessary state informations of the 3-way-handshake into some TCP headers (the Options and Timestamp headers) instead of keeping it in the server's RAM. Since it is a hack over TCP, Syn-cookies are usually automatically enabled during SYN-flood attacks by the operating system's network stack.
To disable them on Linux, set net.ipv4.tcp_syncookies to 0 (or write 0 into /proc/sys/net/ipv4/tcp_syncookies)
Syn-Cookies protect servers from basic SYN flood attacks quite well.
