tcp_syncookies. Send out syncookies when the syn backlog queue of a socket overflows. This is to prevent against the common “syn flood attack”. Disabled (0) by default. :–:cat /proc/sys/net/ipv4/tcp_syncookies 0 :–: added from linux kernel source. /* 160 * Generate a syncookie. mssp points to the mss, which is returned 161 * rounded down to …